Fast decay of the visible band electron in e-irradiated crystalline ice at low temperature: The isotope effects and the role of a mobile proton in the decay

Journal Article · Fri Oct 15 04:00:00 EDT 1982 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.444342· OSTI ID:6773399

Kawabata, K; Nagata, Y; Okabe, S; Kimura, N; Tsumori, K; Kawanishi, M; Buxton, G V; Salmon, G A

The trapped electron which absorbs in the visible region in crystalline ice e/sup -//sub vis/ has been studied by pulse radiolysis in the low temperature range 6 to 77 K using 2 ..mu..s pulses, and above 77 K using pulses of 40 ps to 6 ns width. The half-life of e/sup -//sub vis/ in ice around 77 K is unusually short, 8 ns in H/sub 2/O ice and 120 ns in D/sub 2/O ice. The decay of e/sup -//sub vis/ in ice is found to fit Hummel's empirical equation for the decay by geminate ion recombination in a spur. Several other pieces of evidence indicate that the decay occurs in a spur. Electron tunneling from e/sup -//sub vis/ to the OD radical does not occur in D/sub 2/O ice. It is concluded that a proton (H/sub 3/O/sup +/) or a deuteron (D/sub 3/O/sup +/) produced in a spur by the irradiation migrates through ice to react with immobile e/sup -//sub vis/ in the same spur, and that the half-life of e/sup -//sub vis/ is determined by the mobility of the proton or deuteron. The Arrhenius plot of the half-life in the range 100 to 6 K is nonlinear and shows an activation energy of 20 meV at higher temperatures and much smaller values at temperatures below 50 K (1 meV below 15 K). The causes of the unusual Arrhenius plot and the isotope effect on the proton mobility are discussed.

• Research Organization: Radiation Center of Osaka Prefecture, Shinke-cho, Sakai, Osaka, 593 Japan
• OSTI ID: 6773399
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 77:8; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
ICE
ISOTOPE EFFECTS
LEPTONS
LOW TEMPERATURE
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOLYSIS
SPECTRA
TRAPPED ELECTRONS
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE