Dispersion relation and relative intensity for double-plasmon satellites

An expression for the dispersion relation and the relative intensity of double-plasmon oscillations and satellites has been derived by extending the dispersion relation and the extended Bohm and Pines Hamiltonian to second order. The calculated value of the relative intensity of the double-plasmon satellite for Be agrees fairly well with the value observed experimentally by other workers.     

The N2-broadened water vapor absorption line shape and infrared continuum absorption—II. Implementation of the line shape

The total line shape model of the previous paper is tested using a set of experimental room temperature H₂O continuum measurements of high quality. Parameters of the far wing component of the total line shape are determined from near band experimental data. Grating spectrometer measurements from 300 to 650 cm^?1 are used to determine unknown far wing parameters of the pure rotational band of H₂O. CO and HF laser measurements taken in the 5 and 3 μm regions are used to determine the far wing parameters of the ν₂ and ν₁, ν₃ fundamental bands, respectively.The total line shape model is applied to the 10 and 4 μm transmission windows with encouraging success. A significant increase in the self-broadening ability of H₂O over N₂ is predicted in the far wing. This procedure allows the proper modeling of the absorption coefficient vs H₂O partial pressure dependence in all window regions. A negative temperature is predicted by the model in the continuum. The observed rate of the temperature decrease is not predicted by the model; however, this limitation is related to the approximations made on the interaction potentials and the perturbation expansion of the Hamiltonians. Although the total line shape has limitations, it does demonstrate the importance of considering far wings of absorption lines in continuum absorption.     

The N2-broadened water vapor absorption line shape and infrared continuum absorption—I. Theoretical development

Attenuation of infrared radiation in the troposphere is dominated by water vapor absorption. Most past work on the spectroscopy of water vapor has been on the analysis of the rotational and vibrational bands. As a result, a thorough listing of line positions, line strengths, and half-widths exists today. Because of the weak continuum absorption in the water vapor windows centered at 10 and 4 μm, efforts to measure and model the continuum have not been as succesful as efforts in the analysis of the bands. Yet, a precise understanding of continuum absorption is important for long path energy transmission. For this reason, the study of the water vapor windows has had a long and speculative history.The purpose of this study is to demonstrate the importance of far wing phenomena in characterizing H₂O continuum absorption. A total line shape for water vapor-nitrogen interactions valid under tropospheric conditions is derived. The complexity of such a model is substantial and many approximations are necessary to obtain a tractable theory. This effort represents one of the initial attempts at a far wing line shape solution of continuum absorption. Application of the model to existing experimental data is presented in the following article.     

The conformational analysis of 1-haloalkanes by low resolution microwave spectroscopy

The low resolution microwave spectra of a series of 1-haloalkanes were studied. With the exception of 1-bromobutane only the all s-trans conformer and those gauche conformers in which a single dihedral angle is gauche were foud. By analyzing data from a homologous series, a gauche dihedral angle of 286 ± 4° was determined for the gauche conformers of the bromo and iodo species. An analysis of relative intensities of the 1-bromobutane and 1-iodobutane bands yielded standard Gibbs free energy differences.     

Energy spectra of ions sputtered from elements by O+2: A comprehensive study

The results of a comprehensive study of the energy distributions of ions sputtered from 31 pure elements and two compounds by a 5.5 keV O⁺₂ beam are presented. The spectra were determined under three different ambient conditions: residual vacuum or low argon pressure backfill, oxygen backfill, and nitrogen backfill. The energy spectra of polyatomic ions are narrower and peaked at lower energies than the atomic ion spectra and decrease in width and average energy with greater ion complexity. The statistical model of polyatomic ion formation does not correctly describe the shape of the energy distributions. The atomic ion energy spectra reveal that more than one ionization mechanism is responsible for the formation of ions from the various elements and that the dominant mechanism is frequently different in the presence of a reactive gas than in a vacuum. Periodic trends of the parameters describing the energy distributions are dependent on the electronic structure of the ions. The average energies of the distributions correlate with the sublimation energies of the pure elements, but the most probable energies do not. Apparent surface binding energies calculated from the energy distributions are presented.     

Sodium resonances in fluorescence from wide-range laser scan in H2-O2-Ar flame

Several resonances and underlying continua were observed in the excitation profiles of sodium atoms in an H₂-O₂-Ar flame, irradiated by the focused beam of a tunable, pulsed dye layer. These profiles are obtained by tuning the laser through the spectral range of Rhodamine 6G and detecting the ensuing fluorescence signals from the 3D-3P and 4D-3P transitions. We observed resonances corresponding to the 3S_{$\text{1}\text{2}$}-3P_{$\text{1}\text{2}$}, 3S_{$\text{1}\text{2}$}-3P_{$\text{3}\text{2}$}, 3P_{$\text{1}\text{2}$}-5S_{$\text{1}\text{2}$}, 3P_{$\text{3}\text{2}$}-5S_{$\text{1}\text{2}$} one-photon transitions and resonances corresponding to the 3S_{$\text{1}\text{2}$}-5S_{$\text{1}\text{2}$}, 3S_{$\text{1}\text{2}$}-4D_{$\text{3}\text{2}$}, _{$\text{5}\text{2}$} two-photon transitions. The observed resonances result from different sequences of radiative and collisional excitation. The presence of the continua is explained by consecutive absorption of laser photons in the collisionally broadened wings of absorption lines. The spatial inhomogeneity of the laser beam and hence of the saturation causes submerging of some resonances into continua.     

Electronic structure of arsabenzene: Microwave spectrum,dipole moment,and nuclear quadrupole coupling constants

The microwave spectrum of arsabenzene was analyzed; a dipole transitions were observed. The following rotational constants were obtained; A = 4871.03 ± 0.18 MHz, B = 2295.87 ± 0.01 MHz, C = 1560.10 ± 0.01 MHz. The dipole moment was 1.10 ± 0.04 D. The nuclear quadrupole coupling constants due to the ⁷⁵As nucleus were χ_aa = ?186.4 ± 0.1 MHz, χ_bb = 43.5 ± 0.2 MHz, χ_cc = 142.9 ± 0.2 MHz, and the asymmetry parameter, η = 0.533 ± 0.002. Analysis of the quadrupole coupling constants indicated that the population of the 4p orbitals on arsenic decrease in the order n_a > n_b > n_c.     

The electronic structure,x-ray photoelectron and emission spectra of YOF

The results of electronic structure calculations for YOF are presented, making use of Xα-DVM together with experimental X-ray photoelectron and emission spectra for this compound. Three versions of calculations have been performed, depending on the relation between oxygen and fluorine charges in the [YO₄F₄] cluster. The interpretation of experimental spectra is carried out on the basis of these calculations.     

Vibration-rotation spectra of CD3CN

Rotational structure in two parallel and five perpendicular bands of CD₃CN is fully analyzed at a resolution of 0.2–0.3 cm^?1. The unresolved contour of the ν₈ fundamental is reproduced by contour simulation and a value of ζ8^z determined. Strong A₁-E Coriolis interactions between the close lying fundamentals ν₃ and ν₆, and ν₄ and ν₇ are interpreted by means of computer contour simulations. Marked localized perturbations in the perpendicular ν₅ and ν₅ + ν₆ bands are analyzed and arise through Fermi resonance interactions, most probably with ν₆ + ν₇ + ν₈ and 2ν₃ + ν₆, respectively. A value of A for the ground state is calculated through use of the rotational data for ν₅, ν₆, ν₅ + ν₆, and customary approximations. In conjunction with the microwave B₀ value, it is consistent with a CD₃ group geometry of $\text{r}{}_0\text{= 1.096}\text{A}\text{?}$, α₀(DCD) = 108° 56′.     

X-Ray photoelectron study of the reaction of water with cerium

The interaction of D₂ O with a polycrystalline cerium surface, successfully cleaned by heavy Ar⁺ bombardment and annealing, was studied at 120 were observed at BE 530.3 (Ce₂O₃) and 532.7eV (adsorbed OD). When clean Ce at 120 K was exposed to D₂ O, the O(1s) spectra were initial eV (adsorbed D₂ O). For exposures greater than 10 Langmuir (L), a multilayer of ice grows and the O(1s) spectra become dominated by a peak at 5The results of interaction with D₂ O are compared with oxidation by O₂. The significant differences are: (1) the absence of Ce(IV) when oxidati relatively small extent of oxidation that occurs when Ce is exposed to D₂ O at 120 K, and (3) the larger chemical-shift of the Ce(III)-derived specThe XPS studies of the interaction of D₂ O with Ce reported here may be summarized as follows:(1) Exposure at 300 K gives rise to O(1s) features characteristic of oxide and hydroxide, while the Ce(3d) spectra indicate Ce(III), but no CE((2) Exposure at 120 K gives O(1s) features characteristic of adsorbed OD, chemisorbed D₂ O, a multilayer of ice, and a small amount of oxide. T are characteristic of clean Ce except for slight broadening.(3) Exposure at 120 K followed by warming to 240 and 300 K gives spectra characteristic of hydroxide and oxide surface-species. Between 240 and 300 K, O(1s) intensity.(4) At 300 K, a relatively thick layer of oxide forms, and after an exposure of 50 L the features characteristic of metallic Ce are no longer observabl(5) As compared to the case for O₂, exposure to D₂ O gives rise to different satellite-splittings in the Ce(3d) spectra, suggesting that di formed in the two cases.(6) The spectra observed for Ce exposed to D₂ O are in excellent accord with those found for the heavier lanthanides [4].     

Photoelectron spectroscopic assignment of the p-states of benzenethiol

He(I) anisotropy parameters and He(I)/He(II) relative band intensities have been determined and utilised to make a complete assignment of the benzenethiol p-electron-region photoelectron spectrum. The major S-atom contribution appears more so in the third band than in the first.     

Structural and electronic properties of binary and ternary platinum oxides

The structural and crystal chemistry of all known binary and ternary platinum oxides are reviewed with emphasis on the types of polyhedral linkage seen and their relationship to electronic properties. Platinum oxides generally fall into two groups: those containing divalent or partially oxidized platinum in planar coordination and those containing fully oxidized tetravalent platinum in octahedral coordination. Highly conducting platinum oxides contain columnar stacks of partially oxidized planar Pt0₄ groups with direct electronic interactions and tend towards chemical non-stoichiometry. The temperature dependence of electrical conductivity in these compounds is related to the dimensionality of the Pt-Pt interaction. Fully oxidized platinum oxides are either semiconductors or insulators, depending on the type of linkage of the octahedral coordination polyhedra and the Pt-Pt distances. The electronic configuration of octahedrally coordinated Pt⁴⁺ (low spin d⁶) precludes the possibility of metallic conductivity in these materials. In general, platinum metal is found to be fairly reactive in air at elevated temperatures, particularly in the presence of alkali and alkaline earth metals. Therefore, caution should be taken before assuming platinum containers or thermocouples are inert with respect to reactants during high temperature synthesis reactions in air or oxidizing conditions.     

Study of the phase transitions in ammonium bromide by Raman spectroscopy

A complete Raman scattering study of an oriented NH₄Br single crystal has been carried out and new results are reported for temperature between 45 to 410°K. The study includes measurements and interpretations of the Raman spectral bandwidths, intensities and frequencies of the lattice and internal modes as a function of temperature. Because of the ability of generating a single domain crystal, unambiguous assignments of the Raman active modes are made. From the present data together with those presented previously significant information on the behavior of the ordering and crystal structure associated with the phase transitions in NH₄Br is obtained.     

Absorption spectrum of carbon dioxide at 4.3 μm

The absorption spectrum of carbon dioxide has been recorded in the wavenumber region 2395-2216 cm^?1 with a spectral resolution between 0.02 and 0.03 cm^?1. About twenty transitions have been identified and the molecular constants of the levels involved have been evaluated. In view of the interest of this region in atmospheric studies a map of the entire spectrum recorded by using a normal sample of carbon dioxide is presented including the identifications for the different bands. About 90% of the lines observed have been interpreted. Some of them have been assigned to transitions originating from higher excited states of ¹²C¹⁶O₂ not considered before in interpreting this spectral region. For the first time, bands of ¹²C¹⁶O¹⁷O have been identified in the 4.3-μm spectra obtained with the natural sample.     

Angle-resolved photoelectron spectroscopy of benzene and hexafluorobenzene as a function of photon energy

Angle-resolved photoelectron spectra of benzene have been recorded using synchrotron radiation as the photon source. From these results the angular dis the first three orbitals; 1e_1g(π), 3e_2g (σ) and 1a_2u(π). Calculations of β employing the MS Xα method have also b and theory for the first two orbitals is excellent. Poor agreement in the core of the third orbital is believed to be due to overlap of the second and has been verified by data obtained for perfluorobenzene. The universality of the energy dependence of β for π orbitals, noted previously for unsatu aromatic systems. The importance of the results for benzene for the future application of angle-resolved photoelectron spectroscopy to complex molecule     

Raman spectroscopy of solid nitrogen up to 374 kbar

We measured the Raman spectrum of room-temperature solid nitrogen in a diamond cell at pressures up to 374 kbar. Only the molecular stretching mode was observed. The frequency of this mode appears to increase smoothly from 2340 cm^-1 at 39 kbar to 2394 cm^-1 at 374 kbar. Between about 50 and 120 kbar, the Raman line is split into a second, higher-frequency peak, which may be associated with molecular ordering in the solid. Measurements of broadening and splitting in fluorescence lines from the ruby pressure gauge indicate that solid nitrogen is reasonably plastic up to 130 kbar. We suggest that nitrogen might serve as a useful pressure medium.     

Mössbauer emission spectroscopy of doped 57Co1−xO—II. donor impurities: 57Co1−xO:Fe,Ti, In

Mossbauer emission studies of Fe, In, and Ti doped ⁵⁷Co_1?xO have been earned out The appearance of the anomalous ferrice line is due to the existence of cationic vacancies and impurity acceptor levels An electron recombination model is proposed which takes into account the electronic character of the impurity defects.     

Characterisation of thin films of bismuth oxide by X-ray photoelectron spectroscopy

The XPS (or ESCA) technique has been used for the characterisation of vacuum-deposited thin films of bismuth oxide. The spectra of Bi metal and Bi₂O₃ powder are used for comparison. The characterisation is carried out by consideration of the positions of the Bi 4f_{$\text{7}\text{2}$} and 4f_{$\text{5}\text{2}$} peaks and by using peak-fitting routines. A lower suboxide of bismuth, and metallic bismuth are observed in bismuth oxide films as evaporated. Oxidation of these films by heating in air results in bismuth(III) oxide. A linear relation is found between the binding energies and oxidation state. The corresponding O 1s spectra for the two types of film are also discussed.     

High resolution electron energy loss spectroscopy of fatty acids prepared by langmuir-blodgett techniques on polycrystalline silver

The surface of monomolecular layers of fatty acids prepared by Langmuir-Blodgett methods on polycrystalline silver has been studied by High Resolution Electron Energy Loss Spectroscopy (HREELS). Results demonstrate HREELS sensitivity to large molecules in molecular organizates on polycrystalline substrates. Spectra are interpreted in comparison with infrared vibrational data; results allow differentiation of degrees of unsaturation. The carbonyl vibration loss is observed as a weak feature, explained as due to the orientation of the fatty acid heads “down” on the subtrate surface approximately 20 Å from the scattering interaction.