VUV optical-absorption and near-threshold electron energy-loss spectra of pyrazole

The gas-phase VUV absorption spectrum of pyrazole between 5 and 11 eV (250–110 nm) is reported, for the first time. The spectrum is diffuse, but is unusual because of the presence of a window resonance at about 7.8 eV, ascribed to interaction of a Rydberg state with an underlying valence continuum. A related near-threshold electron energy-loss spectrum reveals low-lying triplet states (3ππ*) at about 3.9 and 5.1 eV, respectively, and anionic states (electron/molecule resonances) having electron attachment energies of about 0.75, 2 and 6.5 eV, respectively. The UV-photoelectron He(I) spectrum has been re-measured with improved energy-resolution.