New structures in photoelectric spectra of PbTe

New structures in photoelectric spectra of PbTe, taken with photons in the energy interval between 6.25 and 8.75 eV, have been revealed by measuring the first derivatives of the energy distribution curves. These results are compared with previous measurements and with existing band calculations.     

Geometries,spectra and photoelectric properties of trifluorenylamine-based photoactive layer

The ground-state geometries, electronic structures, spectra and photoelectric properties of two dyes (JA1 and JA2) used for dye-sensitised solar cells (DSSCs) have been investigated with density functional theory (DFT) and time-dependent density functional theory (TDDFT). For simulation of the realistic environment, we calculated the energy levels of molecular orbitals and absorption spectra in solvent, and the different electric fields have been considered. For interpreting the difference of photoelectric properties, we assessed the energy levels and energy gaps of frontier molecular orbitals, electron density, absorption, the total static first hyperpolarisability and driving force of electron injection. The relationship between structure and performance should be established. Furthermore, 24 dyes were designed on the basis of JA1 and JA2 to improve optical response and electron injection. The results of molecular modelling would provide the optional approach for improving performance of photoelectric materials.     

Calculation of angular distribution of multiply scattered ions

A SCAT program is developed for calculation of the angular distribution of multiply scattered ions in the case of various interaction potentials. The accuracy attained is higher than that obtained with the well-known Meyer and Sigmund programs. The influence of the interaction potential on the angular distribution of multiply scattered ions is analyzed. A good agreement between the angular distribution calculated by the SCAT program and the experimental data and the results of simulation by the Monte Carlo method is observed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 103–107, August, 1993.     

Surface sensitivity and angular dependence of X-ray photoelectron spectra

By using an ultra-high vacuum X-ray photoelectron spectrometer designed specifically for surface studies, the surface sensitivity (ratio of surface to volume signal) of the technique was found to be enhanced by approximately one order of magnitude at low angles of electron emission measured from the surface plane. While the $\text{Mo(3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) peak intensity from a clean polycrystalline target of molybdenum was independent of angle, the $\text{Cs(3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) intensity from an adsorbed cesium layer on molybdenum increased and the $\text{Mo(3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) signal from the molybdenum substrate decreased as the angle of emission was decreased. A model is presented to account for the angular dependence and it is proposed that the angular dependence of spectral intensities can be used to differentiate surface from bulk species.     

Zero-field NMR. Calculation of spectra

Zero-field NMR spectra for a number of cases in single crystals and powders are calculated and some factors influencing resolution are discussed.     

The resolution of adjacent spectral lines in the photoelectric recording of Raman spectra

Under the assumption that systematic errors are small, the problem of resolving two lines while scanning a spectrum is discussed. The errors resulting from equipment inertia, from the slit, and from the detector noise are discussed. The relationships determined permit one to choose the slit width of the spectrometer and the time constant of the recording system so that optimum line resolution for various distances between the lines and for various line-width and line-intensity ratios is obtained.     

Decomposition of the angular ESR spectra of fossil tooth enamel fragments

The ESR spectra of a fragment of fossil tooth enamel were measured by rotating it in 10° increments over 360° around its three major axes. We used an automated simulated annealing (SA) procedure for the mathematical decomposition of the spectra. The SA approach is particularly robust in finding global solutions rather than getting stuck in local minima. All angular measurements could be fitted with four Gaussian lines, all of which could be attributed to components of CO₂^? radicals. The results imply that the tooth enamel fragment contains at least two different types of oriented CO₂^? radicals, plus about 9% of non-oriented CO₂^? radicals. The oriented components were tentatively attributed to axial and orthorhombic CO₂^? radicals. Their explicit locations in the crystal domains of the tooth enamel remain unresolved.     

Surface boundary conditions and angular dependence of the spin-wave resonance spectra

General surface boundary conditions with regard to the surface anisotropy energy E_s(iitv, ø) and changes of the static magnetization tM₀ in the presurface region layer have been formulated. On the example of uniaxial surface anosotropy the influence of these factors on the angular dependence of the SWR spectrum is briefly discussed.     

The use of an angular momentum constraint in calculating rotational spectra

A Hartree-Fock method with a constraint on J², the square of the angular momentum, is proposed and applied to simple examples with encouraging results.     

Theoretical study on the photoelectric emission spectra of a field-assisted Au-BaO thin film

The dependence of the spectral distribution of photoelectron emission from gold nano-particles embedded in BaO semiconductor thin film on applied voltage and surface plasmon resonance of gold nano-particles is predicted and investigated theoretically. The photoelectron emission response curves to light wavelength between 0.2 and are given. The dependence of the wavelength threshold on the size of gold nano-particles and external field strength is also shown. The reason that the theoretical photoelectron emission spectra is in the visible region is explained. The probabilities increased for photoexcited electrons to overcome the barrier and escape from the surface are discussed. This could be of importance in designing field-assisted thin film and finding their optimum operation conditions.     

Calculation of Mössbauer reflectometry spectra

Resonant nuclear reflectivity of multilayer structures measured in the specular region as a function of the angle of incidence and Mössbauer velocity (or delay time) contains full depth-selective information on hyperfine interactions. High intensity synchrotron sources may open the way to Mössbauer reflectometry.     

Calculation of the dielectric and Kerr constant angular correlation parameters

The angular correlation parameters G _L involved in the dielectric and Kerr constants are written as averages over the angular pair correlation function. A perturbation theory for these parameters is developed, based on the expansion of Gubbins and Gray for the angular pair correlation function. Numerical calculations are presented showing the influence of polar and quadrupolar forces on these parameters.