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A comparison of nuclear charge distribution in thermal-neutron induced fission of 233U and 235U
J. inorg, nucl. Chem., 197 I, Vol. 33, pp, 4327-4333.
Pergamon Press.
Printed in Great Britain
NOTES A comparison of nuclear charge distribution in thermal-neutron induced fission of 233U and 235U (Received 8 March 1971 ) FRACTIONAL independent yields of several products of thermal-neutron induced fission of 233U have been reported recently from this laboratory[l-4]. The fractional independent yield, FlY, can be defined by the equation
F l Y = Y(,4, Z) Y(,4 )
(I)
where Y (A, Z) is the independent yield of the product AZ and Y (,4) is the total or cumulative yield of all products with mass number,4. In like manner, fractional cumulative yields, FCY, are defined as F C Y - 7"zY ('4'
}'(`4)
Z).
(2)
From a knowledge of values of fractional independent and cumulative yields it is possible to gain an understanding of the nuclear charge distribution which occurs during the fission process. The purpose of this paper is to compare radiochemical measurements of nuclear charge distribution in thermalneutron induced fission of 233U to those for fission ofz35U. Empirical treatments describing charge distribution for zasu fission, based on radiochemical data, have recently been proposed by Mukherji[5] and by Wahl et al.[6]. Mukherji finds that the most probable charge, Zp, for a fission product of mass A, is given by
,4;, (Zp)u
2.587--+0.005.
{3)
The subscript H indicates a fragment from the heavy peak. The prescription is also used for yields of light fragments if (Zo)~j and A~, are converted to their complements. He further concludes that for all cases of thermal-neutron induced and spontaneous fission the most probable neutron to proton (and therefore, ,4'H/(Zp),) ratio remains constant. Wahl et a/.[6] find that (Zp) . = [A'H(Z F I A F ) -- (0"45 --+O' I0)1
(4)
where Zp and "4F are Z and ,4 for the fissioning nucleus. Again a similar relation exists for light fragments, but for which the constant is + (0-45__+0-10). They also find the distribution to be approximately Gaussian with a standard deviation, tr, of (0.56___0.06). An equation similar to that of Wahl et a/.[6] has been derived by Armbruster [7] from theoretical considerations. L. H. Niece, D. E. Troutner and R. L. Ferguson, Phys. Rev. 1C, 312 (1970). N . G . Runnalls and D. E. Troutner, Phys. Rev. 1C, 316 (1970). M. Eichor and D. E. Troutner, J. inorg, nucl. Chem. 33, 1543 ( 1971). L. Berge, Private communication of preliminary results. S. Mukherji, Nucl. Phys. 129A, 297 (1969). A. C. Wahl, A. E. Norris, R. A. Rouse, and J. C. Williams, Proc. 2nd Symp. Phys. Chem. o f Fission, Vienna, Austria, 1969 p. 813. I AEA, Vienna, Austria (1969). 7. P. Armbruster. Nucl. Phys. 140A, 385 (1970). 4327
I. 2. 3. 4. 5. 6.
4328
Notes
These two equations are in excellent agreement for 2ssU fission. When the prescription of Wahl et a/.[6] is used to compute a value for the constant shown in Mukherji's[5] relation the results are 2.589 and 2.585 for A n -- 130 and 146 respectively. These values were chosen since they essentially bracket the heavy mass region for which significant amounts of charge distribution data are available. It is obvious, however, that this agreement cannot extend to 23aU fission. From Mukherji's[5] prescription, for which (Zp)n is not a function of the charge and mass of the fissioning nucleus, a charge distribution equivalent to that for 2asU fission would be predicted for the heavy products from 233U fission. On the other hand, (Zp)n is a function of those parameters in the prescription of Wahl et a/.[6] and from it a significantly different value of (Zp)n for a given A' would be predicted. DATA Data are shown in Tables 1-4. All yields are presented as fractional cumulative yields. Only nuclides for which the fractional cumulative yield falls between 0.01 and 0.99 for at least one of the fission processes have been considered. Yields for 2asU are all from Wahl et a/.[6]. Yields for ~aaU are taken from several sources. Fractional cumulative yields of ~sY[1], ~31Te[4], 132Te[2], 139Cs[3], and ~4°Cs[3] are from this laboratory. The yield of ~aSTe is taken from Qaim and Denschlag[8] and the values for ~3aTe and 134Te are averages of the results of those workers and ones from this laboratory [2]. The yield of ~aSl is from Okazaki et a/.[9]. Yields for ~aeXe and 97Zr are from an earlier work by Wahl et a/.[10]. The fractional cumulative yields of the other Xe isotopes and of the Kr isotopes are from Wolfsberg[11]. Values of A' have been estimated to the nearest 0.1 mass units from the neutron emission results of Apalin et al.[ 12]. Table 1. Fractional cumulative yields of heavy products from fission of usU
An
Zn
A 'H
AH(ZFM~)
131 132 133 134 135 135 136 137 138 139 139
52 52 52 52 52 53 54 54 54 54 55
131.4 132.5 133.7 134.8 135.9 135.9 137.0 138.1 139.2 140.3 140.3
51.22 51.65 52.12 52.55 52.98 52.98 53.41 53.84 54.26 54.69 54.69
140 140 141
54 55 54
141"4 141"4 142"5
55"12 55"12 55'55
142
54
143"6
55"98
Fractional cumulative yield* 0.9986___0.0002 0.9961 _+0.0003 0.975_+0.003 0.89--.0-01 0.50---0-04 0.96___0.01 0.99907 -+ 0.00005 0.978___0.003 0.953 - 0.002 0.82-+0.02 0.989+0.003 0.005 0.596-- 0.001 0.954-----0'030 0"205 + 0"019 --0.004 0.059 + 0-008 -- 0-003 -
*Ref.[6]. 8. S. M. Qaim and H. O. Denschlag, J. inorg, nucl. Chem. 32, 1767 (1970). 9. A. Okazaki, W. H. Walter and C. B. Bigham, Can.J. Phys. 44, 237 (1966). 10. A. C. Wahl, R. L. Ferguson, D. N. Nethaway, D. E. Troutner and K. Wolfsberg, Phys. Rev. 126, 1112 (1962). 11. K. Wolfsberg, Phys. Rev. 137, B929 (1965). 12. V. F. Apalin, Y. N. Gritsyuk, 1. E. Kutikov, V. I. Lebedev and L. A. Mikaelian, Nucl. Phys. 71,553 (1965).
Notes
4329
Table 2. Fractional cumulative yields of heavy products from fission of 233U
An
Zn
A'n
131 132 133 134 135 135 136 137 138 139 139 140 140 141 142
52 52 52 52 52 53 54 54 54 54 55 54 55 54 54
131.5 132.6 133.8 134-9 136.0 136-0 137.1 138.2 139.3 140"4 140"4 141 "5 141 "5 142"6 143"7
A'H(Zv/Ap)
Fractional cumulative yield
51.70 52-13 52.60 53.04 53.47 53.47 53-90 54.33 54.77 55'20 55"20 55"63 55"63 56"06 56"50
0.980±0-002* 0.94± 0.03t 0.83 ±0.04t 0.62±0.035 0.20±0-02§ 0.805 ± 0.00@I 0-986±0-004¶ 0.896±0.005** 0.827±0.012"* 0"476±0'008** 0"916±0"00777 0"225 ± 0"006* * 0"73 ± 0"04t + 0-051 ±0"003** 0'0098+0"8** --0"5
~:Ref.[4]. tRef.[2]. SAverage from Refs.[2 and 8]. § Ref.[8]. HRef.[9]. ¶Ref.[10]. ~*Ref.[11]. t t Ref.[3].
Table 3. Fractional cumulative yields of light products from fission of 235U shown as yields of complements
¢
r
AL
A'L
ZL
Zn
AH
An(Zr/AF)
89 90 91 92 93
90-0 91.1 92.1 93.2 94.2
36 36 36 36 36
55 55 55 55 55
146.0 144-9 143-9 142.8 141-8
56-92 56.49 56-10 55.67 55.28
95 97
96.3 98-4
39 40
52 51
139.7 137-6
54.46 53.64
Heavy product fractional cumulative yield* 0-040 ± 0.004 0.14-----0.02 0.41 ±0.01 0.69±0.01 0.922+0.002 --0.012 0-004 ± 0-002 0.0017±0.0008
* Yields have been calculated from cumulative yields of light-mass nuclides given in Ref.[6].
4330
Notes Table 4. Fractional cumulative yields of light products from fission of 233U shown as yields of complements
AL
A'~
ZL
z,,
A'~
A'.(Zr/A~)
89 90 91 92 93 95 97
90.0 91"1 92"1 93'2 94.2 96'3 98'4
36 36 36 36 36 39 40
55 55 55 55 55 52 51
144-0 142'9 141.8 140.8 139'8 137.7 135'6
56.61 56.18 55.79 55.36 54.96 54-14 53'31
Heavy product fractional cumulative yield* 0"139--±0"005t 0"335 ±0"012? 0-67±0'01t 0'873 ± 0'005T 0"977 +--0'00It 0'034 ± 0"009~: 0"011 ±0"004§
* Yields have been calculated from yields of light-mass nuclides given in references shown. ?Ref.[1 1]. ~Ref.[1]. § Ref.[10]. DISCUSSION If it is assumed that nuclear charge distribution for a given mass chain is Gaussian, the fractional cumulative yield of element Z is represented by 1
f(Z+l/2)
o- (2~r) ' J _ ~
(5)
A plot of F C Y as a function of Z on probability paper results in a straight line with a slope related to oand which crosses a probability of 0.5 at Z = ( Z p - 0 " 5 ) . Yields from several different chains can be compared if they are plotted as a function of Z - Z p . In the Wahl et a/.[6] treatment this is equivalent to plotting yields of heavy fragments as a function of { Z n - [A'H(ZF/AF)] + 0"45}. Since the value 0.45 is taken to be a constant, a straight line should also result if yields are plotted as a function of {ZH -- [A'n(ZHAF)]} with the line crossing a probability of 0.5 at {ZH- [A~(ZF/AF)]} = --0"95. Yields for light fragments can be plotted on the same graph if they are represented as yields of the complementary heavy fragments following the method used by Mukherji [5]. Figure 1 is such a plot for 235U fission. The line is drawn to represent (Zp)u = [A'n (Z~/At,) -- 0.45] and o- = 0.56. Note that there is general agreement between the points and the line, but that many points deviate from the line. This may be due to odd-even effects [6], shell effects [6], or deviations of cr from the average value of 0.56. Figure 2 is a similar plot for yields from 2~3U. Again, there is a general agreement with the line, indicating that similar charge distributions apply for 23aU and z35U fission. Furthermore, except for the difference in A'(Z.~,]AF) for the two processes, the pattern of distribution about the line is very similar for both processes. In order to point out more clearly the relation between yields from the two fission processes, a procedure has been adopted to compare yields of specific nuclides from 233U to those from 2asU. Consider, for example the point for 139Xe in Fig. 1. It falls - 0 . 2 5 charge units to the left of the line and therefore must be moved 0.25 units to the right in order to make it consistent with the line. If the point for 139Xe in Fig. 2 is moved the same number of charge units to the right it then also falls very near the line. This same comparison procedure was followed for all the yields from 2aaU and the results shown in Fig. 3. The agreement of the points with the line is now excellent, leading to the conclusion that the nuclear structure effects which lead to deviations of yields from the average charge distribution in 235U fission also exist in 2saU fission and indeed to approximately the same extent. This agreement does not mean, of course, that charge distribution for 2ssU fission is exactly that predicted by the use of the Wahl et a/.[6] prescription, but it does imply that the prescription may
Notes
433
-
~5~.
2
•
~..
I m
0
I
I
I
~
~.
o
d
pie!/~
gA! ~.Dlnu,Jno
d
~ d
ouo!¢oo~
8 o d
>,
o o o d
0 --C >, ,O
o
LL
--
T ,~ ,=, ~ . ~ - ~ I...
.o_ ~ .E I o~ d
<=.=~
I ~
~
<5
ple!,~
o~ eAN. DInLuno
o IDUO!,I.OD.J_-I
~
o
.;~ d
o 0
-~
c.
.~o
4332
Notes
0.9999 0.999-0,99 -
/
-
._~ ~
u
o L. U.
0.9--
0.5--
0.1
/
•
--
0.01/ ~ 0.001 O.O001__3L
-2i
-II 0] [z,,-A,;(z~/A~)]
Ii
Fig. 3. A plot of fractional cumulative yields of products of saaU fission as a function of [ZH-A'x(Z~M~) ] on a probability scale. Closed points are for heavy products. Open points are for complements of light products. Points have been normalized to those for 235U as described in text.
represent charge distribution for that fission process equally as well as for 2asU fission. This is in agreement with the results of the direct X-ray measurements of Glendenin et a/.[13] who find that [ ( Z p ) n - A ' ( Z ~ M F ) ] is essentially the same for fission of both 2s3U and 2~U. it is also consistent with the conclusion of Armbruster[7] that [(Zp)n--A' (ZpMF)] should be -0.45 for all asymmetric fissioning nuclei. The comparison made here does not confirm that conclusion, of course, since only two fissioning nuclei are considered. Indeed, a similar comparison for a few yields from ~szCf spontaneous fission to the same yields from 235U fission [ 14] suggests that [ (Zp) n --A' (ZF/AF)] is not the same for those two fission processes. The comparison does offer conclusive evidence, however, that (Zp)n for several different fission processes cannot be characterized by a constant A'n/Z p ratio as proposed by Mukherji [5]. When his prescription is converted to the form used by Wahl et a/.[6] [ ( Z p ) n - A ' (ZF/,'Ir)] is --0"86 and -0"99 for An = 130 and 146, respectively, for 2aaU fission. These are clearly not in agreement with --0.45. A part of the difference may be due to errors in estimating values of A'. These values would have to be in error by more than one neutron, however, to account for the large difference between -0-45 and --0.86 or -0.99. Since charge distribution for fission of two isotopes of the same element cannot be characterized by a constant An/Zp ratio, it seems doubtful that the conclusion can be drawn that it is constant for all thermal-neutron induced and spontaneous fission processes.
13. L. E. Glendenin, H. C. Griffin, W. Reisdorf and J. P. Unik, Proc. 2nd Symp. Chem. Fission, Vienna, Austria, 1969 p. 781. IAEA, Vienna, Austria (1969). 14. D. E. Troutner and N. G. Runnalls, J. inorg, nucl. Chem. 33, 2271 (1971).
Notes
4333
Acknowledgements-1 wish to thank Dr. Nelva G. Runnalls and Dr. Robert M. Harbour for their advice and criticism during the preparation of this paper and Mr. Loren Berge for permission to use his unpublished preliminary results for 131Te.
D. E. T R O U T N E R
Department o f Chemisto' University o f Missouri Columbia, Missouri 65201 U.S.A.
,I. inorg,nucl.Chem, 1971,Vol.33. pp. 4333-4339. PergamonPress. Printedin Great Britain
Studies on some metal complexes with imides as iigands (Received 10 September 1970)
THE METAL imide complexes have been studied by several workers in relation to their preparation, chemical analysis and magnetic properties[I-7]. A number of problems related to the chemistry of these compounds, however, remain uninvestigated. In this communication we report the composition, stability and structure of some metal imides obtained from the following unidentate (1, I1 and II1) and bidentate ligands (IV and V).
~,~ICO,.,,,N H
O H2C--C\ H,C NH
H2~_C O. N H
HC-C"
/
O
I Phthalimide
II Succinimide
~O'~] ~"~CON
CONHSO2 O C H :
~
HSO2 ~ C H a
IV Pyrid-2-yl-Carboxomide N-p-Toluene sulphonyl
1. 2. 3. 4. 5.
II! Glutarimide
V Benzofur-2-y/-Carboxomide N-p-Toluene sulphonyl
Mary M. Rising, Francis M. Parker and Dorothy R. Gaston, J. A m. chem. Soc. 56, 1178 (1934). E. M. Preis and W. P. Peskov, J. phys. Chem. USSR 3, 43 (1932). W.J. Pope, Br. pet. 328,506 (1929). M. V. Suba Rao and T. R. Seshadri, Proc. Ind.Acad. 1, 10A (1939). Cambi, L. Kanonica Lingi and Ruggero, Deleone Atti., Accad. Nazi. Lincei, Rend. Classi. Sci Fis. Mat. Enat. 18, 467 (1955). 6. H. V. Malnistadt and D. A. Vassallo, Analyt. Chem. 31,462 (1959). 7. Franco Gaslini and Lucio, Z-Nahum,Analyt. Chem. 31,989 (1959).
Pergamon Press.
Printed in Great Britain
NOTES A comparison of nuclear charge distribution in thermal-neutron induced fission of 233U and 235U (Received 8 March 1971 ) FRACTIONAL independent yields of several products of thermal-neutron induced fission of 233U have been reported recently from this laboratory[l-4]. The fractional independent yield, FlY, can be defined by the equation
F l Y = Y(,4, Z) Y(,4 )
(I)
where Y (A, Z) is the independent yield of the product AZ and Y (,4) is the total or cumulative yield of all products with mass number,4. In like manner, fractional cumulative yields, FCY, are defined as F C Y - 7"zY ('4'
}'(`4)
Z).
(2)
From a knowledge of values of fractional independent and cumulative yields it is possible to gain an understanding of the nuclear charge distribution which occurs during the fission process. The purpose of this paper is to compare radiochemical measurements of nuclear charge distribution in thermalneutron induced fission of 233U to those for fission ofz35U. Empirical treatments describing charge distribution for zasu fission, based on radiochemical data, have recently been proposed by Mukherji[5] and by Wahl et al.[6]. Mukherji finds that the most probable charge, Zp, for a fission product of mass A, is given by
,4;, (Zp)u
2.587--+0.005.
{3)
The subscript H indicates a fragment from the heavy peak. The prescription is also used for yields of light fragments if (Zo)~j and A~, are converted to their complements. He further concludes that for all cases of thermal-neutron induced and spontaneous fission the most probable neutron to proton (and therefore, ,4'H/(Zp),) ratio remains constant. Wahl et a/.[6] find that (Zp) . = [A'H(Z F I A F ) -- (0"45 --+O' I0)1
(4)
where Zp and "4F are Z and ,4 for the fissioning nucleus. Again a similar relation exists for light fragments, but for which the constant is + (0-45__+0-10). They also find the distribution to be approximately Gaussian with a standard deviation, tr, of (0.56___0.06). An equation similar to that of Wahl et a/.[6] has been derived by Armbruster [7] from theoretical considerations. L. H. Niece, D. E. Troutner and R. L. Ferguson, Phys. Rev. 1C, 312 (1970). N . G . Runnalls and D. E. Troutner, Phys. Rev. 1C, 316 (1970). M. Eichor and D. E. Troutner, J. inorg, nucl. Chem. 33, 1543 ( 1971). L. Berge, Private communication of preliminary results. S. Mukherji, Nucl. Phys. 129A, 297 (1969). A. C. Wahl, A. E. Norris, R. A. Rouse, and J. C. Williams, Proc. 2nd Symp. Phys. Chem. o f Fission, Vienna, Austria, 1969 p. 813. I AEA, Vienna, Austria (1969). 7. P. Armbruster. Nucl. Phys. 140A, 385 (1970). 4327
I. 2. 3. 4. 5. 6.
4328
Notes
These two equations are in excellent agreement for 2ssU fission. When the prescription of Wahl et a/.[6] is used to compute a value for the constant shown in Mukherji's[5] relation the results are 2.589 and 2.585 for A n -- 130 and 146 respectively. These values were chosen since they essentially bracket the heavy mass region for which significant amounts of charge distribution data are available. It is obvious, however, that this agreement cannot extend to 23aU fission. From Mukherji's[5] prescription, for which (Zp)n is not a function of the charge and mass of the fissioning nucleus, a charge distribution equivalent to that for 2asU fission would be predicted for the heavy products from 233U fission. On the other hand, (Zp)n is a function of those parameters in the prescription of Wahl et a/.[6] and from it a significantly different value of (Zp)n for a given A' would be predicted. DATA Data are shown in Tables 1-4. All yields are presented as fractional cumulative yields. Only nuclides for which the fractional cumulative yield falls between 0.01 and 0.99 for at least one of the fission processes have been considered. Yields for 2asU are all from Wahl et a/.[6]. Yields for ~aaU are taken from several sources. Fractional cumulative yields of ~sY[1], ~31Te[4], 132Te[2], 139Cs[3], and ~4°Cs[3] are from this laboratory. The yield of ~aSTe is taken from Qaim and Denschlag[8] and the values for ~3aTe and 134Te are averages of the results of those workers and ones from this laboratory [2]. The yield of ~aSl is from Okazaki et a/.[9]. Yields for ~aeXe and 97Zr are from an earlier work by Wahl et a/.[10]. The fractional cumulative yields of the other Xe isotopes and of the Kr isotopes are from Wolfsberg[11]. Values of A' have been estimated to the nearest 0.1 mass units from the neutron emission results of Apalin et al.[ 12]. Table 1. Fractional cumulative yields of heavy products from fission of usU
An
Zn
A 'H
AH(ZFM~)
131 132 133 134 135 135 136 137 138 139 139
52 52 52 52 52 53 54 54 54 54 55
131.4 132.5 133.7 134.8 135.9 135.9 137.0 138.1 139.2 140.3 140.3
51.22 51.65 52.12 52.55 52.98 52.98 53.41 53.84 54.26 54.69 54.69
140 140 141
54 55 54
141"4 141"4 142"5
55"12 55"12 55'55
142
54
143"6
55"98
Fractional cumulative yield* 0.9986___0.0002 0.9961 _+0.0003 0.975_+0.003 0.89--.0-01 0.50---0-04 0.96___0.01 0.99907 -+ 0.00005 0.978___0.003 0.953 - 0.002 0.82-+0.02 0.989+0.003 0.005 0.596-- 0.001 0.954-----0'030 0"205 + 0"019 --0.004 0.059 + 0-008 -- 0-003 -
*Ref.[6]. 8. S. M. Qaim and H. O. Denschlag, J. inorg, nucl. Chem. 32, 1767 (1970). 9. A. Okazaki, W. H. Walter and C. B. Bigham, Can.J. Phys. 44, 237 (1966). 10. A. C. Wahl, R. L. Ferguson, D. N. Nethaway, D. E. Troutner and K. Wolfsberg, Phys. Rev. 126, 1112 (1962). 11. K. Wolfsberg, Phys. Rev. 137, B929 (1965). 12. V. F. Apalin, Y. N. Gritsyuk, 1. E. Kutikov, V. I. Lebedev and L. A. Mikaelian, Nucl. Phys. 71,553 (1965).
Notes
4329
Table 2. Fractional cumulative yields of heavy products from fission of 233U
An
Zn
A'n
131 132 133 134 135 135 136 137 138 139 139 140 140 141 142
52 52 52 52 52 53 54 54 54 54 55 54 55 54 54
131.5 132.6 133.8 134-9 136.0 136-0 137.1 138.2 139.3 140"4 140"4 141 "5 141 "5 142"6 143"7
A'H(Zv/Ap)
Fractional cumulative yield
51.70 52-13 52.60 53.04 53.47 53.47 53-90 54.33 54.77 55'20 55"20 55"63 55"63 56"06 56"50
0.980±0-002* 0.94± 0.03t 0.83 ±0.04t 0.62±0.035 0.20±0-02§ 0.805 ± 0.00@I 0-986±0-004¶ 0.896±0.005** 0.827±0.012"* 0"476±0'008** 0"916±0"00777 0"225 ± 0"006* * 0"73 ± 0"04t + 0-051 ±0"003** 0'0098+0"8** --0"5
~:Ref.[4]. tRef.[2]. SAverage from Refs.[2 and 8]. § Ref.[8]. HRef.[9]. ¶Ref.[10]. ~*Ref.[11]. t t Ref.[3].
Table 3. Fractional cumulative yields of light products from fission of 235U shown as yields of complements
¢
r
AL
A'L
ZL
Zn
AH
An(Zr/AF)
89 90 91 92 93
90-0 91.1 92.1 93.2 94.2
36 36 36 36 36
55 55 55 55 55
146.0 144-9 143-9 142.8 141-8
56-92 56.49 56-10 55.67 55.28
95 97
96.3 98-4
39 40
52 51
139.7 137-6
54.46 53.64
Heavy product fractional cumulative yield* 0-040 ± 0.004 0.14-----0.02 0.41 ±0.01 0.69±0.01 0.922+0.002 --0.012 0-004 ± 0-002 0.0017±0.0008
* Yields have been calculated from cumulative yields of light-mass nuclides given in Ref.[6].
4330
Notes Table 4. Fractional cumulative yields of light products from fission of 233U shown as yields of complements
AL
A'~
ZL
z,,
A'~
A'.(Zr/A~)
89 90 91 92 93 95 97
90.0 91"1 92"1 93'2 94.2 96'3 98'4
36 36 36 36 36 39 40
55 55 55 55 55 52 51
144-0 142'9 141.8 140.8 139'8 137.7 135'6
56.61 56.18 55.79 55.36 54.96 54-14 53'31
Heavy product fractional cumulative yield* 0"139--±0"005t 0"335 ±0"012? 0-67±0'01t 0'873 ± 0'005T 0"977 +--0'00It 0'034 ± 0"009~: 0"011 ±0"004§
* Yields have been calculated from yields of light-mass nuclides given in references shown. ?Ref.[1 1]. ~Ref.[1]. § Ref.[10]. DISCUSSION If it is assumed that nuclear charge distribution for a given mass chain is Gaussian, the fractional cumulative yield of element Z is represented by 1
f(Z+l/2)
o- (2~r) ' J _ ~
(5)
A plot of F C Y as a function of Z on probability paper results in a straight line with a slope related to oand which crosses a probability of 0.5 at Z = ( Z p - 0 " 5 ) . Yields from several different chains can be compared if they are plotted as a function of Z - Z p . In the Wahl et a/.[6] treatment this is equivalent to plotting yields of heavy fragments as a function of { Z n - [A'H(ZF/AF)] + 0"45}. Since the value 0.45 is taken to be a constant, a straight line should also result if yields are plotted as a function of {ZH -- [A'n(ZHAF)]} with the line crossing a probability of 0.5 at {ZH- [A~(ZF/AF)]} = --0"95. Yields for light fragments can be plotted on the same graph if they are represented as yields of the complementary heavy fragments following the method used by Mukherji [5]. Figure 1 is such a plot for 235U fission. The line is drawn to represent (Zp)u = [A'n (Z~/At,) -- 0.45] and o- = 0.56. Note that there is general agreement between the points and the line, but that many points deviate from the line. This may be due to odd-even effects [6], shell effects [6], or deviations of cr from the average value of 0.56. Figure 2 is a similar plot for yields from 2~3U. Again, there is a general agreement with the line, indicating that similar charge distributions apply for 23aU and z35U fission. Furthermore, except for the difference in A'(Z.~,]AF) for the two processes, the pattern of distribution about the line is very similar for both processes. In order to point out more clearly the relation between yields from the two fission processes, a procedure has been adopted to compare yields of specific nuclides from 233U to those from 2asU. Consider, for example the point for 139Xe in Fig. 1. It falls - 0 . 2 5 charge units to the left of the line and therefore must be moved 0.25 units to the right in order to make it consistent with the line. If the point for 139Xe in Fig. 2 is moved the same number of charge units to the right it then also falls very near the line. This same comparison procedure was followed for all the yields from 2aaU and the results shown in Fig. 3. The agreement of the points with the line is now excellent, leading to the conclusion that the nuclear structure effects which lead to deviations of yields from the average charge distribution in 235U fission also exist in 2saU fission and indeed to approximately the same extent. This agreement does not mean, of course, that charge distribution for 2ssU fission is exactly that predicted by the use of the Wahl et a/.[6] prescription, but it does imply that the prescription may
Notes
433
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Notes
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Fig. 3. A plot of fractional cumulative yields of products of saaU fission as a function of [ZH-A'x(Z~M~) ] on a probability scale. Closed points are for heavy products. Open points are for complements of light products. Points have been normalized to those for 235U as described in text.
represent charge distribution for that fission process equally as well as for 2asU fission. This is in agreement with the results of the direct X-ray measurements of Glendenin et a/.[13] who find that [ ( Z p ) n - A ' ( Z ~ M F ) ] is essentially the same for fission of both 2s3U and 2~U. it is also consistent with the conclusion of Armbruster[7] that [(Zp)n--A' (ZpMF)] should be -0.45 for all asymmetric fissioning nuclei. The comparison made here does not confirm that conclusion, of course, since only two fissioning nuclei are considered. Indeed, a similar comparison for a few yields from ~szCf spontaneous fission to the same yields from 235U fission [ 14] suggests that [ (Zp) n --A' (ZF/AF)] is not the same for those two fission processes. The comparison does offer conclusive evidence, however, that (Zp)n for several different fission processes cannot be characterized by a constant A'n/Z p ratio as proposed by Mukherji [5]. When his prescription is converted to the form used by Wahl et a/.[6] [ ( Z p ) n - A ' (ZF/,'Ir)] is --0"86 and -0"99 for An = 130 and 146, respectively, for 2aaU fission. These are clearly not in agreement with --0.45. A part of the difference may be due to errors in estimating values of A'. These values would have to be in error by more than one neutron, however, to account for the large difference between -0-45 and --0.86 or -0.99. Since charge distribution for fission of two isotopes of the same element cannot be characterized by a constant An/Zp ratio, it seems doubtful that the conclusion can be drawn that it is constant for all thermal-neutron induced and spontaneous fission processes.
13. L. E. Glendenin, H. C. Griffin, W. Reisdorf and J. P. Unik, Proc. 2nd Symp. Chem. Fission, Vienna, Austria, 1969 p. 781. IAEA, Vienna, Austria (1969). 14. D. E. Troutner and N. G. Runnalls, J. inorg, nucl. Chem. 33, 2271 (1971).
Notes
4333
Acknowledgements-1 wish to thank Dr. Nelva G. Runnalls and Dr. Robert M. Harbour for their advice and criticism during the preparation of this paper and Mr. Loren Berge for permission to use his unpublished preliminary results for 131Te.
D. E. T R O U T N E R
Department o f Chemisto' University o f Missouri Columbia, Missouri 65201 U.S.A.
,I. inorg,nucl.Chem, 1971,Vol.33. pp. 4333-4339. PergamonPress. Printedin Great Britain
Studies on some metal complexes with imides as iigands (Received 10 September 1970)
THE METAL imide complexes have been studied by several workers in relation to their preparation, chemical analysis and magnetic properties[I-7]. A number of problems related to the chemistry of these compounds, however, remain uninvestigated. In this communication we report the composition, stability and structure of some metal imides obtained from the following unidentate (1, I1 and II1) and bidentate ligands (IV and V).
~,~ICO,.,,,N H
O H2C--C\ H,C NH
H2~_C O. N H
HC-C"
/
O
I Phthalimide
II Succinimide
~O'~] ~"~CON
CONHSO2 O C H :
~
HSO2 ~ C H a
IV Pyrid-2-yl-Carboxomide N-p-Toluene sulphonyl
1. 2. 3. 4. 5.
II! Glutarimide
V Benzofur-2-y/-Carboxomide N-p-Toluene sulphonyl
Mary M. Rising, Francis M. Parker and Dorothy R. Gaston, J. A m. chem. Soc. 56, 1178 (1934). E. M. Preis and W. P. Peskov, J. phys. Chem. USSR 3, 43 (1932). W.J. Pope, Br. pet. 328,506 (1929). M. V. Suba Rao and T. R. Seshadri, Proc. Ind.Acad. 1, 10A (1939). Cambi, L. Kanonica Lingi and Ruggero, Deleone Atti., Accad. Nazi. Lincei, Rend. Classi. Sci Fis. Mat. Enat. 18, 467 (1955). 6. H. V. Malnistadt and D. A. Vassallo, Analyt. Chem. 31,462 (1959). 7. Franco Gaslini and Lucio, Z-Nahum,Analyt. Chem. 31,989 (1959).