Oxygen Quenching Measurements for the S 1 and S 2 Fluorescence of Gas-Phase Fluoranthene

Abstract

The fluorescence emission of the fluoranthene molecule has been investigated at excitation wavelengths varying from 240 to 360 nm, and conducted from near collision-free conditions to atmosphericpressure conditions. The oxygen quenching rate for the fluorescence of the F₁ band (S₁ → S₀ transition) of fluoranthene at 340 nm excitation wavelength was found to be 1 × 10⁹ L mol⁻¹ s⁻¹. The quenching rate for the F₂ band (S₂ → S₀ transition) was found to be 100-fold greater for the wavelength region investigated. The wavelength dependency of the oxygen-quenching constants of the two transitions was also established in the excitation range from 240 to 332 nm. The influence of oxygen and nitrogen pressure on the spectral fluorescence bandwidth of fluoranthene and the oxygen-quenching constants for the S₁ and S₂ bands are reported. The results shed some light on fluoranthene's unusual inertness to oxygen quenching.