Laser-jet photochemistry: the photofragmentation of triplet 1,1,3,3-tetraarylpropane-1,3-diyls and their role in the photometathesis between diarylcarbenes and 1,1-diarylethylenes

Until recently the only method available for studying the photochemistry of transient photochemical intermediates was to stabilize them in low-temperature matrices where their lifetimes are increased to the point where conventional low intensity light sources can induce photochemistry. During the past several years, pulsed excimer laser sources have made it possible to study the photochemistry of transient intermediates under ambient conditions. The authors have recently developed a laser-jet technique for the study of transient intermediate photochemistry with a CW argon ion laser. This technique consists of irradiating a high velocity solution microjet (approx. 4.5 m/s approx. 100 ..mu..m in diameter) with the focused output of an argon ion laser (all UV lines, 333-364 nm, approx. 3W). Since microjet self-focusing and waveguide properties greatly enhance the light intensity within the jet, and since relatively large quantities of material can be processed by this method, multiphoton products can often be isolated from these jet reactions and characterized by conventional spectroscopic methods. In this report they describe the application of this laser-jet technique to the photochemistry of triplet 1,1,3,3-tetraarylpropane-1,3-diyls generated through the irradiation of diaryldiazomethanes in the presence of 1,1-diarylethylenes.