Threshold photoelectron studies of isoxazole over the energy range 9.9-30Â eV

The threshold photoelectron spectrum of the isoxazole molecule, C3H3NO has been measured over the photon energy range 9.9-30 eV with the use of synchrotron radiation. In the 9.9-10.8 eV range, corresponding to photoionization from the highest occupied molecular orbital 3a″(π3), seven well resolved vibrational series have been observed and their modes are tentatively assigned. A strong adiabatic ionization, with an energy of 11.132 ± 0.003 eV corresponding to the 2a″(π2) band, has also been observed. This is followed by a single vibrational series of the νC-H stretching mode. Photoelectron bands in the energy region 13-30 eV have also been identified, some for the first time.