Photoelectron spectra of acetaldehyde and acetyl halides

The He I photoelectron spectra of acetaldehyde and acetyl fluoride, chloride and bromide have been obtained. The spectra are interpreted in terms of molecular orbital structures, by comparison with results for related molecules and by a consideration of the inductive and resonance effects. The results of CNDO/2 and INDO semi-empirical calculations are also reported. It is found that the oxygen “lone pair” is progressively stabilized as the electronegativity of the halogen increases. The vibrational structure of the first photoelectron band of acetaldehyde is compared with the observed structure of Rydberg transitions in the optical spectrum.     

Photoelectron spectra of styrenes

The photoelectron spectra of styrene and its methyl derivatives were measured and interpreted. The vinyl group twisted by the steric hindrance of the α- or orthomethyl group was found to play an important role in the interpretation of the photoelectron spectra of these compounds. The dependence of the higher occupied π orbital energies of styrene upon the twist angle of the vinyl group was estimated from the experimental data.     

Photoelectron spectra of fluorine-substituted diazabenzenes

The high resolution He 584 Å photoelectron spectra of ten fluorine-substituted diazabenzenes are presented. By means of fluorine substitution the analysis of the photoelectron spectra of the parent compounds can be made more definite. “Lone-pair” ionization potentials are shown to correlate well with data calculated by a modified and iterative version of the extended Hückel method.     

Photoelectron spectra of adsorbed carbonates

In order to provide photoelectron spectra for analytical purposes, X-ray and ultraviolet photoelectron spectra for known surface species have been measured. The surface carbonate on Ag(110), formed by reacting gaseous CO₂ with pre-adsorbed atomic oxygen, yields C 1s and O 1s peaks at 287.7 and 529.9 eV, respectively. The UPS results show features due to surface CO₃ which scale well with those for bulk carbonates. These observations, coupled with the increase in work function that accompanies carbonate formation, suggest strongly that this surface species is negatively charged.     

Photoelectron spectra of bicyclic peroxides

The He(I) photoelectron spectra of nine bicyclic alkyl peroxide have been recorded. The first peaks are assigned by comparison with results of a MINDO/3 calculation. A correlation between the split of the first two ionization potentials and the OO torsional angle Θ is found.     

Photoelectron spectra of chromium tetranitrosyl

The ultraviolet and X-ray-excited photoelectron spectra of Cr(NO)₄ are reported. The electron binding energies, shake-up spectra, relative peak intensities and the Auger peak kinetic energies have been measured, and are compared to the spectra from gas-phase NO, from NO adsorbed on a transition metal surface, and to SCF-MS calculations. The theoretical calculations are utilized to obtain ionization energies and charge distributions, and consequently to discuss the bonding in nitrosyl complexes.     

Photoelectron spectra of styrenes ag

The photoelectron spectra of styrene and its methyl derivatives were measured and interpreted. The vinyl group twisted by the steric hindrance of the α- or orthomethyl group was found to play an important role in the interpretation of the photoelectron spectra of these compounds. The dependence of the higher occupied π orbital energies of styrene upon the twist angle of the vinyl group was estimated from the experimental data.     

Photoelectron spectra of fluorotribromomethane and fluorotrichloromethane

High resolution He(I) photoelectron spectra are reported for fluorotribromomethane CFBr₃ and fluorotrichloromethane CFCl₃. The assignments are based on CNDO/2 calculations, symmetry arguments, the fine structures of the bands, and comparison with the photoelectron spectra of related compounds. Linear relationships have been found between the Pauling electronegativity values for the halogen atoms and the observed vertical ionization energies corresponding to a₂ of a₂′ orbitals of CFX₃ and related compounds CHX₃, OPX₃, BX₃ and PX₃ (X = F, Cl, Br, I).     

Photoelectron spectra of the noble metals

High resolution ultraviolet photoelectron spectra excited by He^I and He^II radiation from the noble metals Cu, Ag, and Au are reported. A comparison of these data with others varying in excitation energy from 11 eV to 1487 eV shows very good agreement of the positions of structures in the spectra over this wide energy range.     

Cathodo-luminescence spectra of alkali halides

Cathodo-luminescence spectra of fourteen alkali halides and of some mixed crystals of NaCl and KCl have been studied. The spectra show broad structureless bands. In some ten halides it is possible to find a strong band whose peak position shifts towards longer wavelengths as the inter-atomic distance increases. For pottasium halides the relationship λ_max=1380d, where “d” is the inter-atomic distance, holds approximately but is not generally true. A mechanism of cathodo-luminescence in alkali halides has been postulated, and an interpretation of the above band and of some NaCl bands has been made on that basis.     

Photoelectron spectra of aminopyridines and cyanopyridines

Photoelectron spectra of 2?, 3?, and 4-aminopyridines and 2?, 3?, and 4? cyanopyridines were measured and assigned. The second highest occupied orbitals of the aminopyridines and 2? and 3-cyanopyridines and the highest occupied orbital of 4-cyanopyridine were concluded to be the lone pair orbital of the ring nitrogen.     

Photoelectron spectra of bis-cyclopentadienyl metal dihalides

He(I) and HE(II) photoelectron spectra are reported for (η-C₅H₅)₂MX₂ (M = Ti; X = F, Cl, Br, I: M = Zr, Hf; X = Cl, Br: M = Ta; X = Cl, Br) and (η-MeC₅H₄)₂MX₂ (M = Nb, X = Cl: M = Mo; X = Cl, Br, I). A substantial variation is found in the ordering of the halogen and cyclopentadienyl ionizations, the order being dependent on the metal as well as on the halogen. The compounds may be divided into three classes, namely, those in which the electrons in cyclopentadienyl e₁ orbitals ionize at a lower energy than those occupying halogen pπ orbitals, those in which halogen pπ electrons have lower ionization energy than cyclopentadienyl e₁ electrons and those in which the corresponding electrons arise from extensively delocalized molecular orbitals with significant contributions from both these categories of fragment orbital.     

Photoelectron spectra of nitrophenols and nitroanisoles

Photoelectron spectra (PES) of nitrophenols and nitroanisoles were measured and interpreted with the aid of previously reported PES of nitrobenzene, phenol and anisole. The effect of the intramolecular hydrogen bond is discussed in the case of o-nitrophenol.     

Raman spectra of alkali halides

In this article, we present a comparative study of the Raman spectra of alkali halides in relation to the lattice dynamics ofBorn andRaman. It is shown that the experimentally observed limit of the second-order spectra in almost all the cases can be explained well by the Lyddane-Sachs-Teller relation. It is also seen, while, an explanation of the second-order Raman spectrum of a crystal of diamond or zinc blende structure requires the frequencies from the critical points,W, Γ, X andL inBorn's analysis, the frequencies fromΓ, X andL alone are sufficient and necessary for an interpretation of the same onRaman's model. Some similarities in the determination of the long wave properties of crystals like elastic constants and limiting frequencies of the lattice vibrations in the symmetry directions in both the models are pointed out.     

Photoelectron spectroscopy studies of the band structure of silver halides

X-ray photoelectron spectroscopy has been used to probe the valence bands of the silver halides. Previous ultraviolet photoemission and optical absorption experiments together with the theoretical band structure calculations form the basis for interpretation of the spectra. Density of states maxima from the halogen p levels are clearly resolved from those of the silver 4d states. Additional splittings due to k space symmetry are observable and in the case of AgCl and AgBr, give excellent conformation of existing band structure calculations. The role of spin-orbit coupling is shown to be unimportant in determining the primary shape of the photoelectron spectrum. The spectrum of AgF shows the inversion of silver 4d and halogen 2p levels suggested by the optical absorption spectra and predicted by several recent band calculations. A new interpretation is proposed for the AgF optical spectrum in which the observed excitons are due to the forbidden Γ₁₂→ Γ₁ and Γ_25′ → Γ₁ tr the high temperature body centered cubic structure. These spectra clearly show the broadening of the I 5p levels which causes the band gap to decrease above the transition temperature.     

Photoelectron spectra of nitrones and nitrile oxides

The photoelectron spectra of five nitrones—N-t-butyl-, C-phenyl-N-methyl-, C-phenyl-N-t-butyl-, C-mesityl-N-methyl-nitrone and dihydroisoquin     

Photoelectron spectra of substituted anisoles and thioanisoles

The ground state electronic structure of p-anisoles and p-thioanisoles has been investigated with PES and in terms of CNDO/2 calculations coupled withIt is explained why the first band of p-anisoles shows a sensitivity to substituent effect greater than the first band of p-thioanisoles and why the hy     

Photoelectron spectra of some dipeptides containing glycine

The He(I) photoelectron spectra of several dipeptide-containing glycines are presented. Assignments are made for the bands characteristic of the peptide linkage and of the amino and carboxyl end groups. Mutual interactions among these units appear to be weak.