Potential energy curves and dissociation energy of SiCl

The true potential energy curves have been constructed for the ground and excited electronic states of SiCl by the method of Lakshman and Rao. The dissociation energy of the ground state has been estimated by fitting the Hulburt-Hirschfelder function to the true potential energy curves. The dissociation energy thus obtained is 33,500 cm^-1 (4.15 eV), which is in good agreement with the value of 4.5±0.5 eV reported by Gaydon.     

Estimation of dissociation energy of the AsS molecule

Experimental potential energy curve for the X²Π state of AsS has been constructed using the method of Rydberg-Klein-Rees. The precise dissociation energy for the ground state has been estimated as 4.150±0.13 eV by the curve fitting procedure. The first ionization potential of the AsS molecule is found to be 8.66 eV.     

Activation energy of hydrogen in Lu

The impurity induced charge density is calculated in jellium by solving the Schr?dinger equation self-consistently following the procedure of Manninen and Nieminen and using Kohn-Sham density functional formalism. The host-ion contribution is included through the spherical solid model potential (SSMP). The calculated activation energy 0.27 eV is found in good agreement with experimental value 0.28±0.02 eV. The estimated residual resistivity 1.02 μΩ cm/at% for Lu-H system using the resulting phase shifts agrees reasonably well with the observed value 1.75±0.10 μΩ cm/at%. The calculated configurational energy shows that hydrogen prefers tetrahedral(T)-sites over octahedral(O)-sites in Lu matrix. This has been confirmed by Bonnet experimentally. A very shallow value ofs-type bound state of energy −0.00316 Ryd predicts that there is no formation of lutetium hydride solution and H⁺ exists as a free ion in Lu matrix.     

Dissociation energy for the ground state of AlO from true potential energy curve

The true potential energy curve for the ground state of AlO has been extended up to the observed vibrational levels v = 22 using revised vibrational constants. The dissociation energy for the ground state of AlO has been estimated to be 4.15 ± 0.05 eV by the method of curve fitting. The Lippincott potential function has been used for fitting with the RKRV curve.     

Dissociation energy of the ground state of the CuH molecule

The dissociation energy of the ground state of the CuH molecule, which is observed in sun spots and in 19 Piscium, has been evaluated by fitting the Hulburt-Hirschfelder function to the RKRV curve. It is shown that the Hulburt-Hirschfelder potential reproduces the true curve more accurately than does the Loppincott function. The D₀ value obtained in the present study is 2.84eV, while the values reported by Herzberg and Beckel et al. are <2.89 and 2.80 ±0.12eV, respectively.     

Broadening of energy spectra of molecular ion fragments produced by surface small angle scattering

Relative half-widths of energy spectra of molecular hydrogen ions and their fragments scattered by a tungsten surface have been experimentally studied for various primary molecules and their isotopic analogues in the energy range of 100–4000 eV per nucleon. The spectra of fragments turned out to be broader than the spectra of the same particles that are not fragmentation products. The broadening is interpreted within the “explosion” model, i.e., dissociation of a molecular ion due to the change in the shape of the interaction potential of the fragments. The model of “explosive” dissociation of molecules agrees with the data obtained assuming an effective repulsion energy of 1.1 ± 0.1 eV for all molecules.     

Quantum size effect in electron transmission through Cu and Ag films on W(110)

The transmission coefficient of very low energy electrons ( ? 10 eV) normally incident on (111) epitaxial films of Cu and Ag on W(110) is modulated by interference between scattering from the vacuum/metal and metal/metal interfaces. Comparison with calculations of free-electron scattering from a one-dimensional potential model, in which grading of the metal/metal interface is represented by a smoothing of the potential step, indicates that this interface is abrupt within approximately one layer spacing. We obtain a value of 11.0 (8.0) ± 1.0 eV for the inner potential of Cu (Ag) and mean free path lengths of $\text{39 ± 8}\text{A}\text{?}$ at an energy of 7.0 eV relative to the Fermi energy and $\text{29 ± 11}\text{A}\text{?}$ at 9.0 eV for Cu, and $\text{25 ± 10}\text{A}\text{?}$ at 7.5 eV for Ag. Work function values are obtained by the field emission retarding potential technique. We investigate the effects of the surface potential barrier, inelastic scattering and surface roughness, and evaluate the validity of the one-dimensional model presented.     

Low energy electron attenuation length studies in thin amorphous carbon films

The results of experiments on low energy electrons passing through thin amorphous carbon films are reported. For electron energies between 50 and 3000 eV, electron attenuation lengths were determined by electron transmission measurements through carbon films of thicknesses between 81 and 210 Å. The density of these amorphous carbon films was also obtained by a sink—float method and found to be 1.90 ± 0.05 g cm^?3. The electron attenuation length for inelastic scattering was found to increase monotonically from approximately 10 to 55 Å over the 50 to 3000 eV range. Over the 500–3000 eV energy region, the results are in good agreement with mean free paths calculated using optically measured dielectric functions.     

Determination of the vacancy formation energy for different sublattices of ordered β-CuZn alloy by positron annihilation method

The temperature dependence of positron annihilation has been investigated for samples of the ordered β-CuZn alloy with different crystallographic orientations. The results obtained have been interpreted on the basis of the extended trapping model. Analysis of the temperature dependence of the peak coincidence count gives the values of the free energy of formation for vacant sites, left by Cu- and Zn atoms equal 0.58±0.02 eV and 0.77±0.04 eV, respectively. The dependence of the vacancy formation energy on the long-range order parameter has not been observed.     

Surface-state parameters from very low energy electron reflection data

A parametric form of the amplitude of elastic reflection of very low energy electrons is derived. The amplitude expression conforms to the results of an earlier analysis of a simple case of electron reflection called the quasi two-beam case. The parameters in the amplitude expression refer to: (1) the surface states of the crystal; (2) the band structure of the substrate crystal; and (3) absorption (inelastic scattering) in the energy range of the experiment The amplitude expression also includes parameters relating to (4) the behavior of the amplitude at infinity and at negative energy.The amplitude expression is used to parameterize existing experimental results for nickel (001) and for the surface formed by adsorption of sodium on nickel (001) to form the centered (2 × 2) structure. The parameterization employs previously-computed values of parameters relating to the nickel band structure [category (2) above], and parameters in categories (1), (3) and (4) are adjusted to fit the electron-reflection data. In the case of the sodium-covered surface it is shown that the shape of the intensity-energy curve and the general level of intensity relative to that for clean nickel depends critically on the surface-state parameters. Two surface states are needed to fit the intensity data The values of the surface-state parameters are: location relative to vacuum level: 2.5 ± 0.1, 6.9 ± 0.2eV; width: 4.2 ± 0.4, 7.5 ± 1.0eV. The classification and significance of surface-state resonances is discussed briefly.     

Electronic structure and Coulomb correlation energy in UO2 single crystal

High-resolution X-Ray Photoemission Spectroscopy (XPS) and Bremsstrahlung Isochromat Spectroscopy (BIS) measurements are reported for UO₂. Clear evidence is found for the localization of the 5f electrons. The Coulomb correlation energy and the p-d gap are determined to be 4.6 ± 0.8 and 5.0 ± 0.4 eV, respectively. A satellite observed 7 eV below the Uranium core levels is assigned to a final state excitation from the valence p band to the empty 5f³ state.     

Direct evidence for a very low atom displacement threshold energy around the 〈110〉 directions in copper

The dependence of the displacement cross section of Cu on electron energy and crystal orientation has very accurately been determined by high-voltage electron microscopy. The minimum displacement threshold energy of (9.5 ± 0.5) eV occurs at an angle of 10° from 〈110〉 directions.     

Chlorine adsorption on copper: III. Angle-resolved electron energy loss spectroscopy

Electronic excitations on Cu(001) and Cu(001)c(2 × 2)-Cl have been investigated by angle-resolved electron energy loss spectroscopy at an angular resolution of Δθ = ±1° and an energy resolution of ΔE = 60 meV. Primary energies in the 50–100 eV range were chosen and the specular reflection was studied for angles 35° ? θ ? 71° with respect to the surface normal. The results are summarized as follows: The specular Cu(001) spectra are compared to optical data and good agreement is found for the energetic position of direct transitions. The electronic losses observed for the ordered overlayer system may be interpreted by one-electron excitations from occupied surface bands (known from angle-resolved photoemission results) into an empty band with a minimum energy at 0.4 eV above the Fermi level.     

The elastic scattering of low energy electrons from Xenon

Calculations are presented of angular distributions for electrons elastically scattered from xenon in the energy range 5.5 to 10 eV. The potential describing the xenon atom is determined by the X_α-approximation. The relative dependence with energy of the differential cross section at 30° scattering angle has been calculated in the range 30 to 200 eV. The theoretical results are in very good agreement with experimental data.     

A shock tube determination of the CN ground state dissociation energy and the CN violet electronic transition moment

The CN ground state (X²∑⁺) dissociation energy and the electronic transition moment of the CN violet B²∑⁺ ? X²∑⁺ bands have been simultaneously determined from spectral emission measurements behind incident shock waves. The unshocked test gases were composed of various CO₂-CO-N₂-Ar mixtures, and the temperatures behind the incident shocks ranged from 3500 to 8000°K. The dissociation energy was determined to be 7.89 eV with a statistical precision of ±0.02 eV; a conservative estimate of the absolute error was ±0.13 eV. The value obtained for the Δυ = 0 sequence electronic transition moment was 0.90 ± 0.14, corresponding to an electronic absorption f-number of 0.035 ± 0.005 at a wavelength of 3860 Å. The electronic transition moment variation with internuclear separation was also measured.     

Elektronenpolarisation im Energiebereich unterhalb 50 eV durch Streuung an freien Hg-Atomen

The angular dependence of spin polarizationP(Θ) of electrons elastically scattered by a beam of mercury atoms is measured in a double scattering experiment for electron energies of 45±1 eV; 23±1 eV; 7±1 eV; and 3,5±1 eV. Maximum degree of polarization obtained isP(100°)=0,39±0,07; electron energy 7±1 eV; electron current 10^?12–10^?11 A.     

Photoluminescence measurements of the 1.55 eV band of Ge doped AℓxGa1−xAs

The photoluminescence of the 1.55 eV band of Ge doped A?_xGa_1?xAs, with x=0.30–0.33, grown by liquid phase epitaxy is presented. The broad shape was found to be due to a lattice relaxation upon optical transitions. Resonant modes with ?ω_q = 35±2 meV and ?ω_q = 45±2 meV are found for the optical band, yielding a zero phonon transition energy = 1.73±0.02 eV and a Franck-Condon shift = 0.17–0.20 eV for the optical center. The activation energy of thermal quenching yields an associated donnor binding energy of 0.17±0.04 eV. Possible mechanisms for the radiative transitions are discussed.     

Dissociation energies of SO+, SF and PBr

Experimental potential energy curves for the electronic ground states of SO⁺, SF and PBr have been constructed by using the methods of Rydberg-Klein-Rees, as modified by Vanderslice et al., as well as the authors' modification of the method of Vaidyan and Santaram. The dissociation energies of the ground states have been obtained by a curve fitting procedure using an empirical potential function with the RKRV potential energy curves. The estimated values of the dissociation energies are 5.43 ± 0.19, 3.30 ± 0.10 and 4.46 ± 0.14 eV for SO⁺, SF and PBr, respectively.     

Reevaluation of bandgap and free exciton binding energy of GaP

Very sensitive measurements on the spectral behaviour of the free-to-bound excitation σ_pl^°(hν) from the valence band to the deep 0 donor in GaP at low temperatures are presented. Evaluation of the threshold energy for the electronic transition, together with the known value of the 0 binding energy, provides a simple and accurate way to determine the indirect bandgap E_g of GaP. Our new value is E_g = 2.3525 ± 0.003 eV at 1.5 K, which gives an exciton binding energy E_x = 24 ± 3 meV, considerably larger than previously used values. These data also imply an upward revision of acceptor binding energies in GaP with 10 ± 2 meV.     

Ionization energy of acetone by vacuum ultraviolet mass-analyzed threshold ionization spectrometry

Mass-analyzed threshold ionization (MATI) time-of-flight mass spectrometer using coherent vacuum ultraviolet (VUV) laser generated by four-wave difference frequency mixing (FWDFM) in Kr has been constructed and utilized to obtain the accurate ionization energy of acetone. From the MATI onsets measured from various applied pulsed fields, the ionization energy to the ionic ground state of acetone has been determined to be 9.7074 ± 0.0019 eV.