UV-ABSORPTION CROSS-SECTIONS OF A SERIES OF MONOCYCLIC AROMATIC-COMPOUNDS

Aromatic hydrocarbons are of increasing importance as components of ur ban volatile organic compounds. Besides gas-chromatographic techniques , the detection of aromatic hydrocarbons by Differential Optical Absor ption Spectroscopy (DOAS) is a promising alternative technique. The ab solute calibration of DOAS-instruments is straightforward: Only the ab sorption cross sections of the species of interest and the instrument function are required. In this work we present measurements of high-re solution gas phase UV-absorption cross section spectra of benzene (C6H 6), toluene (C7H8), p-, m-, o-xylene (C8H10), phenol (C6H5OH), benzald ehyde (C7H6O) and the cresol isomers (C7H8O), p-, m- and o-cresol in t he wavelength interval between 230 and 290 nm The spectral resolution is 0.11 nm(FWHM), except for o- and m-cresol, where the resolution is 0.32 nm (FWHM). These spectra can be used to calibrate DOAS-instrument s. From these absorption cross sections typical detection limits for t he atmospheric measurements with Long-Path-Differential Optical Absorp tion Spectroscopy are calculated to be in the range of a few ppt (phen ol), to a few 10 ppt (cresol, benzaldehyde, benzene, p-xylene), up to 200 ppt (o-xylene). The attainability of these detection limits is dem onstrated by measurements of atmospheric phenol and benzaldehyde. (C) 1997 Elsevier Science Ltd.