WAVELENGTH-DEPENDENT LASER-INDUCED FRAGMENTATION OF NITROBENZENE

This paper describes the wavelength-dependent yield of some of the positively charged ions resulting from the interaction of a UV laser beam with nitrobenzene molecules in a high vacuum chamber. In the wavelength region 245-250 nm, which spans the two-photon ionisation threshold (249,2 nm), the CnHm+ fragments display a similar wavelength dependence, whereas the behaviour of the mass 30 fragment (NO+) is markedly different. The wavelength dependence of the fragment-ion yields suggests that the parent molecule dissociates into C6H5 plus NO2. Additionally, at high pulse energies, ionisation of atomic carbon demonstrates that the dissociation process generates carbon atoms in both ground and excited states.