Gas-phase absorption cross sections of 24 monocyclic aromatic hydrocarbonsin the UV and IR spectral ranges

Absorption cross sections of 24 volatile and non-volatile derivatives of be nzene in the ultraviolet (UV) and the infrared (IR) regions of the electrom agnetic spectrum have been determined using a 10801 quartz cell. For the UV a 0.5 m Czerny-Turner spectrometer coupled with a photodiode array detecto r (spectral resolution 0.15 nm) was used. IR spectra were recorded with an FT-IR spectrometer (Bruker IFS-88, spectral resolution 1 cm(-1)). Absolute absorption cross sections and the instrument function are given for the UV, while for the IR, absorption cross sections and integrated band intensitie s are reported. The study focused primarily on the atmospherically relevant methylated benz enes (benzene, toluene, o-xylene, m-xylene, p-xylene, 1,2,4-trimethylbenzen e, 1,3,5-trimethylbenzene, ethylbenzene, styrene) and their ring retaining oxidation products (benzaldehyde, o-tolualdehyde, m-tolualdehyde, p-toluald ehyde, phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,4-dimeth ylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-d imethylphenol, 3,4,6-trimethylphenol and (E,Z)- and (E,E)-2,4-hexadienedial ). The UV absorption cross sections reported here can be used for the evaluati on of DOAS spectra (Differential Optical Absorption Spectroscopy) for measu rements of the above compounds in the atmosphere and in reaction chambers, while the IR absorption cross sections will primarily be useful in laborato ry studies on atmospheric chemistry, where FT-IR spectrometry is an importa nt tool. (C) 1999 Elsevier Science Ltd. All rights reserved.