Communications to the Editor
1029
References and Notes (1) J. W. Hunt, R. K. Wolff, M. J. Bronskill, C. D. Jonah, E. J. Hart, and M. S. Matheson, J . Phys. Chem., 77, 425 (1973). (2) A. Kupperman in “Physical Mechanisms In Radiation Biology”, Technical Information Center, Office of Information Services, US. Atomic Energy Commision, Washington, D.C.,1974, p 155. (3) (a) A. H. Samuel and J. L. Magee, J. Chem. Fhys., 21, 1080 (1953); (b) A. K. Ganguly and J. L. Magee, ibid., 25, 129 (1956). (4) A. Kupperman, “Radiatlon Research”, G. Sllini, Ed., North Holland Publishing Co., Amsterdam, 1967 (see references therein to earlier computations by Kupp@rmanand others). 151 H. A. Schwarz. J. Phvs. Chem.. 73. 1928 (1969). (6j R. K. Wolff, M. J. Bronsklll, J. E. Aldrich, and J. W: Hunt, J. Phys. Chem., 77, 1350 (1973). (7) c. D. Jonah, M. S. Matheson, J. R. Miller, and E. J. Hart, J . Phys. Chem., 80, 1276 (1976). (8) J. E. Fanning, C. N. Trumbore, P. G. Barkley, and J. Olson, to be published. (9) 0. A. Kenney and D. C. Walker, J . Chem. Phys., 50, 4047 (1969). (10) D. E. Lea, Proc. Cambridge Phil. Soc., 30, 80 (1934). (1 1) R. L. Platzman in “Radiation Biology and Medicine”, W. D. Claus, Ed., Addison Wesley, Reading, Mass., 1958, pp 15-72 (see earlier references therein). (12) A. M. Raitsimring, V. M. Moralev, and Yu. D. Tsvetkov, Khim. Vys. Energ., 9, 517 (1975) (translation by Plenum Press). (13) R. L. Platzman, Natl. Aced. Sci. Res. Counc., Pub/. No. 305, 34 (1953). (14) J. K. Thomas, Adv. Radiat. Chem., 1, 111 (1969). (15) J. L. Magee, Radiat. Res. Suppl., 4, 20 (1963). (16) A. Mozumder and J. L. Magee, Int. J . Radiat. Phys. Chem., 7, 83 (1975). (17) A. Mozumder and J. L. Magee, J . Chem. Phys., 45, 3332 (1966); see flgures on p 67 of Adv. Radiat. Chem., 1, (1969). (18) J. E. Fanning, Jr., FhD. Thesis, 1975, University of Delaware, Newark, Del. (19) (a) Department of Chemistry. (b) Deparbnent of Chemical Engineering. Depafiments of Chemistry and Chemlcal Englneering University of Delaware Newark, Delaware 1971 1
L
0
I
I
2
4
!
6
1
I
TlME I V I N
I
I
10
8
14
12
)
Figure 1. Plots of log ( R e - R ) / ( R , - R,) vs. time (min), where Ro is the hydrogen free resistance and R, is the value at equilibrium, at an absorption temperature of 55.6 “C for the specimens annealed at: (A) 200, (B) 300, (C) 500 “C.
James E. Fanning, Jr.”’” Conrad bl. Trumborelga P. Glenn BarkleyiSa David R. ShortlSa Jon H. Olson1sb
Received May 17, 1976;Revised Manuscript Received January 27, 1977
,
0,2 * O o 1
, 200
L&$ ~
300 400 500 ANNEALING TEnPERATURE (‘c
p-
600
Absorption Rate of Hydrogen by Cold-Worked Palladium
Figure 2. (A) Dependence of rate constant ( k )on annealing temperature (absorption temperature 55.6 “C). (B) Effect of surface treatment (oxidation-reduction) on k for annealed specimens.
Sir: The problem of absorption of H2 by palladium has been under consideration for many years. It is well known that the elementary steps occurring during absorption from the gas phase are (a) surface processes and (b) internal diffusion. It has been pointed out that at low temperatures (
