VACUUM-ULTRAVIOLET PHOTOCHEMISTRY .9. PRIMARY AND CHAIN PROCESSES IN PHOTOLYSIS OF HYDROGEN PEROXIDE

Evidence is presented for the occurrence of primary processes leading to the formation of both atomic and molecular hydrogen in the photolysis of H 2O2 at 1236 Å. Formation of OH in a primary process probably occurs as well. The latter is apparently the sole process required to explain the results at 1470 and 2537 Å. Processes leading to the formation of O(1D) account for less than 1% of the photochemical decomposition. Chain processes leading to the formation of O2 but not H2 occur at 1236 Å. The possibilities considered are a free radical chain and an energy chain. It is shown that the results are more consistent with the occurrence of an energy chain involving atomic hydrogen and vibrationally excited OH radicals. Emission of OH A 2∑ +→X2∏ (0,0) band at 3064 Å was observed during photolysis of H2O2 at 1236 and 1470 Å.