Kβ X-ray Spectra Research Articles

Low energy Kβ X-ray satellites of four intermediate Z atoms

Kβ X-ray spectra of four intermediate Z atoms Ge, As, Se and Br generated by photon excitation are analyzed using a wavelength dispersive spectrometer. The energy shifts and relative intensities of low energy Kβ X-ray satellites KMMRAE lines are measured and compared with theoretical estimates wherever available. Supplementing the present results with the reported data, their dependence on atomic number is examined.

High resolution K X-ray spectra of selected silicates induced by MeV proton and carbon micro-beams

Abstract Recently we developed a high resolution wavelength dispersive X-ray spectrometer based on the flat diffraction crystals for use with focused ion beams and used it to study chemical effects in ion beam induced Si K X-ray spectra of silicon and its selected binary compounds. In this work we extended the study to selected silicates. We measured high resolution Si Kα and Kβ X-ray spectra of three silicates: feldspar, kyanite and tourmaline. The spectra have been measured with 2 MeV protons (Kα and Kβ regions) and 20 MeV carbon ions (only Kα region). The results obtained for peak relative intensities were analysed and compared with the related relative intensities obtained from Si, SiC and SiO2.

Statistical distribution based detector response function of a Si(PIN) detector for Kα and Kβ X-ray

A semi-empirical detector response function (DRF) model of a Si (PIN) detector is proposed to fit element Kα and Kβ X-ray spectra, which is based on the statistical distribution analytic (SDA) method. The model for each single peak contains a step function, a Gaussian function, and an exponential tail function. Parameters in the model are obtained by the weighted nonlinear least-squares fitting method. In the application, six kinds of elements' characteristic X-ray spectra are obtained by using the Si (PIN) detector, and fitted by the established DRF model. Reduced chi-square values are at the interval of 1.11–1.25. Other applications of the method are also discussed.

Crossover and valence band Kβ X-rays of chromium oxides

Kβ X-ray spectra of chromium metal and selected chromium oxides were measured twice using medium resolution flat crystal spectrometer and high resolution spectrometer employing Johansson geometry after excitation with 2 MeV proton beams. The positions and intensities of crossover ( Kβ″) and valence ( Kβ 2,5) band X-rays relative to the primary Kβ X-ray components were extracted in a consistent way. The results were compared with the existing data obtained by proton and photon induced ionization mechanisms and theoretical predictions. The obtained results in peak relative positions and intensities were analyzed in order to study dependence on the chromium oxidation states and chromium–oxygen bond lengths in selected chromium oxides. Our results obtained by both spectrometers confirm that the linear trend observed for the valence peak relative energy shift as a function of chromium oxidation number does not depend on the experimental resolution. Experimental results for normalized intensities (i.e. relative intensities divided with the number of chromium–oxygen pairs) of crossover and valence band X-rays obtained by both spectrometers are in very good agreement, and follow exponential relationship with the average Cr―O bond lengths in corresponding chromium oxides. The observed trends in crossover and valence X-rays normalized intensities could be used to measure the average chromium–oxygen bond length in various chromium oxides, with the sum of both crossover and valence X-ray normalized intensities being the most sensitive measure.

DEVELOPMENT OF A TARGET POSITIONING SYSTEM BASED ON A LASER POSITION SENSOR FOR HIGH-EFFICIENCY WAVELENGTH-DISPERSIVE PIXE ANALYSIS

A precise target positioning system based on a laser position sensor was developed for a high-efficiency wavelength dispersive PIXE analysis. The absolute position and the target surface profile were clearly observed using this position sensor, which was rigidly connected to the target vacuum chamber. By using a thin proton beam ( width = 2 mm ) and a small target (width = 1 mm), the optimum target position for the measurement of chlorine ( Cl ) Kβ X-ray could be determined from X-ray detection yields measured at various target positions. We found that the relationship between the X-ray detection yield and the target position can be explained by the target size as well as the incident proton beam width. After precise adjustment of the target position using the above system, target samples with two different Cl compounds, NaCl and NH 4 Cl , were successfully distinguished from the difference in the measured profiles of Kβ X-ray spectra.

Development of a high-efficiency high-resolution particle-induced x-ray emission system for chemical state analysis of environmental samples

We have developed a high-efficiency high-resolution particle-induced x-ray emission (PIXE) system employing a von Hamos-type crystal spectrometer for a chemical state identification of trace elements in environmental samples. The energy resolution of the system was determined to be about 0.05% through the observation of Si Kalpha(1,2) x rays (1.74 keV) from elemental silicon. The throughput efficiency of the system was also evaluated quasitheoretically to be 1.6x10(-7) counts/incident proton for Si Kalpha(1,2) emission. To demonstrate a chemical state analysis using the high-resolution PIXE system, Si Kalpha(1,2) and Kbeta x-ray spectra for SiC, Si(3)N(4), and SiO(2) were measured and compared. The observed chemical shifts of the Si Kalpha(1,2) peaks for SiC, Si(3)N(4), and SiO(2) relative to elemental silicon were 0.20, 0.40, and 0.55 eV, respectively. The tendency of these shifts were well explained by the effective charges of the silicon atoms calculated by a molecular orbital method.

An undergraduate experiment on x-ray spectra and Moseley’s law using a scanning electron microscope

We describe an undergraduate laboratory experiment developed for sophomore modern physics students, using the x-ray analysis feature of a scanning electron microscope. The experiment described is a fundamental physics measurement performed with a state-of-the-art apparatus not usually used in pedagogical physics experiments. The characteristic x-ray spectrum of elements shows a simple progression that can be quantitatively explained by the conceptually important Bohr–Rutherford shell model of atomic structure. Students measure the Kα and Kβ x-ray spectra from metals in the range of 12≤Z≤41. The measurements allow the verification of Moseley’s law scaling of x-ray energies with atomic number and a quantitative measure of the data’s fit to the shell model.

The Kα and Kβ X-ray spectra of Al, Ti, Cr, Fe and Ni induced by 84 MeV nitrogen ions

The K X-rays from the target elements due to N-ion bombardment are measured with a crystal spectrometer. Some aspects owing to high incident energy are discussed. The Kα satellite, Kα hypersatellite and Kβ satellite peak spacings are obtained.

Kβ X-ray emission spectra of Si and SiO2

Kβ X-ray spectra of Si and SiO2 have been measured accurately with a double crystal spectrometer. The measuredKβ spectrum of silicon element was compared with calculations of the electronic density of states.

Solid-state electronic structure effects of silicon Kβ x-ray spectra produced in α-particle excitation

Both Si and SiO2 crystals were bombarded by a 3.2-MeV α-particle beam and the subsequent Si K x-ray yield was measured. The Kα x-ray spectra show fairly close agreement; however, the structure in the Kβ x-ray spectra is quite different for Si and SiO2. These results are interpreted as effects due to the chemical bonding of the oxygen atoms to silicon.

Molecular structure effects of aluminum Kβ x-ray spectra produced in proton and alpha particle excitation

Targets of Al and Al 2O 3 were bombarded by 0.8 MeV protons and 3.2 MeV alpha particles and the subsequent X-ray yield measured. The Kα X-ray spectra of Al and Al 2O 3 show fairly good agreement in both the proton and alpha-induced spectra; however, the structure in the Kβ X-ray spectra deviate from one another in both cases. These results are interpreted as effects due to the chemical bonding of the oxygen atoms to aluminum.