Pulsed CO₂ laser induced multiphoton decomposition of cyclobutanone: A comparison of predictions for three models of decomposition probability vs. fluence

Abstract

The multiphoton decomposition (MPD) probability (f) for photolysis of cyclobutanone (pressure: 0.333 kPa) with a pulsed (pulse width: 40 ns) CO₂ laser tuned to the 9P(20) line, was studied,in a collimated beam geometry, as a function of fluence (ϕ=0.75 to 11.7 J/cm²). The values off (ϕ) were fitted to three suggested 1- or 2-parameter models. Models with two parameters correlated the experimental values equally well, whereas a 1-parameter model was less accurate for low fluences. The MPD yield for two focussed beam geometries was measured and compared to predicted yields obtained by integrating the three models forf (ϕ) over the focussed beam geometries. All three models predicted yields which agreed well with the measured values.