Variation Of Peak Position Research Articles

A Statistical Analysis of X-ray Stress Measurement by the Gaussian Curve-Fitting Method

Abstract Simplified equations for calculating peak position and its standard deviation caused by counting statistics, which is a fundamental source of scatter in X-ray stress measurement, are derived for the Gaussian curve-fitting method. These equations when used with an inexpensive microcomputer will facilitate a precise and rapid residual stress determination. The time required for calculating the peak position and its standard deviation with such a microcomputer is only 0.9 s. The residual stress in a hardened structural steel, Type JIS S45C, was measured. The standard deviation in the stress as measured by the Gaussian curve method was smaller than that by the parabola method, which until now has been the most widely used technique. The variation in peak position in the Gaussian curve method with the various selections of data points used in the calculation is also smaller than that in the parabola method. Since the correction for background has little influence on the results, it can be omitted to reduce the measurement time.

Peak position variation with source geometry in Ge(Li) detector spectra

Shifts in the apparent energy of peaks in gamma-ray spectra from Ge(Li) detectors have been measured as a function of the source-detector geometry for several detectors. For a planar detector, the change in the apparent peak energy was measured between gamma rays entering parallel and perpendicular to the electric field. With a bias of was observed for a 2500 keV gamma ray. For a planar and five coaxial detectors, the shift in peak energy was measured as a function of the source-detector distance. For a gamma ray of 1500 keV, the shifts were from >100 eV to −90 eV for the six detectors in going from a source-detector distance of 35 cm to 1 cm. The larger of these shifts could introduce significant systematic errors in precise gamma-ray energy difference measurements. This effect is presumed to result from (1) the acceleration of electrons due to the detector bias and (2) variation in the charge collection efficiency over the detector volume.

Interpretation of ultraviolet photoelectron spectra by simplified methods

Simplified procedures for the interpretation of ultraviolet photoelectron spectra are surveyed and discussed. It is argued that peaks may be associated with identifiable orbitals and that variations in peak position and shape may be explained by consideration of charge density within a molecule and intramolecular orbital interactions. It is shown that partial charges as well as electronegativity, Taft σ * functions and other empirical measures of electronic distribution can be correlated with ionization energies in ultraviolet photoelectron spectra. Consideration of band energies, site symmetry and peak intensity helps in the interpretation. Correlation diagrams can be used to facilitate identification if the spectra have been previously recorded.

Electroabsorption of CdS and CdSe Single Crystals in the Exciton Region

AbstractElectroabsorption spectra in the exciton region were measured on very thin CdS and CdSe single crystals at 77 °K in the field range 1 × 103 to 2.4 × 104 V/cm for both polarizations of incident light with respect to the c‐axis. The electroabsorption spectra exhibit much more details than electroreflection spectra know so far. The variation of peak positions and peak heights with electric field strength is different for different parts of the spectrum. Some of the peaks shift to lower and others o higher energies with increasing field strength. The spectra can be interpreted in terms of a second order Stark shift, field induced line broadening and Franz‐Keldysh type interband oscillations.

Use of x-ray emission spectroscopy in the characterization of thin films of aluminum oxides and hydroxides

X-ray emission bands (AlK β) of several aluminum oxides and hydroxides have been compared. The bands from the oxyhydroxides and γ-Al 2O 3 are single peaks with some variations in peak position from material to material. However, the band from α-Al 2O 3 is much broader and forms a distinct doublet. The bands from the oxyhydroxides occur at shorter wavelengths than the peaks from α-Al 2O 3. These results may be used to aid in the characterization of thin films (crystalline as well as non-crystalline) on aluminum and aluminum alloys.