COMMUNICATIONS TO THE EDITOR
3676
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The combination (VO-D 8110~) for the free hybrid molecule :Jhould have a frequency near 5050 cm-', judging from the sum ol the fundamentals (3680 1402 cm-l) .5 I n conclusim, it must be stressed that the said pair of HDO bands coincidos precisely with a fairly strong combination band of the major component, DzO (at about 5080 cm-l). The extinction thickness of that band has been estimated3 a t 1 mm. Under such conditions accurate measurements become almost impossible.
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PAUL A. G I G U ~ R E
DEPARTMENT O F CNWIMISTRY U N l V E R S I T 6 L.4 VAL Q U ~ B E CCANADA , l%EEGEIVED JULY 26,
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Figure 1. Spectrum of transient in 0.4 M 11~SO45 nsec after a 12-nsec 96-krad electron pulse ( I = 2.5 cm). 1972
so4-
Concerning the Direct Effect in the Radiolysis o f 0.4
M Sulfuric, Acid
Publication costs assisted by the French Atomic Energy Commission
Sir: Mat them, Mahlman, and Sworski' have recently studied t h e ('OCo y radiolysis of CeIV in aqueous solutions containing CeIV,CeIII, HCOOH, and various concentrations of sulfuric acid. Kinetic analysis of their results led thc authors to conclude that the radical SOe- was formed bj7 direct action upon sulfuric acid. The yield of SO4- radicals formed in this way, though small, was significant even for 0.4 M solutions: Gso,0.20. In the course of work on the pulse radiolysis of vanadium(1V) and (Ti) in aqueous solutions containing sulfuric acid we havc studied the absorption spectra of deaerated 0.4 M solutions of sulfuric acid, free from other solutes, subjected to a 12-nsec pulse of 1.8-MeV electrons produced by a modified Febetron 707.d Under these conditions, we observed a transient species which waR present less than 10 nsec after the end of the pulse and nhich h a d the absorption spectrum shown in Figure f The spectrum corresponds to that att r i b u t ~ d i ~to - - ~the radical-ion 504- formed under other experimental condl tions, and we believe the transient species we observe t o be Sod- (or HSO4). Under our conditiona, this cannot be formed by the reaction OH 4- HS04----p H20 SO4-- since the rate constant of this reactior (8.4 >( IO5 sec-l)),Sis too low for it to contribute rignificantly, and we believe the radical =
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The Journml o j Physical Chemistry, V o l . 76, No. 24, 1979
to be produced by direct action upon sulfuric acid, as suggested by Matthews, Mahlman, and Sworski. The absorbed dose was determined from the amount of ferricyanide formed 100 nsec after the pulse in a neutral 0.1 M ferrocyanide solution containing nitrous ~ 600 M-l cm-';$ GOH G, = 5.F0) oxide ( € 4 4 0 ~ = and gave GE = 182 f 30 a t 450 nm for the ion-radical SO4-. If €450 = 1000 M-l em-1, as determined by the radiolysis of sulfuric a ~ i d ,we ~ ,find ~ Gs0,- to be 0.18 f 0.03 in good agreement with the value already cited.' The effect of sulfuric acid concentration upon the yield of transient and t)he decay kinetics of the transient will be the subject of a subsequent article.
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(1) R. W. Matthews, H . A. Mahlman, and T.J. Bworoki, J . Phys. Chem., 76,1265 (1972). (2) L. Gilles, B. Lesigne, C. Ferradini, and J. Pucheault, t o bepublished. (3) B. Lesigne and R. Sauneuf, to be published. (4) L. Dogliotti and E. Hayon, J. P h y s . Chem., 71, 2511 (1967). (5) E. Heckel, A. Henglein, and G. Beck, Ber. Bunsenges. Phys. Chem., 70,149 (1966). (6) A. K. Pikaev and C. I. Zolotarevskii, Iza. Alcad. Nazik SSSR,188 (1967). (7) D. M. Brown and F. R. Dainton, Trans. Faraday. Soc., 62, 1139 (1966). (8) C. Ferradini, "Actions Chimiques e t Biologiques des radiations," &I. Haissinsky Editeur, X e s6rie, Masson, Paris, 1966. (9) 8. R. Cohen and R. A. Plane, J.Phys. Chem., 61, 1096 (1957). (IO) E. D. Black and E. Hayon, ibid., 74, 3199 (1970).
DRA/SRIRMA, CEN.SACLAY 91190 GIF S/YVETTE,FRANCE C. N. R. S. 94200 IVRY, FRANCE R X C E ~ VAUGUST ED 8, 1972
B. LESIGNE* C. FERRADINI J. PUCEIEAULT
