Chemical Mechanisms in Photoresist Systems: I . Photochemical Cleavage of a Bisazide System

We have investigated the familiar photoresist system of cyclized polyisoprene + bis(4‐azidobenzal)cyclohexanone by the methods of infrared and u.v. spectroscopy, solvent extraction, and thin layer chromatography. The principal photoreaction is the simultaneous cleavage of both azido groups on a single molecule by absorption of a single photon with 43% quantum yield. The observed traces of monoazides and or other materials are insufficient to justify a biphotonic mechanism. The reacted bisazide (bisamine and/or byproducts) acts as a quencher for neighbor bisazide molecules, producing a complicated kinetic behavior which may simulate a second‐order (biphotonic) reaction.