Flash photolysis of lead tetramethyl

Abstract

The photolytic decomposition of lead tetramethyl has been studied in the vapour phase using a high-intensity flash of light and absorption spectroscopy. It has been found that more than 90 % of the theoretical amount of lead originally present in the sample had been deposited after a sample of lead tetramethyl had been subjected to a light flash of energy 2500 J. During the photolysis an absorption system in the region of 3000 A has been observed with a lifetime not exceeding 400 psec. Unequivocal evidence has not been obtained to make a positive assignment of the new spectrum but shifts in the band system, when a deuterated sample of lead tetramethyl is photolyzed under identical conditions, leave no doubt that a mode involving hydrogen atoms in the upper state has been excited. The experimental conditions are such that a transition due to the free methyl radical or a lead polymethyl radical seems most likely to be responsible for the band system.