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

Journal Article · Wed Jun 29 04:00:00 EDT 1983 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00351a019· OSTI ID:5382398

Piancastelli, M N ^[1]; Keller, P R; Taylor, J W; Grimm, F A; Carlson, T A

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1. Univ. of Wisconsin, Madison

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

• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5382398
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:13; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500 -- Photochemistry
AZINES
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ENERGY RANGE
EV RANGE
EV RANGE 10-100
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
NITRO COMPOUNDS
NITROBENZENE
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PYRAZINES
PYRIDINE
PYRIDINES
PYRIMIDINES
RADIATIONS
SPECTROSCOPY
SYNCHROTRON RADIATION