ANGULAR-DISTRIBUTION VALENCE PHOTOELECTRON-SPECTRA OF NITRIC-OXIDE

The first X̃1Σ+ band in the photoelectron spectrum of NO shows considerable vibrational dependence of the anisotropy parameter at He(I), Ne(I) and Ar(I) wavelengths. In the latter case this is predominantly due to autoionization, though for the earlier vibrational components (and particularly in the 104.8-nm series) direct ionization remains strong. For He(I) and the corresponding vibrational components of the Ne(I) spectrum, on the other hand, there is no detectable autoionization contribution. In addition the angle-independent intensities agree well with the Franck-Condon factors, which further emphasizes the uniqueness of such β(ν′) dependencies. Among the higher bands the most notable anisotropy parameter variation occurs for the ã3Σ+ state with Ne(I) radiation; here autoionization is again indicated. The conditions necessary for the existence of autoionization and direct ionization as well-defined independent processes are also explicitly discussed. © 1979.