Vibrational relaxation of excited acetaldehyde vapor. A search for unquenchable species

Abstract

Quantum yields of intersystem crossing for the system acetaldehyde-CO 2 were determined at room temperature as a function of pressure (5–2200 torr) and excitation wavelength (250–330 nm). Fluorescence decay times of 10 torr of acetaldehyde were measured as a function of excitation wavelength (275–325 nm). The results are consistent with the formation of an nπ * singlet state which can be totally relaxed by collision. No evidence was found a collision insensitive excited state. The lifetime of the nπ * triplet state of acetaldehyde is also reported.