Trace detection of benzene vapour in a simple ion chamber employing laser-induced resonance-enhanced multiphoton ionization in the 246–264 nm wavelength region
Abstract
A tunable, pulsed laser source has been used to ionize trace amounts of benzene vapour in a simple ionization chamber. By scanning the laser wavelength over the 1B2u–1A1g transition of the benzene molecule, it is possible to differentiate the contribution to the total ionization yield due to the resonance-enhanced multiphoton ionization (REMPI) of the benzene sample from that due to background ionization from other unidentified molecular species. The wavelength-dependent ionization fingerprint of benzene is verified by comparison with that of benzene vapour recorded in a laser TOF mass spectrometer.