Absorption cross-section measurements of ortho-xylyl radical in the 460.1–475.1 nm region and investigation of its temperature and pressure dependence using cavity ringdown spectroscopy

Abstract

The gas phase absorption cross-sections of o-xylyl radical were measured in the wavelength range of 460.1–475.1 nm with 0.2 nm resolution at 298 K and 40 Torr using pulsed laser photolysis-cavity ringdown spectroscopy (PLP-CRDS) and was found to be maximum at 468.3 nm [σo-xylyl468.3nm=(1.58 ± 0.38) × 10−18 cm2 molecule−1]. The temperature dependency of the cross-section was: σo-xylyl468.3nmT263-338K=[(6.39 ± 0.64) × 10−21] + [(2.60 ± 0.27) × 10−15 exp(−0.026 T/K)] cm2 molecule−1. A negligible pressure dependency was observed in the studied range of 40–95 Torr. The Time Dependent Density Functional Theory (TD-DFT) calculations were also performed to compute the visible absorption spectrum of o-xylyl radical.