Some applications of the optical approximation to radiation chemistry

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1970

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Abstract

Based on the optical approximation an attempt has been made to calculate the average energy of excited species (E[lowered x]) and the average energy of ionic species (E[lowered i]) including the average energy of secondary electrons (E[lowered s]) for the gases under study. Various methods of calculation of E[lowered i] are discussed. The values of E[lowered x] are also calculated from the energy balance equation. The energy deposition function of ethane is calculated from the photoelectron spectrum and compared with that from the photoionization data. The energy distributions of secondary and subexcitation electrons are derived within the theoretical frame work of the optical approximation. Thus, the average energy of secondary electrons and that of subexcitation electrons (E[lowered se]) can be calculated from the energy spectra. The E[lowered s] is compared with the difference of the (E[lowered i] + E[lowered s]) from the optical approximation and the E[lowered i] from other methods. The E[lowered se] is compared with the results calculated from the ElKomoss-Magee formula. The energy balance equation is applied to calculate the relative yields of excited and ionic species, N[lowered x]/N[lowered i], for the gases under investigation. The calculated results, in most cases, are in fair agreement with the experimental results provided that the energetic secondary electrons are taken into consideration. The disagreements in some gases are discussed. The yields of excited states in argon are evaluated. An interpretation of the apparent failure in the previous application of the optical approximation in the calculation of yields of excited states in argon is offered.

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