UV-absorption cross sections of a series of monocyclic aromatic compounds

Aromatic hydrocarbons are of increasing importance as components of urban volatile organic compounds. Besides gas-chromatographic techniques, the detection of aromatic hydrocarbons by Differential Optical Absorption Spectroscopy (DOAS) is a promising alternative technique. The absolute calibration of DOAS-instruments is straightforward: Only the absorption cross sections of the species of interest and the instrument function are required. In this work we present measurements of high-resolution gas phase UV-absorption cross section spectra of benzene (C6H6), toluene (C7H8), p-, m-, o-xylene (C8H10), phenol (C6H5OH), benzaldehyde (C7H6O) and the cresol isomers (C7H8O), p-, m- and o-cresol in the 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-instruments. From these absorption cross sections typical detection limits for the atmospheric measurements with Long-Path-Differential Optical Absorption Spectroscopy are calculated to be in the range of a few ppt (phenol), to a few 10 ppt (cresol, benzaldehyde, benzene, p-xylene), up to 200 ppt (o-xylene). The attainability of these detection limits is demonstrated by measurements of atmospheric phenol and benzaldehyde.