Laser photolysis of naphthoquinone diazide in cyclohexane - two-laser chemistry

Article abstract of DOI:10.1002/bbpc.19940980803

The laser photochemistry of 1,2-naphthoquinone-diazide-(2)-5-sulfonic acid phenylester in cyclohexane has been investigated. The photolysis experiments have been done using a KrF laser pulse (generation pulse) and a nitrogen laser pulse (transformation pulse) with various time delay from 40 ns up to 1 s. At a time delay between the two laser pulses in the μs-region, the formation of indene and cyclohexyl-indene derivatives has been observed, additional to the corresponding indenecarboxylic acid. The laserspecific formation of these compounds is the result of the electronic excitation of the intermediately formed ketene and its reaction by decarbonylation. The time delay for getting a high yield of the indene and the cyclohexyl-indene derivatives correlates closely with the rise time and the life time of the ketene.