Showing papers on "Photoemission spectroscopy published in 1971"

Photoemission Measurements of the Valence Levels of Amorphous Si O 2

Abstract: The complete valence band in amorphous Si${\mathrm{O}}_{2}$ has been examined by photoelectron spectroscopy at photon energies of 21.2, 26.9, 40.8, and 1486.6 eV. The spectra show emission from an 11.2-eV-wide $p$-derived valence band and from the oxygen $2s$ level at 20.2 eV below the valence-band edge. Four pieces of structure in the $p$ bands are related to the single bonding and the two nonbonding orbitals of the ${\mathrm{O}}^{\ensuremath{-}\ensuremath{-}}$ ion. A narrow, nonbonding level found at the valence-band edge may cause lattice trapping of valence-band holes.

The Jahn-Teller Effect in the Electron Spectrum of Methane

Abstract: The high resolution He I photoelectron spectrum of the (a12t25)2T2 < - (a12t26)1A1 transition in methane has been recorded and analyzed and a value has been obtained for the adiabataic ionization potential. The electron spectrum resulting from ionization of a t2 electron is a composite of at least three overlapping electronic bands which are separated by several tenths of an eV. These bands are the split components of the 2T2 electronic state of the CH4+ ion which is distorted by strong Jahn-Teller forces. The symmetry of the molecule in these three electronic states is believed to be, in order of increasing energy, D2d

Threshold Photoelectron Detector for Use in the Vacuum Ultraviolet

Abstract: The device described responds selectively to those photoelectrons that are formed practically at rest in a gaseous target. The energy discrimination is achieved by accelerating the charged particles to reject those formed with appreciable transverse velocity. When this is used in connection with a light source of continuously variable wavelength over the range 10–20 eV, the resulting threshold photoelectron spectra allow the direct spectroscopic determination of ionization energies within a few millielectron volts. The potential of the method for detection of direct ionization and suppression of autoionization is illustrated by measurements of argon, krypton, and xenon. Simultaneously, ions can also be detected by use of a mass spectrometer. Thus the threshold photoelectron spectrum can be correlated with the photoion spectrum; and it is suggested that the method is applicable to coincidence measurements between electrons and ions.

On the Photoelectron Spectrum of NO

Abstract: Abstract The photoelectron spectra of NO have been remeasured with 584 Å and 304 Å He lines at high resolution and the energies of the bands have been determined by calibration against argon. A weak He I line 320.4 Å has been found to cause the small peak at 20.4 eV, which was assigned earlier as the c 3II state. The c 3II and B 1II states have nearly the same energy, 21.7 eV. The vibrational structure of the B′ 1Σ+ state at 22.5 eV has been resolved.

Non-empirical calculation of the electronic energy levels of the BF3 + ion. Interpretation of the photoelectron spectrum of BF3

Abstract: (1971). Non-empirical calculation of the electronic energy levels of the BF3 + ion. Interpretation of the photoelectron spectrum of BF3. Molecular Physics: Vol. 21, No. 5, pp. 939-942.

Ionization Potentials of the Difluoroamino Radical by Photoelectron Spectroscopy and INDO Calculations

Abstract: The photoelectron spectrum of the NF2 radical has been measured. The spectrum shows evidence for three vertical ionization potentials at 12.10, 14.60, and 16.38 eV. The adiabatic first ionization potential was found to be 11.62 eV. LCAO–INDO calculations have been employed to deduce the excitation energies of the NF2+ ion, and these are compared with the experimental values. The calculations indicate that the 1A1 state of the bent NF2+ ion is lower in energy than the linear 3Σ− state. Vibrational structure is clearly seen on the first band (1250 cm−1) and on the second (520 cm−1), and there is evidence that both progressions belong to the symmetric stretching mode ν1(a1).

Direct Evidence for Disorder Effects on the Electronic Structure of Selenium

Abstract: The electron states of amorphous and single-crystal trigonal selenium were investigated by high-resolution photoemission spectroscopy. Structures due to a high density of states 0.2 eV below and 6.9 eV above the valence-band edge for crystalline Se are absent in the amorphous phase, but structures due to deeper valence-band density-of-states features remain. The results provide the first direct evidence for disorder effects on the Se valence and conduction bands and agree with calculations for amorphous Se using a pseudopotential formalism.

Auger Electron Spectroscopy of Graphite Fibre Surfaces

Abstract: THE atomic composition of the external surface of graphite fibres has recently been investigated by the application of high energy photoelectron Spectroscopy1. Because the structural characteristics of graphite/epoxy composites are usually evaluated by measuring the short beam shear strength (a measure of interlaminar shear), it is important to be able to correlate this with the bonding between the fibres and the matrix material. High energy photoelectron Spectroscopy involves measuring the binding energy of core electrons excited by low energy X-rays, and changes in the chemical environment in a region between 100 A and 150 A thick are reflected by a subsequent slight shift of the energy of the core electrons.

Photoelectron spectrum of B4Cl4

Abstract: The He(I) photoelectron spectrum of B4Cl4 is interpreted in terms of a simple molecular orbital scheme, and evidence for B–Cl π bonding is deduced.