Joseph E. Lester

A study of nitric oxide adsorbed on nickel oxide, cobalt oxide, and graphite by X-ray photoelectron spectroscopy

Abstract The nitrogen 1s binding energy of nitric oxide adsorbed on nickel oxide, cobalt oxide and graphite was measured at several temperatures by X-ray photoelectron spectroscopy. For the oxides, a temperature dependent range of binding energies was observed, but for graphite the nitrogen 1s binding energy was independent of temperature. The values obtained suggest that significant back donation of electrons occurs from the oxides to the adsorbed nitric oxides, but no back donation occurs from graphite to adsorbed nitric oxide. However, adsorption did not cause changes in the binding energy of substrate core electrons. It is believed that unless the mean free path of electrons is short, the total photoelectron signal will not reveal changes in binding energy of electrons from substrate atoms at the surface.

Mixed and partial oxidation states. Photoelectron spectroscopic evidence

Abstract X-ray photoelectron spectra of the single valence platinum complexes K 2 [Pt(CN) 4 ] · 3H 2 O(1),K 2 [Pt(CN) 4 ]Cl 0.3 · n H 2 O(2) and K 2 [Pt(CN) 4 ]Cl 2 · 3H 2 O(3) and the mixed valence compound [Pt II (C 2 H 5 NH 2 ) 4 ]Cl 4 · [Pt IV (C 2 H 5 NH 2 ) 4 Cl 2 ] · 4H 2 O(4) have been measured. It is found that one can distinguish clearly between mixed and single valence compounds by electron spectroscopy. The Pt spectrum of (4) is a superposition of a Pt II and Pt IV spectrum. The chemical shift between (1) and (3) is normal, however (2) shows an anomalous low binding energy for the Pt 4f electrons. The importance of using reliable reference peaks for obtaining absolute binding energies is emphasized.

Valence band photoelectron spectra of platinum cyanides

Abstract Valence band X-ray photoelectron spectra of K 2 [Pt(CN) 4 ]·3H 2 O (1), K 2 [Pt(CN) 4 ]Cl 0.3 · x H 2 O ( 2 ), and K 2 [Pt(CN) 4 Cl 2 ]·3H 2 O ( 3 ), and the ultraviolet photoelectron spectrum of ( 2 ) have been recorded. These spectra imply that the binding energy of the highest occupied molecular orbital (HOMO) in ( 1 ) is greater than in ( 2 ). A band-like character for the HOMO of ( 2 ) with finite electron density at the Fermi level is consistent with this observation. The photoelectron spectra are correlated with the solid state electronic absorption spectra. Shifts in the K 3 binding energies are attributed to considerable differences in lattice site potentials between ( 1 ) and ( 2 ).

Alkali halide surfaces: Measurements and modeling of adsorbate motions and reactions at surface defects

Results are presented for a mass spectrometric study of reactions between alkali halide molecular beams and vaporizing single crystals of different alkali halides. Shuttering the beam yields a temperature dependent decay of reaction products from their steady state surface fluxes. We determined Arrhenius pre‐exponentials and activation energies from the decay rates of unreacted beam diatomic (monomer), dimer products, and beam–crystal ion exchange products (monomers). The kinetic curves were primarily composed of a slow decay with a smaller amount of a faster decay. The pre‐exponentials and activation energies exhibit a close correlation (lnAαEa) for energies ranging from 2–57 kcal/mole. This compensation effect has allowed our direct measurement of several processes in a narrow range of first order decay constants (0.02–4.0 sec−1). Analysis of the decay curves and extensive modeling of the crystal surface defects identify the measured activation barriers with specific surface processes. We have assigned ...

On the relation of bulk diffusion to vaporization in cesium chloride

Abstract The vaporization rate of single crystals of CsCl in the region of the phase transition has been measured. It is not proportional to the bulk diffusion rate of the more slowly diffusing lattice ion as has been postulated.