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Study of chemiluminescence in O + NO elementary reaction by a crossed beam technique
15 May 1978
CHEMICAL PHYSICS LE-ITERS
Volume 56, number 1
STUDY OF CHEMILUMINESCENCE
IN 0 -I-NO ELEMENTARY
REACI’ION
BY A CROSSED BEAM TECHNIQUE Toshio MASAI, TSURIO~UMASUI, Hideaki NAKANE, ichiro HANAZAKi and Keiji KUWATA Department of Chemistry, Faculty of Science, Osahz UniveWty. Toyonaka, Osaka 560. Japan Received 15 February
1978
Chemihnninescent spectra of nitrogen dioxide in the visiile region have been observed in the 0 f NO elementary reaction by a crossed beam technique_ Dependences of the emission intensity on both the nitric oxide and atomic oxygen fluxintensities were fti order, and the emission was concentrated near the crossing point. These results show that the cherniluminescence observed is due to the chemically excited NOa formed in the binary reaction between NO and 0.
1. Introduction The chemihuninescent reaction of nitric oxide with atomic oxygen has been of much interest because of its major role in stratospheric reactions and of its importance as a standard in the determination of emission rates. There have been extensive investigations and numerous pioneering works in this reaction system [l-9]. The emission due to the 0 + NO binary reaction at low pressures has been observed mainly by discharge flow methods [lOI _ Becker et al. [ll] , in the absence of wall recombination have measured the dependence of the apparent two-body rate constants for the 0 + NO + M system on the partial pressure of the third body, and estimated the two-body radiative reaction rate-constants over the 10-l Pa pressure range. In the crossed beam chemihuninescence study for the 0 + dimerized NO system, no chemiluminescence due to the 0 + NO elementary reaction has been observed WI
-
For the quantitative study on the chemiluminescence in the 0 + NO elementary reaction, conventional flow methods seem to be not adequate because of its inhomogeneous mixing of reagent gases and also of the complexity introduced by secondary reactions. The emission spectrum in the 0 + NO elementary reaction, however, has not been measured directly by use of the crossed beam technique so far. One of the
reasons for this may be that the reaction is strongly exothermic, and major product of 0 + NO binary collisions is likely to dissociate into 0 and NO irnmediately [ 13]_ The purpose of the present study is to observe directly such a weak emission spectrum due to the 0 + NO elementary reaction by a crossed beam technique.
2. Experimental Fig. 1 shows a cross sectional view of the reaction chamber used throughout the present study. Oxygen atoms are generated by the 2.45 GHz microwave discharge in a Broida type cavity. The power input to the magnetron oscillator was 200 W. To ensure a constant yield of oxygen atoms the anode current of the magnetron oscillator was kept constant throughout the experiment_ In order to reduce the recombination of the generated oxygen atoms, the quartz discharge tube of 15 mm i-d. is coated with teflon. The guide pipe of 12 mm i-d., nozzle (1.5 mm i-d., and 5 mm long), and aperture (2 mm i-d.) are made of teflon. Spacing between the teflon nozzle and the aperture is 4 mm [14]. The multichannel nozzle [ 151 consists of one hundred and twenty fme stainless steel tubes (0.2 mm i-d., and 5 mm long) bunched rogether and has an over-all diameter of 6 mm. Distances from the crossing point to
Volume 56, number 1
CHEMICAL
Lo_
I
: :
PHYSICS LETTERS
. \
\,, ,/-
15 May 1978
o-5a-n
:\ L
\
Fig. 1. Cross sectional view of the reaction chamber. the aperture and to the multichannel nozzle are 7 and 5 nun, respectively. The fore-chamber and the reaction chamber were evacuated by a 4-inch (450 dm3/s) and a 6-inch (800 dm3/s) diffusion pump, respectively. Nitric oxide was admitted into the reaction chamber through the multichannel nozzle as shown in fig_ 1 and was crossed with the oxygen beam at right angle. The angular dependence of the oxygen flux-intensity is shown in fig. 2. Avacuum gauge was rotated with the radius of 3 cm around the crossing point as shown in the figure. The peak height of each curve represents the fluxintensity, [ 16,171. For convenience, au arbitrary unit is taken for the flux-intensity regarding the velocity of oxygen beam as unity, so that the flux-intensity at the crossing point can easily be compared with the background pressure_ As the pressure at the oxygen reservoir increased from 130 to 530 Pa, the width of the beam at half intensity increased from 42 to 66 degrees as shown in fig. 2. The oxygen flux-intensity was found to be inversely proportional to the square of the distance from the nozzle. The NO flux-intensities were found to show a similar angular dependence to that of the oxygen flux and also decreased with the distance obeying the inverse square law. These results show that even in the case of the
C
Fii. 2. Angular dependence of the oxygen flux-intensity. The angle 6 is defined at the top in the fiure. The diameter of the inlet section of the ionization vacuum gauge is 2.5 nun, corresponding to an angular resolution of 5”. The pressures at the oxygen reservoir are: A, 530 Pa; B,400 Pa; C, 270 Pa; D, 130 Pa.
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Volume 56, number 1
PHYSICS LEITERS
introduction of such large amount of reagent gases into the reaction chamber, intense diverging-beams GUI be realized with the present inlet system composed of the nozzle and the aperture and also of the multichannel nozzle alone. The background pressure increased gradually from !I04 Pa to 0.2 Pa as the NO flux-intensity increased from 3 to 15 in the arbitrary unit mentioned above. The dimerization of nitric oxide due to the adiabatic expansion after the nozzle was negligible in this experiment [ 18-23]_ The emission at the crossing region was detected by an R374 photomultiplier (Hamamatsu TV Co.) through a quartz window, a light chopper, and a monochromator of Czemy-Turner type (F/3_5,f= 20 cm, 600 grooves/mm). Detected signal was amplified by a preamplifier and a lock-in amplifier, and followed by the on-line accumulation up to 1000 runs with a MELCOM 70 minicomputer (Mitsubishi Electric Co.). The chemiluminescence in the near infrared region from 0.8 to 1 w was detected by an R316 (S-l) photomultiplier (Hamamatsu TV Co.). Nitric oxide either in a glass cylinder (purity 99.9 vol. %) or in a metallic cyclinder (purity 99 vol. %), and oxygen (purity 99.5 vol. %) were used without further purification.
I
700
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I
600 500 Wovelength/nm
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15 May
3. Results and discussion Fig_ 3 shows the emission spectrum obtained in the 0 + NO reaction at flux-intensities of 11 and 3.4 (in the arbitrary unit as mentioned before) for NO and 0, respectively. The resolution of the monochromator was 20 nm, and the number of accumulations was 1000. The bottom spectrum in fig. 3 shows the background, thus the stray light from the oxygen discharge can be neglected. Species downstream from the microwave discharge of oxygen are known to be the oxygen atom solely in the ground state (3P), not in lD or ‘S, and a little amount of the excited oxygen molecule O#Ag) and ozone [24] _ The chemiluminescent reactions of these minor species with NO cannot be the source of the continuous emission spectrum which starts at a wavelength of 400 run because of smaller reaction energies they release. The dissociation limit of the ground state NO, into 0(3P) and NO(2lI) is known to be about 25000 cm-’ 125 ] , thus the structureless continuous emission spectrum obtained was assigned to that of the electronically excited NO2 formed in the 0 + NO reaction. Fig. 4 represents the dependence of the emission in-
I
300
I I
700
I
I
600 500 WaveIengrh/nm
I
400
1
0 I
NO
300
Fig. 3. Emission spectrum of NO, at flux-intensities of 11 and 3.4 for NO and oxygen, respectively. The bottom spectrum shows the background at ffux-intensities of 0.0 and 3.4 for NO and oxygen, respectively. These spectra are uncorrected for the sensitivity of the optical detection system.
86
1978
5 FIJJX-I
I
I
15 urutsl
r+4msrE (arb
Fig. 4. Dependence of the emission intensities at fixed wave lengths on the NO flux-intensity; 0, at 500 MI; 0, at 600 nm; o, at 700 MI_ The abscissa represents the total NO flux-intensity over the whole reaction region viewed by the detector. Each point denotes the averaged emission intensity over 12500
runs.
Volume 56, number 1
CHEMCIAL
PHYSICS LETTERS
tensities on the NO flwr-intensities-at fiied wavelengths of 500,600, and 700 nm, respectively. The resolution was fmed at 20 nm. A plot of the emission intensity versus the NO flux-intensity at each wavelength shows a good linear relationship. The dependence of the emission intensity on the oxygen flux was accomplished only in the range of flux-intensity between 2 and 3.5 because of the instability of the microwave discharge at iower oxygen pressures_ The emission intensity was also first order with respect to the flux-intensity of the oxygen atom if the efficiency of dissociation into the oxygen atoms in the discharge region -wasassumed to be constant within such a variation of the flux-intensity. The linear dependence of the intensity of cherniluminescence on both the NO and 0 flux-intensities shows that the emission observed under the present experimental conditions is to be ascribed to the single collision of a NO molecule with an oxygen atom. For the chemically excited NO,, 2A2, 4Az, and 4B2 are energetically accessible excired states in addition to 2B1 and 2B2 [26] _ Based on the analyses of the absorption and fluorescence spectra of NO,, it is suggested that ‘&e 2B2 -*A, transition is very important in the visible and near infrared region [2732] _The lifetime of 2B2 is known to be short [3335] _ More recently, the studies of a laser induced fluorescence excitation spectrum at low rotational temperature [36] and the studies of NO, fluorescence lifetime [35] suggest that the 2B2 state is strongly perturbed by vibrationally excited ground state 2A1 _ In view of these, the 2B2 (or the perturbed 2B2) state may be responsible for the emission of the chemically excited NO,, because the emission from shorter-lived states must be dominant in the crossing region viewed by the detector. The result that the emission intensities at the three different wavelengths depend linearly on the NO fluxintensity suggests that intermolecular collisional processes in the emission process are reduced by the diverging-beam technique. Thus the chemiluminescent spectrum of NO, obtained under the present experimental conditions may reflect the internal state population free from the collisional perturbation with a third body.
15 May 1978
Acknowledgement The authors are indebted to professor M. Date for allowing thrm to use a MELCOM minicomputer system.
References [l] F. Kaufman, Proc. Roy. Sec. A247 (19S8) 123. [2] A. Fontijn, C-B. Meyer and H.L Schiff. J. Chem. Phys.
40 (1964) 64. [3] N. Jonathan and R. Petty, Trans. Faraday Sot_ 64 (1968) 1240. [4] H.P. Broida, H-1. Schiff and T-hi. Sugden,Trans. Faraday Sot. 57 (1961) 259. [S] R.R. Reeves, P. Harteckand W-H. Chase, I. Chem. Phys. 41 (1964) 764. [6] D.B. Hartley and B.A. Thrush, Froc. Roy. Sot. A297 (1967) 520. [7] M.A.A. Clyne and B.A. Thrush, Proc. Roy. Sot. A269 (1962) 404. [8] B.A. Thrush, Ann. Rev. Phys. Chem. 19 (1968) 371. [9] F. Kaufman, Ann. Rev. Phys. Chem. 20 (1969) 45. [lo] M.A.A. Clyne, Physical chemistry of fast reactions, Vol. 1 (Plenum Press, New York, 1973). p. 245. [ll ] K-H. Becker, W. Groth and D. Thran, Chem. Phys. Letters 15 (1972) 215. [12] T. Ibaraki, K. Kodera and I. Kusunoki, _I.Phys. Chem.
79 (1975) 95. [ 131 G. Her&berg, Molecular spectra and molecular structure,
Vol. 3 (Van Nostrand, Princeton, 1966) p. 473. [14] J.P. VaUeau and J-M. Deckers, Can. J. Chem. 42 (1964) 22s. [lS] J.A. Giordmaine and T-C. Wang, J. Appl. Phys. 31 (1960) 463s 1161 J. Deckers and J-B. Fenn, Rev. Sci. Instr. 34 (1963) 96. [17] W.H. Rodebush, Rev. Mod. Phys. 3 (1931) 392. [18] E A. Guggenheim, Mol. Phys. 10 (1966) 401. [19] R-L. Scott, Mol. Phys. 11 (1966) 399. 1201 E.A. Guggenheim, Mol. Phys. 11 (1966) 403. [21] A. Fontijn aad D.E. Rosner, J. Chem. Phys. 46 (1967) 3275. [22] D. Golomb and R.E. Good, J. Chem. Phys. 49 (1968) 4176. 123) F-T. Greene and T.A. Milne, J. Chem. Phys. 39 (1963) 3150. [24] Y. Takezaki and S. Mori. reported at the International Conference on Photochemistry 1967, Mtichen, and at the Second Symposium on Fast Reactions, 1967, Kyoto, Japan. [2S] A.E. Douglas and K-P Huber, Can. J. Phys. 43 (1965) 1261 Eb.
Paulsen, W-F. Sheridan and R.E. Huffman, J. Chem.
Phys. 53 (1970) 647. 87
Volume 56, number 1
CHEMICAL PHYSICS LETTERS
1271 K. Sakurai and H.P. Broida, J. Chem. Phys. 50 (1969) 2404. [28: K. Abe, F. Myers, T.K. McCubbin and S-R. Polo. J. Mol. Spectry. 38 (1971) 552. [29] J.C.D. Brand, J-L. Harduiick, R.J. Pirkle and CJ. Seliskar, Can. J. Pbys. 51 (1973) 2184. [30] K. Abe, J. Mol. Spectry. 48 (1973) 395. (311 T. Tanaka, K. Abe and R-F. Cuzl, J. Mol. Spectry. 49 (1974) 310. 132) K_ Abe, F. Myers, T.K. McCubbin Jr. and S.R. Polo, I. Mol. Spectry. 50 (1974) 413.
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15 May 1978
[33] D. Neubergex and A.B.F. Duncan, J_ Chem. PXzys_22 (1954) 1693. [34] C.G. Stevens, M.W. !&agel, R. WalIace and R.N. Zue, Chem. Phys. Letters 18 (1973) 465. _ [3.51 V.M. Donnelly and F. Kaufman, J. Chem.Phys. 66 (1977) 4100. 1361 R.E. Smalley, L. Wharton and D.H. Levy, J. Chem. Phys. 63 (1975) 4977.
CHEMICAL PHYSICS LE-ITERS
Volume 56, number 1
STUDY OF CHEMILUMINESCENCE
IN 0 -I-NO ELEMENTARY
REACI’ION
BY A CROSSED BEAM TECHNIQUE Toshio MASAI, TSURIO~UMASUI, Hideaki NAKANE, ichiro HANAZAKi and Keiji KUWATA Department of Chemistry, Faculty of Science, Osahz UniveWty. Toyonaka, Osaka 560. Japan Received 15 February
1978
Chemihnninescent spectra of nitrogen dioxide in the visiile region have been observed in the 0 f NO elementary reaction by a crossed beam technique_ Dependences of the emission intensity on both the nitric oxide and atomic oxygen fluxintensities were fti order, and the emission was concentrated near the crossing point. These results show that the cherniluminescence observed is due to the chemically excited NOa formed in the binary reaction between NO and 0.
1. Introduction The chemihuninescent reaction of nitric oxide with atomic oxygen has been of much interest because of its major role in stratospheric reactions and of its importance as a standard in the determination of emission rates. There have been extensive investigations and numerous pioneering works in this reaction system [l-9]. The emission due to the 0 + NO binary reaction at low pressures has been observed mainly by discharge flow methods [lOI _ Becker et al. [ll] , in the absence of wall recombination have measured the dependence of the apparent two-body rate constants for the 0 + NO + M system on the partial pressure of the third body, and estimated the two-body radiative reaction rate-constants over the 10-l Pa pressure range. In the crossed beam chemihuninescence study for the 0 + dimerized NO system, no chemiluminescence due to the 0 + NO elementary reaction has been observed WI
-
For the quantitative study on the chemiluminescence in the 0 + NO elementary reaction, conventional flow methods seem to be not adequate because of its inhomogeneous mixing of reagent gases and also of the complexity introduced by secondary reactions. The emission spectrum in the 0 + NO elementary reaction, however, has not been measured directly by use of the crossed beam technique so far. One of the
reasons for this may be that the reaction is strongly exothermic, and major product of 0 + NO binary collisions is likely to dissociate into 0 and NO irnmediately [ 13]_ The purpose of the present study is to observe directly such a weak emission spectrum due to the 0 + NO elementary reaction by a crossed beam technique.
2. Experimental Fig. 1 shows a cross sectional view of the reaction chamber used throughout the present study. Oxygen atoms are generated by the 2.45 GHz microwave discharge in a Broida type cavity. The power input to the magnetron oscillator was 200 W. To ensure a constant yield of oxygen atoms the anode current of the magnetron oscillator was kept constant throughout the experiment_ In order to reduce the recombination of the generated oxygen atoms, the quartz discharge tube of 15 mm i-d. is coated with teflon. The guide pipe of 12 mm i-d., nozzle (1.5 mm i-d., and 5 mm long), and aperture (2 mm i-d.) are made of teflon. Spacing between the teflon nozzle and the aperture is 4 mm [14]. The multichannel nozzle [ 151 consists of one hundred and twenty fme stainless steel tubes (0.2 mm i-d., and 5 mm long) bunched rogether and has an over-all diameter of 6 mm. Distances from the crossing point to
Volume 56, number 1
CHEMICAL
Lo_
I
: :
PHYSICS LETTERS
. \
\,, ,/-
15 May 1978
o-5a-n
:\ L
\
Fig. 1. Cross sectional view of the reaction chamber. the aperture and to the multichannel nozzle are 7 and 5 nun, respectively. The fore-chamber and the reaction chamber were evacuated by a 4-inch (450 dm3/s) and a 6-inch (800 dm3/s) diffusion pump, respectively. Nitric oxide was admitted into the reaction chamber through the multichannel nozzle as shown in fig_ 1 and was crossed with the oxygen beam at right angle. The angular dependence of the oxygen flux-intensity is shown in fig. 2. Avacuum gauge was rotated with the radius of 3 cm around the crossing point as shown in the figure. The peak height of each curve represents the fluxintensity, [ 16,171. For convenience, au arbitrary unit is taken for the flux-intensity regarding the velocity of oxygen beam as unity, so that the flux-intensity at the crossing point can easily be compared with the background pressure_ As the pressure at the oxygen reservoir increased from 130 to 530 Pa, the width of the beam at half intensity increased from 42 to 66 degrees as shown in fig. 2. The oxygen flux-intensity was found to be inversely proportional to the square of the distance from the nozzle. The NO flux-intensities were found to show a similar angular dependence to that of the oxygen flux and also decreased with the distance obeying the inverse square law. These results show that even in the case of the
C
Fii. 2. Angular dependence of the oxygen flux-intensity. The angle 6 is defined at the top in the fiure. The diameter of the inlet section of the ionization vacuum gauge is 2.5 nun, corresponding to an angular resolution of 5”. The pressures at the oxygen reservoir are: A, 530 Pa; B,400 Pa; C, 270 Pa; D, 130 Pa.
85
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Volume 56, number 1
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introduction of such large amount of reagent gases into the reaction chamber, intense diverging-beams GUI be realized with the present inlet system composed of the nozzle and the aperture and also of the multichannel nozzle alone. The background pressure increased gradually from !I04 Pa to 0.2 Pa as the NO flux-intensity increased from 3 to 15 in the arbitrary unit mentioned above. The dimerization of nitric oxide due to the adiabatic expansion after the nozzle was negligible in this experiment [ 18-23]_ The emission at the crossing region was detected by an R374 photomultiplier (Hamamatsu TV Co.) through a quartz window, a light chopper, and a monochromator of Czemy-Turner type (F/3_5,f= 20 cm, 600 grooves/mm). Detected signal was amplified by a preamplifier and a lock-in amplifier, and followed by the on-line accumulation up to 1000 runs with a MELCOM 70 minicomputer (Mitsubishi Electric Co.). The chemiluminescence in the near infrared region from 0.8 to 1 w was detected by an R316 (S-l) photomultiplier (Hamamatsu TV Co.). Nitric oxide either in a glass cylinder (purity 99.9 vol. %) or in a metallic cyclinder (purity 99 vol. %), and oxygen (purity 99.5 vol. %) were used without further purification.
I
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600 500 Wovelength/nm
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15 May
3. Results and discussion Fig_ 3 shows the emission spectrum obtained in the 0 + NO reaction at flux-intensities of 11 and 3.4 (in the arbitrary unit as mentioned before) for NO and 0, respectively. The resolution of the monochromator was 20 nm, and the number of accumulations was 1000. The bottom spectrum in fig. 3 shows the background, thus the stray light from the oxygen discharge can be neglected. Species downstream from the microwave discharge of oxygen are known to be the oxygen atom solely in the ground state (3P), not in lD or ‘S, and a little amount of the excited oxygen molecule O#Ag) and ozone [24] _ The chemiluminescent reactions of these minor species with NO cannot be the source of the continuous emission spectrum which starts at a wavelength of 400 run because of smaller reaction energies they release. The dissociation limit of the ground state NO, into 0(3P) and NO(2lI) is known to be about 25000 cm-’ 125 ] , thus the structureless continuous emission spectrum obtained was assigned to that of the electronically excited NO2 formed in the 0 + NO reaction. Fig. 4 represents the dependence of the emission in-
I
300
I I
700
I
I
600 500 WaveIengrh/nm
I
400
1
0 I
NO
300
Fig. 3. Emission spectrum of NO, at flux-intensities of 11 and 3.4 for NO and oxygen, respectively. The bottom spectrum shows the background at ffux-intensities of 0.0 and 3.4 for NO and oxygen, respectively. These spectra are uncorrected for the sensitivity of the optical detection system.
86
1978
5 FIJJX-I
I
I
15 urutsl
r+4msrE (arb
Fig. 4. Dependence of the emission intensities at fixed wave lengths on the NO flux-intensity; 0, at 500 MI; 0, at 600 nm; o, at 700 MI_ The abscissa represents the total NO flux-intensity over the whole reaction region viewed by the detector. Each point denotes the averaged emission intensity over 12500
runs.
Volume 56, number 1
CHEMCIAL
PHYSICS LETTERS
tensities on the NO flwr-intensities-at fiied wavelengths of 500,600, and 700 nm, respectively. The resolution was fmed at 20 nm. A plot of the emission intensity versus the NO flux-intensity at each wavelength shows a good linear relationship. The dependence of the emission intensity on the oxygen flux was accomplished only in the range of flux-intensity between 2 and 3.5 because of the instability of the microwave discharge at iower oxygen pressures_ The emission intensity was also first order with respect to the flux-intensity of the oxygen atom if the efficiency of dissociation into the oxygen atoms in the discharge region -wasassumed to be constant within such a variation of the flux-intensity. The linear dependence of the intensity of cherniluminescence on both the NO and 0 flux-intensities shows that the emission observed under the present experimental conditions is to be ascribed to the single collision of a NO molecule with an oxygen atom. For the chemically excited NO,, 2A2, 4Az, and 4B2 are energetically accessible excired states in addition to 2B1 and 2B2 [26] _ Based on the analyses of the absorption and fluorescence spectra of NO,, it is suggested that ‘&e 2B2 -*A, transition is very important in the visible and near infrared region [2732] _The lifetime of 2B2 is known to be short [3335] _ More recently, the studies of a laser induced fluorescence excitation spectrum at low rotational temperature [36] and the studies of NO, fluorescence lifetime [35] suggest that the 2B2 state is strongly perturbed by vibrationally excited ground state 2A1 _ In view of these, the 2B2 (or the perturbed 2B2) state may be responsible for the emission of the chemically excited NO,, because the emission from shorter-lived states must be dominant in the crossing region viewed by the detector. The result that the emission intensities at the three different wavelengths depend linearly on the NO fluxintensity suggests that intermolecular collisional processes in the emission process are reduced by the diverging-beam technique. Thus the chemiluminescent spectrum of NO, obtained under the present experimental conditions may reflect the internal state population free from the collisional perturbation with a third body.
15 May 1978
Acknowledgement The authors are indebted to professor M. Date for allowing thrm to use a MELCOM minicomputer system.
References [l] F. Kaufman, Proc. Roy. Sec. A247 (19S8) 123. [2] A. Fontijn, C-B. Meyer and H.L Schiff. J. Chem. Phys.
40 (1964) 64. [3] N. Jonathan and R. Petty, Trans. Faraday Sot_ 64 (1968) 1240. [4] H.P. Broida, H-1. Schiff and T-hi. Sugden,Trans. Faraday Sot. 57 (1961) 259. [S] R.R. Reeves, P. Harteckand W-H. Chase, I. Chem. Phys. 41 (1964) 764. [6] D.B. Hartley and B.A. Thrush, Froc. Roy. Sot. A297 (1967) 520. [7] M.A.A. Clyne and B.A. Thrush, Proc. Roy. Sot. A269 (1962) 404. [8] B.A. Thrush, Ann. Rev. Phys. Chem. 19 (1968) 371. [9] F. Kaufman, Ann. Rev. Phys. Chem. 20 (1969) 45. [lo] M.A.A. Clyne, Physical chemistry of fast reactions, Vol. 1 (Plenum Press, New York, 1973). p. 245. [ll ] K-H. Becker, W. Groth and D. Thran, Chem. Phys. Letters 15 (1972) 215. [12] T. Ibaraki, K. Kodera and I. Kusunoki, _I.Phys. Chem.
79 (1975) 95. [ 131 G. Her&berg, Molecular spectra and molecular structure,
Vol. 3 (Van Nostrand, Princeton, 1966) p. 473. [14] J.P. VaUeau and J-M. Deckers, Can. J. Chem. 42 (1964) 22s. [lS] J.A. Giordmaine and T-C. Wang, J. Appl. Phys. 31 (1960) 463s 1161 J. Deckers and J-B. Fenn, Rev. Sci. Instr. 34 (1963) 96. [17] W.H. Rodebush, Rev. Mod. Phys. 3 (1931) 392. [18] E A. Guggenheim, Mol. Phys. 10 (1966) 401. [19] R-L. Scott, Mol. Phys. 11 (1966) 399. 1201 E.A. Guggenheim, Mol. Phys. 11 (1966) 403. [21] A. Fontijn aad D.E. Rosner, J. Chem. Phys. 46 (1967) 3275. [22] D. Golomb and R.E. Good, J. Chem. Phys. 49 (1968) 4176. 123) F-T. Greene and T.A. Milne, J. Chem. Phys. 39 (1963) 3150. [24] Y. Takezaki and S. Mori. reported at the International Conference on Photochemistry 1967, Mtichen, and at the Second Symposium on Fast Reactions, 1967, Kyoto, Japan. [2S] A.E. Douglas and K-P Huber, Can. J. Phys. 43 (1965) 1261 Eb.
Paulsen, W-F. Sheridan and R.E. Huffman, J. Chem.
Phys. 53 (1970) 647. 87
Volume 56, number 1
CHEMICAL PHYSICS LETTERS
1271 K. Sakurai and H.P. Broida, J. Chem. Phys. 50 (1969) 2404. [28: K. Abe, F. Myers, T.K. McCubbin and S-R. Polo. J. Mol. Spectry. 38 (1971) 552. [29] J.C.D. Brand, J-L. Harduiick, R.J. Pirkle and CJ. Seliskar, Can. J. Pbys. 51 (1973) 2184. [30] K. Abe, J. Mol. Spectry. 48 (1973) 395. (311 T. Tanaka, K. Abe and R-F. Cuzl, J. Mol. Spectry. 49 (1974) 310. 132) K_ Abe, F. Myers, T.K. McCubbin Jr. and S.R. Polo, I. Mol. Spectry. 50 (1974) 413.
88
15 May 1978
[33] D. Neubergex and A.B.F. Duncan, J_ Chem. PXzys_22 (1954) 1693. [34] C.G. Stevens, M.W. !&agel, R. WalIace and R.N. Zue, Chem. Phys. Letters 18 (1973) 465. _ [3.51 V.M. Donnelly and F. Kaufman, J. Chem.Phys. 66 (1977) 4100. 1361 R.E. Smalley, L. Wharton and D.H. Levy, J. Chem. Phys. 63 (1975) 4977.