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Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols
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NUCLEAR SCIENCE AND TECHNIQUES
Nuclear Science and Techniques, Vol.18, No 1 (2007) 2-9
Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols Mingzhang LIN Mehran MOSTAFAVI Yusa MUROYA Isabelle LAMPRE * Yosuke KATSUMURA l V 3 , * ('Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, Hongo 7-3-1,Bunkyo-ku, Tokyo 113-8656, Japan; 'Laboratoire de Chimie Physique/ELYSE, UMR 8000 CNRS / Universite' Paris-Sud, Centre d'Orsay, BBt. 349, 91405 Orsay Cedex, France; 'Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata Shirane, Tokaimura. Nakagun, Ibaraki 31 9-1188, Japan)
Abstract The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-'.m* for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolfic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.
Key words Polyols, Solvated electrons, Picosecond pulse radiolysis
CLC number 0 6 2 1.25
1
Introduction
The chemical effects of ionizing radiation on liquids have been extensively studied for decades in steady state and pulse regimes. Among the radicals produced by irradiation, the solvated electron (e,-) has been the subject of a huge amount of publications. Since the first measurements in water, the optical absorption of the solvated electron has been observed in more than a hundred solvents. Due to this property, the reactivity of the solvated electron has been studied by transient absorption measurements in many solvents, such as water or alcohols, using pulse radiolysis techniques [lF8'. The properties of the solvated electron depend on * Corresponding author, Email:[email protected],ac.jp
several factors, such as the solvent, the temperature, and the pressure. For instance, at room temperature, the maximum of the absorption band is at 720 nm in water and at 2300 nm in diethyl ether; while for the three polyalcohols (Fig.l), 1,Zethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (1 3PD), it is located at 570,565, and 575 nm, respectively. Although the absorption spectra of the solvated electron in these three diols have been reported, in the published report, certain discrepancies were found on the values of the radiolytic yield and the extinction coefficient of the solvated electron in these solvents. For 12ED, the extinction coefficient at the maximum of the absorption band was reported to be bx(e,-) =
No.1
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
1,2-ethanediol
1,2-propanediol
3
1,3-propanediol
Fig.1 Molecular structure of 1,2-ethanediol, 1,2-propanediol, and 1,3-propanediol.
1.4 x lo3 mol-'.m2 [9-111. The value of the extinction coefficient at maximum reported by Sauer et al. was based on a radiation chemical yield (called G value) after spur reactions for es-, (Gfi), of 0.12pmol.J-' [91. Jou and Freeman later confirmed that the product of hxby Gfi in 12ED was around 1 . 8 ~ m2.J-' [I2]. However, compared with the radiolytic yield after spur reaction determined in other solvents like methanol or ethanol (where, Gfi is around 0.21 pmo1.P' or slightly less), the e,- yield of 0.12 pmol-J-' in 12ED reported by Sauer et aZ.[91is clearly lower. Similarly, the optical absorption spectrum of the solvated electron in 12PD and 13PD was recorded by nanosecond pulse radiolysis measurements and the value of Gfihx(e,-) at the maximum of the absorption band was determined to be around 1.15x m2.J-' in both solvents as in 12ED [I3]. Using a correlation between the value of Gfi and the static electric constant of the alcohols, Jay-Gerin and Ferradini calculated the values of Gfi and hx(e,-) for the p~lyols['~'. The value of Emx(es-)at the maximum of the absorption band was estimated to be 800, 750, 650 mol-'.rn2 for 12ED, 12PD, and 13PD, re~pectively."~] Knowing the extinction coefficient, due to the kinetic signals obtained by the recently constructed picosecond pulse radiolysis system [16-181, the t'imedependent radiolytic yields of the solvated electron in these diols from the picosecond to the microsecond time range are described. A rise in the temperature induces a red shift of the solvated electron absorption spectrum. For example, in water, the absorption maximum is located around 692 nm at 274 K, 810 nm at 380 K, and 1200 nm at 673 K (350 atm) under supercritical conditions. The temperature dependence of the absorption spectra of the solvated electron has been recorded not only in water but also in alcohols. Brodsky and Tsarevsky "I1 as well as Henmann and Krebs [I9] measured the absorption
spectrum of the solvated electron in methanol and CD30D in a wide range of temperatures. Okazaki et al. reported the temperature dependence of the absorption spectra of the solvated electron in liquid diols, among them 12ED, 12PD, and 13PD, but the spectra were measured in a low temperature range (235 K I T I 3 14 K) at atmospheric pre~sure"~]. Chandrasekhar and Krebs recorded the optical absorption of the solvated electron in 12ED in the high temperature range 296 K I T I 4 5 3 K "O'. In this study, after determining the time-dependent G-value and the extinction coefficient of solvated electron in the diols, the optical spectra of the solvated electron in higher is depicted, that is, temperature range 2 9 5 K I T I 5 9 8 K for 12ED, and 2 9 5 K I T I 4 9 8 K for 12PD and 13PD, in order to study the influence of the distance between the two hydroxyl groups on the electron trapping.
2
Experimental section
1,Zethanediol (12ED, Ethylene glycol), 1,2-propanediol (12PD, propylene glycol), 1,3-propanediol (13PD) as well as 4,4'-bipyridine (44 Bpy) and methylviologen (MV2') were purchased from Wako Pure Chemical Industries, Ltd., and used as received. The nanosecond pulse radiolysis experiments were carried out at the University of Tokyo using a linear electron accelerator (energy: 35 MeV; pulse width: 10 ns) coupled with an absorption spectroscopic detection system. The dosimetry was performed with an N,O-saturated 10 mm01.L" KSCN aqueous solution, taking GE((SCN)~'-) = 5.2 x m2.J-' at 475 nm [211. The dose fluctuations were less than 5 % during a day long experiment. The high temperature high pressure optical cell was made by Taiatsu [email protected] size of the irradiation cell was fairly compact for easy setting up of the
NUCLEAR SCIENCE AND TECHNIQUES
4
optical detection system. High signalhoke ratios could be obtained because the effective diameter of the sapphire window for optical access was 6 mm and the optical path was 15mm. The cell can withstand temperatures and pressures up to 700 K and 40 MPa. The pressure was fixed at 10 MPa for all temperatures. The solution was loaded into the cell by an HPLC pump. The temperature of the sample solution was monitored by a thermocouple placed inside the cell and the pressure was adjusted with a back-pressure regulator. Picosecond pulse radiolysis measurements were performed with a pulse-and-probe method using the same facility. Details and performance of the system have been reported elsewhere "6-183. Briefly, an S-band linear accelerator with a laser photocathode rf-gun was operated at a repetition rate of 10 Hz. A femtosecond Ti:sapphire laser beam (795nm) was split by a half mirror into two equal pulses and used: as a probe analyzing light after passing through a quartz cell filled with D 2 0 for generating white light continuum and as an injector for the photocathode rf-gun after third-harmonic generation. An electron beam with a pulse duration of 3 ps (FWHM), a charge of 1 nC, and an energy of 20MeV, was produced as an irradiation source. The electron beam and the fs laser are synchronized within 2 ps (root mean square value) and an optical delay stage was employed for altering the time interval between the electron pulse and the probe light pulse. The optical path length of the quartz cell was usually 1Omm. For measurements of G(es-)ges-) in the alcohols, a kinetic signal of the hydrated electron at 700nm in pure water was recorded and under the same experimental conditions, the kinetic signal of the solvated electron (at the absorption band maximum) in an alcohol was measured:
A(e;)=E(e;).Z-c=&(e;).I.G(e;).DH,o-pdio,(1) where, A is the absorbance of the solvated electron, E is the extinction coefficient, I is the optical path length of the cell, c is the concentration of hydrated electron, G is the radiolytic yield of hydrated electron, DH20 represents the dose per pulse in water, and p is the density. At a given time, G(e; H e ; = G(e, ) .de;
1.
)Me,
1. pdiol ) (2)
Vv1.18
Since G(e,,-)E(e,,-) has been well established '22', from the above equation G(esJE(esJ is obtained for the alcohols. 3
Results and discussion
3.1 Absorption coefficient of solvated electrons 44 Bpy was used as a scavenger of the solvated electron, because of its excellent solubility, its high reactivity toward the solvated electron, as well as its fairly stable electron adducts. Different concentrations of 44 Bpy from 0.5 mmol-L-l up to 100 mmol-L-' are used to scavenge the solvated electron. The kinetics are observed at 700 and 540 nm (Figs. 2A and 2B). The kinetics observed at 700 nm are mainly due to the solvated electron, although, for the high concentrations of scavenger (20, 50, and lOOmmol-L-') a slow increase of the absorbance is observed at longer time. The decay of the solvated electron is accelerated by increasing the concentration of the scavenger due to the following reaction: e;
+ 44Bpy+44Bpyb-
(3)
The anion Bpy'- reacts very quickly with H+ to form the neutral radical BpyH': 44Bpy'-
+ H'
44BpyH'
(4)
The maximum of the absorption band of this neutral radical is located at 540 nm [231 and the extinction coefficient in aqueous solution is known to be 1300 mol-1.m2 1241 Both the solvated electron and the electron adduct of 44 Bpy absorb at 540 nm. So, at 540 nm, in a short time, the absorption just after the pulse is due to the solvated electron while at longer time the absorption is related to 44 BpyH' formed through reaction (4), which is stable for a few microseconds. From the kinetics (at 700nm) at low concentrations (0-10 mmol-L'), the rate constant ofthe reaction (3) can be deduced taking into account the residual absorbance at the end of the decay of solvated electrons which is due to the 44 BpyH;' , produced from the disproportionation of 44BpyH' or the abstraction of an H+ from the solvent. The rate constant is obtained to be 1.3 x lo9 L-mol-'.s-' (Table 1).
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
No. 1
0.25
5
I
0 20
E 0
-
0 15
m
d
em
x
0.10
2 0.05
-100
0
100
200 Time / ns
300
400
500
0
-100
100
200
300
500
400
Time / ns
Fig.2 Time profiles at 700 nm (A) and at 540 nrn (B) obtained by pulse radiolysis of 12ED solutions in the presence of different concentrations of 44 Bpy: (a) pure 12ED (b) 0.5 (c) 0.75 (d) 1 (e) 5 (010 (g) 20 (h) SO, and (i) 100 mm01.L.'.
Table 1 Properties and results obtained for the three diols and water k(e,-+S) S /L.mol-'.s-') /m~as) 12ED Bpy 1.3 x lo9 16.1 12PD Bpy 6 . 4 lo8 ~ 40.4 13PD Bpy 6.7 x lo8 39.4 Water Bpy 2.9 x lolob 0.89 a) a clear formation process of the solvated electron b) from Ref. [29] P
O
C
Dielectric &of esconstant /nm 41.4 570 27.5 5 65 35.1 575 78.4 720 was found within about 50 ps.
From the plateau observed at 540 nm (Fig. 2B), for a given quencher concentration, by assuming an extinction coefficient of 1300 mol".rn2 for 44 BpyH' as in aqueous solutions [241, the concentration of 44 BpyH' formed after the pulse is obtained. At a concentration of 100 mmol.L-', almost all solvated electrons produced by the pulse are scavenged by 44Bpy. Therefore, the extinction coefficient of the solvated electron can be deduced. In fact, the absorbance at 540 nm (at time zero) in the absence and in the presence of 100 mm01.L-l 44 Bpy is 0.32 and 0.49, respectively. According to the Beer-Lambert's law:
4,,(0
mmo1.L-l) / &-(loo
mmol X') ( 5 )
With this relation and taking into account the intensity of the absorption spectra of solvated electron, E(e; at 570 nm) = 880 mol-' em2
/rnol-'.rn2 900 f SO 970 k 50 1000 f 50 1800
G at 20011s /prnol. J0.17 0.17 0.22 0.27
'
If the pre-solvated electron is scavenged by 44 Bpy, the value 880 mol-'.m2 should be corrected to a lower value. But as mentioned above, the scavenging of pre-solvated electron was neglected by 44 Bpy. The c(es- at 570 nm) is estimated from the time profile of the solvated electron in pure 12ED. In this measurement, the dose per pulse measured using 10 mmol-L-' KSCN is 63 Gy. The absorbance in 2 cm cell at 540 nm at the end of pulse in the absence of scavenger is 0.32. A rough estimation of the radiolytic yield of the solvated electron shows that G(e,-) at the end of the pulse (-10 ns) is about 0.28 pmol.J-'. From the following relation: L ( 1 0 n s ) = &(e; at540nm).l.c
&(e; at 540 nm) / ~(44BpyH'at 540 nm) =
G /prnol.J-' 0.43 (at 3Ops) 0.35 (at 1OOps) a 0.38 (at 1OOps) a 0.44 (at 3Ops)
E
(6)
= &(e; at 540 nm) .1. G(e; at 10ns)
- Ddiol
(7)
the value of the extinction coeffkient can be deduced: &(e; at 540 nm) = 4-(lOns) =
/ ( 1 . G(e, at 10 ns) .DdiOl)
910 mol-' em2
(8)
6
NUCLEAR SCIENCE AND TECHNIQUES
Withm the errors, the values obtained by the two different methods are in good agreement. Therefore, the extinction coefficient at the maximum of the absorption band is: &(eJ at 570 nm) = 900 f 50 mol-' .m2
(9)
If it is assumed that the scavenging of pre-solvated electron by 44 Bpy is negligible, the uncertainties on this estimation are mainly due to the fluctuations of the dose per pulse and to the error on the value of the extinction coefficient of BpyH'. With similar procedures, the rate constant of the solvated electron scavenging by 44 Bpy and the extinction coefficients of the solvated electron in 12PD and 13PD are determined. The results are shown in Table 1. The extinction coefficients of the solvated electron are 900, 970,and 1000 mol-'.m2, in these three solvents 12ED, 12PD, and 13PD, respectively. These values are smaller than the reported value, 1400 mol-'-m2for e[ in 12ED [91, but slightly higher than those proposed by Jay-Gerin et al. [15], which are 800, 750, and 650 mol-'.m2 for 12ED,12PD,and 13PD,respectively. Fig.3 shows the absorption spectra of the solvated electron in various solvents. Compared to the solvated electron in water and simple alcohols, the maximum of absorption bands for the polyols is located at higher energies while their extinction coefficients are somewhat lower. 2.0
VOl. 18
after 30 ps and the kinetics observed at this wavelength is only due to the spur reactions. Fig.4 (Top) shows G(e,-) in 12ED as a function of time from about 30 ps to 1 ps. There are two parts: curve (a) obtained by picosecond pulse radiolysis and curve (b) recorded by conventional nanosecond pulse radiolysis. Although two different independent methods are used and the measurements cannot cover all time regions (no data from 1 ns to a few tens of nanoseconds), it seems that curves (a) and (b) match each other well. For comparison, the data obtained for the hydrated electron in previous study (Fig.4, curves c) is plotted [221. At subnanosecond time range, the radiolytic yield of the solvated electron in 12ED and in water are very close, but at longer time range, the yield of solvated electron in 12ED is much lower than in water. The yield of the solvated electron in 12ED which is about 0.36 pmo1.P' at 1 ns decreases strongly to the value of 0.17 pmol-J-' at 200 ns. In the case of water for the same time range, the yield changes from 0.37 to 0.27 pmol-S'. That means that the decay of the solvated electron through the spur reactions is more efficient in 12ED than in water. As the escape from spur reactions depends on the diffusion constant (inverse of viscosity) and as the spur reactions are not all diffusion controlled; the high viscosity of solvents like diols avoid the escape of solvated electrons from the spur reactions. Moreover, it is to be reminded that in alcohols, the solvated electron can react with the solvent following a reaction of pseudo-first order ['":
1.5 N
E
-8 0
In the case of methanol, the rate constant of reaction (10) has been reported to be 8.5 x lo3 '261 or 1.1 x lo4L.mol-'.s-' [271, while for ethanol it is 3.8 x lo4 L-mol-1 .s-1 [28]. These values are much higher than the equivalent reaction for water, which is 19 L-mol-'-s-'
1.0
. 0 r
0
0.5
01
I
300 400
1
1
500 600
1
700
1
800
I
"291
900 1000
llnm
Fig3 Comparison of the absorption spectra of the solvated electrons in various solvents at mom temperature.
3.2 Time dependent radiolytic yield of solvated electrons According to the literature, in 12ED at the wavelength of 570 nm, there is no solvation dynamics effect
Similarly, the time-dependent yield of the solvated electron in 12PD and 13PD can be obtained, as shown in Fig. 4 (Middle and Bottom). In contrast to the case of 12ED,for these two solvents at picosecond time range, no decay of the solvated electron is observed. Moreover, the decay of the solvated electron in the nanosecond time range is faster in 12PD than in 13PD.And G(e,-) can be deduced at 100 ps, 0.35 and
No.1
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
0.38 pmol.J-’, and G(e[) at 200ns, 0.17 and 0.22 pmol.J-’, for 12PD and 13PD, respectively (Table 1). The dielectric constant and the viscosity of the two latter solvents are closed but different from those of 12ED. For comparison, the data in water are also shown in Table 1.
I
.
I
’
I
’
I
’
I
I
7 1
1
0 15
0 12
0 09
U 5
0 06 04 03
0 03
02
01 0 04
03 02
01
0.12
-
0.08
-
0.04
-
0 04 03 02
01
1
0.00 -
0 10-11
1010
10-9
108
107
106
0.24
Time
Fig.4 Time dependence of the radiolytic yield of the solvated electron in 12ED (Top), in 12PD (Middle), and in 13PD (Bottom). (a) picosecond pulse radiolysis measurements, (b) nanosecond pulse radiolysis studies, (c) time-dependent G value of the hydrated electron repxted in the previous study.
3.3 Temperature-dependentabsorption spectra of the solvated electrons Fig.5 shows the temperature dependence of the absorption spectrum of the solvated electron in 12ED, 12PD, and 13PD. At a given temperature, the shape of the spectrum in one solvent is independent of time. The absorption band maximum at room temperature is around 570, 565, and 575 nm, for 12ED, 12PD, and 13PD, respectively. Those values are in agreement with the reported ones. By increasing the temperature, the decays increase at a rapid pace and most of the solvated electrons disappear within the electron pulse due to the geminate recombination, hence a drop in the measured absorbance. However, the maximum of the solvated electron absorption band shifts to the longer
0.20
-
0.16
-
0.12
-
0.08
-
0.04
400
500
600
700
800
900
llnm
FigJ Absorption spectra of the solvated electron in 12ED, 12PD, and 13PD under 10 MPa at different temperatures. Pulse duration: 10 ns, dose: 15 Gy, optical path: 15 mm.
wavelength with the temperature rise. The transition energy at the absorption maximum plotted as a function of temperature is correctly fitted by a straight line for each solvent (Fig.6). From the slope of the curves, the temperature coefficient (dEmx/dT)is determined to be equal to -2.5 x 10” eV.R’ in 12ED, -3.1 x 10”
8
NUCLEAR SCIENCE AND TECHNIQUES
eV.K-’ in 12PD, and -2.8 x 10” eV.K-’ in 13PD. At ~’ the vallower temperature, Okazaki et ~ 2 1 . ‘ ~reported ues of -2.7 x 10” and -3.0 x eV.R’, for 12PD and 13PD, respectively, but if their data is added in Fig.6, a good agreement is noted with the results, and a common temperature coefficient of -2.9 x eV-K” in 12PD and -2.8 x 10” eV-R’ in 13PD is deduced. The latter values are very close to each other, but lower than the value in methanol (-3 x 10” eV-K-l ‘I9’) and in 1-propanol (-3.5 x 10” eV.R’). To conclude, the results show that even if the behavior of the solvated electron in these three polyols as a function of temperature is close, a few differences exist. As the length of the aliphatic chain and the number of hydroxyl groups are the same for both solvents, the observations emphasize the significant influence of the distance between the two OH groups on the behavior of the trapped electron. At room temperature, the energy of the absorption maximum is higher in 12PD than in 13PD and the absorption band of the solvated electron is narrower in 12PD than in 13PD. These observations indicate that the two neighboring OH groups create deeper electron traps and a narrower distribution of traps in 12PD compared
Vol. 18
to 13PD. These results are in agreement with those reported for 12ED at high temperature and for 12ED and 13PD glasses. However, the traps in 12PD appear less deep than in 12ED since the energy of the absorption maximum of the solvated electron measured at a given temperature is lower in 12PD than in 12ED, which shows an influence of the additional methyl group on the solvent structure, in particular on the created three-dimensional networks of hydrogen-bonded molecules. Moreover, an increase in temperature affects more greatly the electron trapping in 12PD than in 13PD since the temperature coefficient is more negative and the shape of the spectrum changes only in 12PD. Talung into account that the decrease in viscosity versus temperature is also faster in 12PD compared to 13PD, the different behavior of the two solvents results from larger modifications of the solvent structure and molecular interactions for 12PD than for 13PD. In order to obtain a better insight into the solvent molecular structure, femtosecond experiments on the solvation dynamics of the electron in the propanediols are underway.
Acknowledgments The authors are grateful to Mr. T. Ueda and Mr. K. Yoshii, and Prof. M. Uesaka for their technical assistance in experiments and encouragement. They are also thankful to Dr. H. He and Dr. Z. Han for their assistance in several experiments. This study was partly entrusted by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japanese Government, as a “Fundamental R&D program on water chemistry of supercritical pressure water under radiation field”.
References 1 200
300
400
500
600
700
Temperature / K
Fig.6 Energy of the maximum of the solvated electron absorption band ( E d as a function of temperature in different solvents: 12PD (a)this study, (*)[131; 13PD (Q) this study, (*) [13]; 12ED (0) [13], (A) [201, (0)this study; CD30D (0) 1191; I-propanol (m), unpublished; water (V)and D20 (A) ~301.
Hart E J, Boag J W. J Am Chem SOC, 1962, 84:
4090-4095. 2
Boag J W, Hart E J. Nature, 1963,197: 45-46.
3
Keene J P. Nature, 1963,197: 47.
4
Hart E J, Anbar M. The Hydrated Electron, New York
Wiley-Interscience, 1970.
5
Dorfman L M, Jou F Y. Ber. Bunsen-Ges, 1971, 75:
68 1-685.
No.1
6
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. . Dorfman L M, Jou F Y. “Optical absorption spectrum of
19 Henmann V, Krebs P. J Phys Chem, 1995,W: 6794-6800.
tems.” In Electrons in Fluids. Ed. Jortner J, Kestner N R.
20 Chandrasekhar N, Krebs P. J Chem Phys, 2000, 112,
Ferradini C, Jay-Gerin J P. Radiat Phys Chem, 1996, 48: 473-480.
8
Belloni J, Marignier J L. Radiat Phys Chem, Int J Radiat Appl Instrum Part C, 1989,M: 157-171.
9
2005,31: 261-272.
the solvated electron in ethers and in binary liquid sysNew-York: Springer, 1972,447-457. 7
9
Sauer M C, Arai S, Dorfman L M. J Chem Phys, 1965,42: 708-712.
10 Brodsky A M , Tsarevsky A V. Inst Elektrokhim, 1975,222: 1365-1368. 11 Brodsky A M, Tsarevsky A V. J Phys Chem, 1984, 88: 3790-3799. 12 Jou F Y, Freeman G R. Can. J Chem, 1979,59: 591-597. 13 Okazaki K, Idriss-Ali K M, Freeman G R. Can. J Chem, 1984,62: 2223-2229. 14 Jay-Gerin J P, Ferradini C. Radiat Phys Chem, 1989, 33: 251-253, 15 Jay-Gerin J P, Ferradini C. J Chim Phys, 1994, 91:
173-187. 16 Muroya Y, Watanabe T, Wu G et al. Radiat Phys Chem, 2001,60 : 307-312. 17 Muroya Y, Lin M, Watanabe T, et al. Nucl Instr Meth, 2002, A4891 554-562. 18 Muroya Y, Lin M, Iijima H, et al. Res Chem Intermed,
5910-5914. 21 Buxton G V, Stuart C R. J Chem SOC,Faraday Trans, 1995, 91: 279-281. 22 Muroya Y, Lin M, Wu G et al. Radiat Phys Chem, 2005, 72: 169-172. 23 Elisei F, Mazzucato U, Comer H, et al. J Photochem Photobiol, A: Chemistry, 1989,SO: 209-219. 24 SimiC M, Ebert M. Int. J Radiat Phys Chem, 1971,3 : 259. 25 Ferradini C, Jay-Gerin J P. Radiat Phys Chem, 1996, 48: 473-480. 26 Johnson D W, Salmon G A. Radiat Phys Chem, 1977, 10: 294-296. 27 Getoff N, Ritter A, Schworer F. J Chem SOC,Faraday Trans. 1, 1983,79 : 2389-2404. 28 Han Z, Katsumura Y, Lin M, et aE. Chem Phys Lett, 2005, 404: 267-27 1. 29 Buxton G V, Greenstock C L, Helman W P, et al. J Phys Chem Ref Data, 1988,17: 513. 30 Wu G, Katsumura Y, Muroya Y, et al. Chem Phys Lett,
2000,325: 531-536. 31 Soroushian B, Lampre I, Belloni J, et al. Radiat Phys Chem, 2005,72: 111-118.
ScienceDirect
NUCLEAR SCIENCE AND TECHNIQUES
Nuclear Science and Techniques, Vol.18, No 1 (2007) 2-9
Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols Mingzhang LIN Mehran MOSTAFAVI Yusa MUROYA Isabelle LAMPRE * Yosuke KATSUMURA l V 3 , * ('Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, Hongo 7-3-1,Bunkyo-ku, Tokyo 113-8656, Japan; 'Laboratoire de Chimie Physique/ELYSE, UMR 8000 CNRS / Universite' Paris-Sud, Centre d'Orsay, BBt. 349, 91405 Orsay Cedex, France; 'Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata Shirane, Tokaimura. Nakagun, Ibaraki 31 9-1188, Japan)
Abstract The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-'.m* for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolfic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.
Key words Polyols, Solvated electrons, Picosecond pulse radiolysis
CLC number 0 6 2 1.25
1
Introduction
The chemical effects of ionizing radiation on liquids have been extensively studied for decades in steady state and pulse regimes. Among the radicals produced by irradiation, the solvated electron (e,-) has been the subject of a huge amount of publications. Since the first measurements in water, the optical absorption of the solvated electron has been observed in more than a hundred solvents. Due to this property, the reactivity of the solvated electron has been studied by transient absorption measurements in many solvents, such as water or alcohols, using pulse radiolysis techniques [lF8'. The properties of the solvated electron depend on * Corresponding author, Email:[email protected],ac.jp
several factors, such as the solvent, the temperature, and the pressure. For instance, at room temperature, the maximum of the absorption band is at 720 nm in water and at 2300 nm in diethyl ether; while for the three polyalcohols (Fig.l), 1,Zethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (1 3PD), it is located at 570,565, and 575 nm, respectively. Although the absorption spectra of the solvated electron in these three diols have been reported, in the published report, certain discrepancies were found on the values of the radiolytic yield and the extinction coefficient of the solvated electron in these solvents. For 12ED, the extinction coefficient at the maximum of the absorption band was reported to be bx(e,-) =
No.1
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
1,2-ethanediol
1,2-propanediol
3
1,3-propanediol
Fig.1 Molecular structure of 1,2-ethanediol, 1,2-propanediol, and 1,3-propanediol.
1.4 x lo3 mol-'.m2 [9-111. The value of the extinction coefficient at maximum reported by Sauer et al. was based on a radiation chemical yield (called G value) after spur reactions for es-, (Gfi), of 0.12pmol.J-' [91. Jou and Freeman later confirmed that the product of hxby Gfi in 12ED was around 1 . 8 ~ m2.J-' [I2]. However, compared with the radiolytic yield after spur reaction determined in other solvents like methanol or ethanol (where, Gfi is around 0.21 pmo1.P' or slightly less), the e,- yield of 0.12 pmol-J-' in 12ED reported by Sauer et aZ.[91is clearly lower. Similarly, the optical absorption spectrum of the solvated electron in 12PD and 13PD was recorded by nanosecond pulse radiolysis measurements and the value of Gfihx(e,-) at the maximum of the absorption band was determined to be around 1.15x m2.J-' in both solvents as in 12ED [I3]. Using a correlation between the value of Gfi and the static electric constant of the alcohols, Jay-Gerin and Ferradini calculated the values of Gfi and hx(e,-) for the p~lyols['~'. The value of Emx(es-)at the maximum of the absorption band was estimated to be 800, 750, 650 mol-'.rn2 for 12ED, 12PD, and 13PD, re~pectively."~] Knowing the extinction coefficient, due to the kinetic signals obtained by the recently constructed picosecond pulse radiolysis system [16-181, the t'imedependent radiolytic yields of the solvated electron in these diols from the picosecond to the microsecond time range are described. A rise in the temperature induces a red shift of the solvated electron absorption spectrum. For example, in water, the absorption maximum is located around 692 nm at 274 K, 810 nm at 380 K, and 1200 nm at 673 K (350 atm) under supercritical conditions. The temperature dependence of the absorption spectra of the solvated electron has been recorded not only in water but also in alcohols. Brodsky and Tsarevsky "I1 as well as Henmann and Krebs [I9] measured the absorption
spectrum of the solvated electron in methanol and CD30D in a wide range of temperatures. Okazaki et al. reported the temperature dependence of the absorption spectra of the solvated electron in liquid diols, among them 12ED, 12PD, and 13PD, but the spectra were measured in a low temperature range (235 K I T I 3 14 K) at atmospheric pre~sure"~]. Chandrasekhar and Krebs recorded the optical absorption of the solvated electron in 12ED in the high temperature range 296 K I T I 4 5 3 K "O'. In this study, after determining the time-dependent G-value and the extinction coefficient of solvated electron in the diols, the optical spectra of the solvated electron in higher is depicted, that is, temperature range 2 9 5 K I T I 5 9 8 K for 12ED, and 2 9 5 K I T I 4 9 8 K for 12PD and 13PD, in order to study the influence of the distance between the two hydroxyl groups on the electron trapping.
2
Experimental section
1,Zethanediol (12ED, Ethylene glycol), 1,2-propanediol (12PD, propylene glycol), 1,3-propanediol (13PD) as well as 4,4'-bipyridine (44 Bpy) and methylviologen (MV2') were purchased from Wako Pure Chemical Industries, Ltd., and used as received. The nanosecond pulse radiolysis experiments were carried out at the University of Tokyo using a linear electron accelerator (energy: 35 MeV; pulse width: 10 ns) coupled with an absorption spectroscopic detection system. The dosimetry was performed with an N,O-saturated 10 mm01.L" KSCN aqueous solution, taking GE((SCN)~'-) = 5.2 x m2.J-' at 475 nm [211. The dose fluctuations were less than 5 % during a day long experiment. The high temperature high pressure optical cell was made by Taiatsu [email protected] size of the irradiation cell was fairly compact for easy setting up of the
NUCLEAR SCIENCE AND TECHNIQUES
4
optical detection system. High signalhoke ratios could be obtained because the effective diameter of the sapphire window for optical access was 6 mm and the optical path was 15mm. The cell can withstand temperatures and pressures up to 700 K and 40 MPa. The pressure was fixed at 10 MPa for all temperatures. The solution was loaded into the cell by an HPLC pump. The temperature of the sample solution was monitored by a thermocouple placed inside the cell and the pressure was adjusted with a back-pressure regulator. Picosecond pulse radiolysis measurements were performed with a pulse-and-probe method using the same facility. Details and performance of the system have been reported elsewhere "6-183. Briefly, an S-band linear accelerator with a laser photocathode rf-gun was operated at a repetition rate of 10 Hz. A femtosecond Ti:sapphire laser beam (795nm) was split by a half mirror into two equal pulses and used: as a probe analyzing light after passing through a quartz cell filled with D 2 0 for generating white light continuum and as an injector for the photocathode rf-gun after third-harmonic generation. An electron beam with a pulse duration of 3 ps (FWHM), a charge of 1 nC, and an energy of 20MeV, was produced as an irradiation source. The electron beam and the fs laser are synchronized within 2 ps (root mean square value) and an optical delay stage was employed for altering the time interval between the electron pulse and the probe light pulse. The optical path length of the quartz cell was usually 1Omm. For measurements of G(es-)ges-) in the alcohols, a kinetic signal of the hydrated electron at 700nm in pure water was recorded and under the same experimental conditions, the kinetic signal of the solvated electron (at the absorption band maximum) in an alcohol was measured:
A(e;)=E(e;).Z-c=&(e;).I.G(e;).DH,o-pdio,(1) where, A is the absorbance of the solvated electron, E is the extinction coefficient, I is the optical path length of the cell, c is the concentration of hydrated electron, G is the radiolytic yield of hydrated electron, DH20 represents the dose per pulse in water, and p is the density. At a given time, G(e; H e ; = G(e, ) .de;
1.
)Me,
1. pdiol ) (2)
Vv1.18
Since G(e,,-)E(e,,-) has been well established '22', from the above equation G(esJE(esJ is obtained for the alcohols. 3
Results and discussion
3.1 Absorption coefficient of solvated electrons 44 Bpy was used as a scavenger of the solvated electron, because of its excellent solubility, its high reactivity toward the solvated electron, as well as its fairly stable electron adducts. Different concentrations of 44 Bpy from 0.5 mmol-L-l up to 100 mmol-L-' are used to scavenge the solvated electron. The kinetics are observed at 700 and 540 nm (Figs. 2A and 2B). The kinetics observed at 700 nm are mainly due to the solvated electron, although, for the high concentrations of scavenger (20, 50, and lOOmmol-L-') a slow increase of the absorbance is observed at longer time. The decay of the solvated electron is accelerated by increasing the concentration of the scavenger due to the following reaction: e;
+ 44Bpy+44Bpyb-
(3)
The anion Bpy'- reacts very quickly with H+ to form the neutral radical BpyH': 44Bpy'-
+ H'
44BpyH'
(4)
The maximum of the absorption band of this neutral radical is located at 540 nm [231 and the extinction coefficient in aqueous solution is known to be 1300 mol-1.m2 1241 Both the solvated electron and the electron adduct of 44 Bpy absorb at 540 nm. So, at 540 nm, in a short time, the absorption just after the pulse is due to the solvated electron while at longer time the absorption is related to 44 BpyH' formed through reaction (4), which is stable for a few microseconds. From the kinetics (at 700nm) at low concentrations (0-10 mmol-L'), the rate constant ofthe reaction (3) can be deduced taking into account the residual absorbance at the end of the decay of solvated electrons which is due to the 44 BpyH;' , produced from the disproportionation of 44BpyH' or the abstraction of an H+ from the solvent. The rate constant is obtained to be 1.3 x lo9 L-mol-'.s-' (Table 1).
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
No. 1
0.25
5
I
0 20
E 0
-
0 15
m
d
em
x
0.10
2 0.05
-100
0
100
200 Time / ns
300
400
500
0
-100
100
200
300
500
400
Time / ns
Fig.2 Time profiles at 700 nm (A) and at 540 nrn (B) obtained by pulse radiolysis of 12ED solutions in the presence of different concentrations of 44 Bpy: (a) pure 12ED (b) 0.5 (c) 0.75 (d) 1 (e) 5 (010 (g) 20 (h) SO, and (i) 100 mm01.L.'.
Table 1 Properties and results obtained for the three diols and water k(e,-+S) S /L.mol-'.s-') /m~as) 12ED Bpy 1.3 x lo9 16.1 12PD Bpy 6 . 4 lo8 ~ 40.4 13PD Bpy 6.7 x lo8 39.4 Water Bpy 2.9 x lolob 0.89 a) a clear formation process of the solvated electron b) from Ref. [29] P
O
C
Dielectric &of esconstant /nm 41.4 570 27.5 5 65 35.1 575 78.4 720 was found within about 50 ps.
From the plateau observed at 540 nm (Fig. 2B), for a given quencher concentration, by assuming an extinction coefficient of 1300 mol".rn2 for 44 BpyH' as in aqueous solutions [241, the concentration of 44 BpyH' formed after the pulse is obtained. At a concentration of 100 mmol.L-', almost all solvated electrons produced by the pulse are scavenged by 44Bpy. Therefore, the extinction coefficient of the solvated electron can be deduced. In fact, the absorbance at 540 nm (at time zero) in the absence and in the presence of 100 mm01.L-l 44 Bpy is 0.32 and 0.49, respectively. According to the Beer-Lambert's law:
4,,(0
mmo1.L-l) / &-(loo
mmol X') ( 5 )
With this relation and taking into account the intensity of the absorption spectra of solvated electron, E(e; at 570 nm) = 880 mol-' em2
/rnol-'.rn2 900 f SO 970 k 50 1000 f 50 1800
G at 20011s /prnol. J0.17 0.17 0.22 0.27
'
If the pre-solvated electron is scavenged by 44 Bpy, the value 880 mol-'.m2 should be corrected to a lower value. But as mentioned above, the scavenging of pre-solvated electron was neglected by 44 Bpy. The c(es- at 570 nm) is estimated from the time profile of the solvated electron in pure 12ED. In this measurement, the dose per pulse measured using 10 mmol-L-' KSCN is 63 Gy. The absorbance in 2 cm cell at 540 nm at the end of pulse in the absence of scavenger is 0.32. A rough estimation of the radiolytic yield of the solvated electron shows that G(e,-) at the end of the pulse (-10 ns) is about 0.28 pmol.J-'. From the following relation: L ( 1 0 n s ) = &(e; at540nm).l.c
&(e; at 540 nm) / ~(44BpyH'at 540 nm) =
G /prnol.J-' 0.43 (at 3Ops) 0.35 (at 1OOps) a 0.38 (at 1OOps) a 0.44 (at 3Ops)
E
(6)
= &(e; at 540 nm) .1. G(e; at 10ns)
- Ddiol
(7)
the value of the extinction coeffkient can be deduced: &(e; at 540 nm) = 4-(lOns) =
/ ( 1 . G(e, at 10 ns) .DdiOl)
910 mol-' em2
(8)
6
NUCLEAR SCIENCE AND TECHNIQUES
Withm the errors, the values obtained by the two different methods are in good agreement. Therefore, the extinction coefficient at the maximum of the absorption band is: &(eJ at 570 nm) = 900 f 50 mol-' .m2
(9)
If it is assumed that the scavenging of pre-solvated electron by 44 Bpy is negligible, the uncertainties on this estimation are mainly due to the fluctuations of the dose per pulse and to the error on the value of the extinction coefficient of BpyH'. With similar procedures, the rate constant of the solvated electron scavenging by 44 Bpy and the extinction coefficients of the solvated electron in 12PD and 13PD are determined. The results are shown in Table 1. The extinction coefficients of the solvated electron are 900, 970,and 1000 mol-'.m2, in these three solvents 12ED, 12PD, and 13PD, respectively. These values are smaller than the reported value, 1400 mol-'-m2for e[ in 12ED [91, but slightly higher than those proposed by Jay-Gerin et al. [15], which are 800, 750, and 650 mol-'.m2 for 12ED,12PD,and 13PD,respectively. Fig.3 shows the absorption spectra of the solvated electron in various solvents. Compared to the solvated electron in water and simple alcohols, the maximum of absorption bands for the polyols is located at higher energies while their extinction coefficients are somewhat lower. 2.0
VOl. 18
after 30 ps and the kinetics observed at this wavelength is only due to the spur reactions. Fig.4 (Top) shows G(e,-) in 12ED as a function of time from about 30 ps to 1 ps. There are two parts: curve (a) obtained by picosecond pulse radiolysis and curve (b) recorded by conventional nanosecond pulse radiolysis. Although two different independent methods are used and the measurements cannot cover all time regions (no data from 1 ns to a few tens of nanoseconds), it seems that curves (a) and (b) match each other well. For comparison, the data obtained for the hydrated electron in previous study (Fig.4, curves c) is plotted [221. At subnanosecond time range, the radiolytic yield of the solvated electron in 12ED and in water are very close, but at longer time range, the yield of solvated electron in 12ED is much lower than in water. The yield of the solvated electron in 12ED which is about 0.36 pmo1.P' at 1 ns decreases strongly to the value of 0.17 pmol-J-' at 200 ns. In the case of water for the same time range, the yield changes from 0.37 to 0.27 pmol-S'. That means that the decay of the solvated electron through the spur reactions is more efficient in 12ED than in water. As the escape from spur reactions depends on the diffusion constant (inverse of viscosity) and as the spur reactions are not all diffusion controlled; the high viscosity of solvents like diols avoid the escape of solvated electrons from the spur reactions. Moreover, it is to be reminded that in alcohols, the solvated electron can react with the solvent following a reaction of pseudo-first order ['":
1.5 N
E
-8 0
In the case of methanol, the rate constant of reaction (10) has been reported to be 8.5 x lo3 '261 or 1.1 x lo4L.mol-'.s-' [271, while for ethanol it is 3.8 x lo4 L-mol-1 .s-1 [28]. These values are much higher than the equivalent reaction for water, which is 19 L-mol-'-s-'
1.0
. 0 r
0
0.5
01
I
300 400
1
1
500 600
1
700
1
800
I
"291
900 1000
llnm
Fig3 Comparison of the absorption spectra of the solvated electrons in various solvents at mom temperature.
3.2 Time dependent radiolytic yield of solvated electrons According to the literature, in 12ED at the wavelength of 570 nm, there is no solvation dynamics effect
Similarly, the time-dependent yield of the solvated electron in 12PD and 13PD can be obtained, as shown in Fig. 4 (Middle and Bottom). In contrast to the case of 12ED,for these two solvents at picosecond time range, no decay of the solvated electron is observed. Moreover, the decay of the solvated electron in the nanosecond time range is faster in 12PD than in 13PD.And G(e,-) can be deduced at 100 ps, 0.35 and
No.1
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. .
0.38 pmol.J-’, and G(e[) at 200ns, 0.17 and 0.22 pmol.J-’, for 12PD and 13PD, respectively (Table 1). The dielectric constant and the viscosity of the two latter solvents are closed but different from those of 12ED. For comparison, the data in water are also shown in Table 1.
I
.
I
’
I
’
I
’
I
I
7 1
1
0 15
0 12
0 09
U 5
0 06 04 03
0 03
02
01 0 04
03 02
01
0.12
-
0.08
-
0.04
-
0 04 03 02
01
1
0.00 -
0 10-11
1010
10-9
108
107
106
0.24
Time
Fig.4 Time dependence of the radiolytic yield of the solvated electron in 12ED (Top), in 12PD (Middle), and in 13PD (Bottom). (a) picosecond pulse radiolysis measurements, (b) nanosecond pulse radiolysis studies, (c) time-dependent G value of the hydrated electron repxted in the previous study.
3.3 Temperature-dependentabsorption spectra of the solvated electrons Fig.5 shows the temperature dependence of the absorption spectrum of the solvated electron in 12ED, 12PD, and 13PD. At a given temperature, the shape of the spectrum in one solvent is independent of time. The absorption band maximum at room temperature is around 570, 565, and 575 nm, for 12ED, 12PD, and 13PD, respectively. Those values are in agreement with the reported ones. By increasing the temperature, the decays increase at a rapid pace and most of the solvated electrons disappear within the electron pulse due to the geminate recombination, hence a drop in the measured absorbance. However, the maximum of the solvated electron absorption band shifts to the longer
0.20
-
0.16
-
0.12
-
0.08
-
0.04
400
500
600
700
800
900
llnm
FigJ Absorption spectra of the solvated electron in 12ED, 12PD, and 13PD under 10 MPa at different temperatures. Pulse duration: 10 ns, dose: 15 Gy, optical path: 15 mm.
wavelength with the temperature rise. The transition energy at the absorption maximum plotted as a function of temperature is correctly fitted by a straight line for each solvent (Fig.6). From the slope of the curves, the temperature coefficient (dEmx/dT)is determined to be equal to -2.5 x 10” eV.R’ in 12ED, -3.1 x 10”
8
NUCLEAR SCIENCE AND TECHNIQUES
eV.K-’ in 12PD, and -2.8 x 10” eV.K-’ in 13PD. At ~’ the vallower temperature, Okazaki et ~ 2 1 . ‘ ~reported ues of -2.7 x 10” and -3.0 x eV.R’, for 12PD and 13PD, respectively, but if their data is added in Fig.6, a good agreement is noted with the results, and a common temperature coefficient of -2.9 x eV-K” in 12PD and -2.8 x 10” eV-R’ in 13PD is deduced. The latter values are very close to each other, but lower than the value in methanol (-3 x 10” eV-K-l ‘I9’) and in 1-propanol (-3.5 x 10” eV.R’). To conclude, the results show that even if the behavior of the solvated electron in these three polyols as a function of temperature is close, a few differences exist. As the length of the aliphatic chain and the number of hydroxyl groups are the same for both solvents, the observations emphasize the significant influence of the distance between the two OH groups on the behavior of the trapped electron. At room temperature, the energy of the absorption maximum is higher in 12PD than in 13PD and the absorption band of the solvated electron is narrower in 12PD than in 13PD. These observations indicate that the two neighboring OH groups create deeper electron traps and a narrower distribution of traps in 12PD compared
Vol. 18
to 13PD. These results are in agreement with those reported for 12ED at high temperature and for 12ED and 13PD glasses. However, the traps in 12PD appear less deep than in 12ED since the energy of the absorption maximum of the solvated electron measured at a given temperature is lower in 12PD than in 12ED, which shows an influence of the additional methyl group on the solvent structure, in particular on the created three-dimensional networks of hydrogen-bonded molecules. Moreover, an increase in temperature affects more greatly the electron trapping in 12PD than in 13PD since the temperature coefficient is more negative and the shape of the spectrum changes only in 12PD. Talung into account that the decrease in viscosity versus temperature is also faster in 12PD compared to 13PD, the different behavior of the two solvents results from larger modifications of the solvent structure and molecular interactions for 12PD than for 13PD. In order to obtain a better insight into the solvent molecular structure, femtosecond experiments on the solvation dynamics of the electron in the propanediols are underway.
Acknowledgments The authors are grateful to Mr. T. Ueda and Mr. K. Yoshii, and Prof. M. Uesaka for their technical assistance in experiments and encouragement. They are also thankful to Dr. H. He and Dr. Z. Han for their assistance in several experiments. This study was partly entrusted by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japanese Government, as a “Fundamental R&D program on water chemistry of supercritical pressure water under radiation field”.
References 1 200
300
400
500
600
700
Temperature / K
Fig.6 Energy of the maximum of the solvated electron absorption band ( E d as a function of temperature in different solvents: 12PD (a)this study, (*)[131; 13PD (Q) this study, (*) [13]; 12ED (0) [13], (A) [201, (0)this study; CD30D (0) 1191; I-propanol (m), unpublished; water (V)and D20 (A) ~301.
Hart E J, Boag J W. J Am Chem SOC, 1962, 84:
4090-4095. 2
Boag J W, Hart E J. Nature, 1963,197: 45-46.
3
Keene J P. Nature, 1963,197: 47.
4
Hart E J, Anbar M. The Hydrated Electron, New York
Wiley-Interscience, 1970.
5
Dorfman L M, Jou F Y. Ber. Bunsen-Ges, 1971, 75:
68 1-685.
No.1
6
Mingzhang LIN et al.: Time-dependent radiolytic yields at room temperature and temperature dependent absorption.. . Dorfman L M, Jou F Y. “Optical absorption spectrum of
19 Henmann V, Krebs P. J Phys Chem, 1995,W: 6794-6800.
tems.” In Electrons in Fluids. Ed. Jortner J, Kestner N R.
20 Chandrasekhar N, Krebs P. J Chem Phys, 2000, 112,
Ferradini C, Jay-Gerin J P. Radiat Phys Chem, 1996, 48: 473-480.
8
Belloni J, Marignier J L. Radiat Phys Chem, Int J Radiat Appl Instrum Part C, 1989,M: 157-171.
9
2005,31: 261-272.
the solvated electron in ethers and in binary liquid sysNew-York: Springer, 1972,447-457. 7
9
Sauer M C, Arai S, Dorfman L M. J Chem Phys, 1965,42: 708-712.
10 Brodsky A M , Tsarevsky A V. Inst Elektrokhim, 1975,222: 1365-1368. 11 Brodsky A M, Tsarevsky A V. J Phys Chem, 1984, 88: 3790-3799. 12 Jou F Y, Freeman G R. Can. J Chem, 1979,59: 591-597. 13 Okazaki K, Idriss-Ali K M, Freeman G R. Can. J Chem, 1984,62: 2223-2229. 14 Jay-Gerin J P, Ferradini C. Radiat Phys Chem, 1989, 33: 251-253, 15 Jay-Gerin J P, Ferradini C. J Chim Phys, 1994, 91:
173-187. 16 Muroya Y, Watanabe T, Wu G et al. Radiat Phys Chem, 2001,60 : 307-312. 17 Muroya Y, Lin M, Watanabe T, et al. Nucl Instr Meth, 2002, A4891 554-562. 18 Muroya Y, Lin M, Iijima H, et al. Res Chem Intermed,
5910-5914. 21 Buxton G V, Stuart C R. J Chem SOC,Faraday Trans, 1995, 91: 279-281. 22 Muroya Y, Lin M, Wu G et al. Radiat Phys Chem, 2005, 72: 169-172. 23 Elisei F, Mazzucato U, Comer H, et al. J Photochem Photobiol, A: Chemistry, 1989,SO: 209-219. 24 SimiC M, Ebert M. Int. J Radiat Phys Chem, 1971,3 : 259. 25 Ferradini C, Jay-Gerin J P. Radiat Phys Chem, 1996, 48: 473-480. 26 Johnson D W, Salmon G A. Radiat Phys Chem, 1977, 10: 294-296. 27 Getoff N, Ritter A, Schworer F. J Chem SOC,Faraday Trans. 1, 1983,79 : 2389-2404. 28 Han Z, Katsumura Y, Lin M, et aE. Chem Phys Lett, 2005, 404: 267-27 1. 29 Buxton G V, Greenstock C L, Helman W P, et al. J Phys Chem Ref Data, 1988,17: 513. 30 Wu G, Katsumura Y, Muroya Y, et al. Chem Phys Lett,
2000,325: 531-536. 31 Soroushian B, Lampre I, Belloni J, et al. Radiat Phys Chem, 2005,72: 111-118.