Angular distribution parameter as a function of photon energy for some mono- and diazabenzenes and its use for orbital assignment

摘要: Angle-resolved photoelectron spectra were obtained on a series of nitrogen-containing aromatic systems using synchrotron radiation as the ionizing source. The angular distribution parameter, ..beta.., was measured in photon energy range 12-27eV for first three orbitals 2-fluoropyridine, pentafluoropyridine, and pyridine, four pyrimidine pyrazine. parameter function is shown to be value assignment bands has been applied pyridine. fluoro-substituted pyridines provided information trend ..beta.. values nonbonding with predominant nitrogen lone-pair character. diazines demonstrated that could used orbital assignments even case partial band overlap. For pyridine overlap two ionic levels, consisting ..pi.. orbital, so severe unambiguous difficult but now possible. Experimental evidence presented sequence these levels (n) at lower ionization followed by orbital. relevance systematic investigations angle-resolved spectroscopy amore » homologous molecules discussed.« less