Photofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region via superexcited states studied by fluorescence spectroscopy

Photofragmentation of tetrahydrofuran molecules in the vacuum-ultraviolet region, producing excited atomic and molecular fragments, has been studied over the energy range 14-68 eV using photon-induced fluorescence spectroscopy. Excited hydrogen atoms H(n), n = 3-11, have been detected by observation of the H? to H? lines of the Balmer series. The diatomic CH(A2?), CH(B2?-) and C2(d3?g) fragments, which are excited to low vibrational and high rotational levels are identified by their A2?->X2?r, B2?-->X2?r and d3?g->a3?u emission bands, respectively. Dissociation efficiency curves for CH(A2?) and H(n), n = 3-7, have been obtained in the photon energy ranges from their appearance thresholds up to 68 eV. The appearance energies for CH(A2?) and H(n), n = 3-7, have been determined and are compared with estimated fragmentation energy limits in order to discuss the possible fragmentation processes. In the present studies, superexcited states of tetrahydrofuran are found, which dissociate into the above excited atomic and molecular fragments.