XAFS spectra from X-ray fluorescence Kβ line using conventional energy-discriminating detector

X-ray fluorescence spectra of copper (Cu) metal, copper monoxide (CuO), and potassium chromate (K₂CrO₄) were recorded as a function of incident X-ray energy near the Cu K-edge and chromium (Cr) K-edge, respectively, using a conventional silicon drift detector. The spectra contained components due to elastic, inelastic, and multiple scattering, in addition to the Kα and Kβ lines. Cu and Cr K-edge X-ray absorption fine structure (XAFS) spectra of Cu, CuO, and K₂CrO₄ were obtained by an intensity analysis of the Kα and Kβ lines. The intensity of the Kβ line for the different incident photon energies was obtained by numerically removing the additional scattering components using the MUSCAT program. These spectra exhibited a jump near the K absorption edges, which reproduced the spectral features obtained in transmission mode for both Cu, CuO, and K₂CrO₄. A chemical shift was also clearly identified in the X-ray absorption near edges structure using the X-ray fluorescence Kβ line. In addition, the Cr K-edge extended XAFS spectrum of K₂CrO₄ was clearly observed using the Cr Kβ fluorescent line. The XAFS measurements on the Kα and Kβ lines are possible, and they carry equally valuable information.     

X-ray photoelectron spectroscopy characterization of the layered intercalated compound K2xMn1 − xPS3

Polycrystalline powders of the layered MnPS₃ compound have been intercalated with K⁺ ions by ion-exchange to yield the K_2xMn_1 − xPS₃ intercalate. X-ray photoelectron spectroscopy has been applied to learn about the electronic structure of this compound. In particular, we have studied the XPS spectra of the Mn 2p and 3p, P and S 2p, K 2p and 3p core levels and of the valence band region. The binding energies for various core levels of the elements present in this compound and their observed chemical shifts are analyzed. The data give evidence for the lack of non-equivalent atoms of K, Mn, P and S. Shake-up satellites are present at the Mn 2p and 3p core levels. The occurrence of such lines allows us to hypothesize that K_2xMn_1 − xPS₃ is a large-gap insulating Mn compound. Confirmation that only an ion transfer accompanies the intercalation process is given from both the strong observed similarity with the corresponding XPS spectra in MnPS₃ and the observed binding energy positions of the K 2p and 3p levels. As regards the valence band XPS spectrum, the observed analogies with the corresponding XPS spectra of the pure compound and of other K compounds have allowed us to single out two regions and their probable contributors.     

Kα X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K_α satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of K_αL¹/K_αL⁰ relative intensities are compared with values obtained by electron excitation.      

Electron mean free paths as a function of kinetic energy: A substrate overlayer investigation of polyparaxylylene films on gold using A Ti Kα X-ray source

Using the substrate overlayer technique with a Ti Kα_1,2 X-ray source (hν = 4510 eV) electron mean free paths λ have been determined for in situ deposited polyparaxylylene films. By monitoring the attenuation of signals arising from the substrate Au 4f, 4d, 4p, 3d and 3p core levels excited by the Ti Kα X-ray source and for the Au 4f and 4d levels excited by Cu Lα X-rays (hν = 929.7 eV) mean free paths have been determined in the kinetic energy range ～443–～59O eV. The present results are compared with those reported previously for lower kinetic energies using Mg Kα_1,2 and Al Kα_1,2 photon sources. The results indicate that at kinetic energies of ～4000 eV the typical sampling depth using a Ti Kα source is ～ 150 Å.     

Observation of plasmon excitations in X-ray production following heavy ion bombardment

Four equidistant peaks are observed below the Kα_1,2 line in the X-ray spectra of Na, Al, Si, SiO₂, Ca, Sc and Ti, produced by oxygen bombardment. With much weaker intensity, these lines are also seen in proton excitation. The lines are interpreted to be due to the excitation of one or more volume plasmons in the target material by the Kα_1,2 X-ray decay.     

Chemical effects on beryllium K X-ray spectra produced by heavy ion bombardment

Beryllium X-ray spectra from Be and BeO targets by proton, helium, nitrogen and argon ion bombardment have been measured. In the oxide, chemical shifts of K_α and K²_α X-ray lines are similar magnitude and the intense satellite KL and hypersatellite K²L lines are observed by heavy ion bombardment.     

Study of the electronic structure of M(CO)5Cl complexes (M = Mn, Re) using X-ray spectroscopy and density-functional theory

The electronic structure of M(CO)₅Cl metal complexes (M = Mn, Re) has been investigated by X-ray emission spectroscopy. The obtained X-ray emission C Kα, OKα, Cl Kβ₁, MnLα, and MnKβ₅ spectra for Mn(CO)₅Cl and ReLβ₅ spectra for Re(CO)₅Cl have been interpreted on the basis of the quantum-mechanical calculations by the method of density-functional theory, using the Gaussian-98 program. The investigation of Mn(CO)₅Cl and Re(CO)₅Cl showed similarity of the electronic structure of both complexes. Only small differences have been revealed in the energy structure and orbital occupancies of the atomic orbitals of the corresponding molecular orbitals; these differences are caused by the difference of the type of metal ions and the molecule geometry. On the basis of the performed quantum-mechanical calculations, theoretical X-ray emission spectra have been constructed, which reproduce well the characteristic features of the corresponding experimental spectra of M(CO)₅Cl metal complexes (M = Mn, Re).     

Energy shifts versus projectile Z for Ti Kα X ray and satellites

A high resolution study of Ti Kα X-ray spectra versus projectile Z has been performed. Energy shifts and width changes were observed in both the diagram and satellite lines. These effects are explained as multiple ionization of the M shell.     

Laser spectroscopy of NO2 under very high resolution: Fluorescence spectra from selectively excited hfs levels

Absorption spectra of NO₂ with reduced Doppler width and resolved hyperfine structure have been obtained by crossing the beam from a single mode argon laser, tunable around 4880 and 5145 Å, with a well-collimated NO₂ beam at low pressures. With the laser frequency stabilized onto selected NO₂ absorption lines the fluorescence spectra of NO₂ molecules in selectively populated hfs levels of an excited electronic state were examined through a grating monochromator which resolved the different rotational lines. From the fluorescence spectra the quantum numbers N′ and K′ of the emitting levels could be determined. The analysis proved that some emitting levels have K′-values differing from that of the primarily excited level. This implies radiationless transitions between different electronic states in the free molecule, which can change the value of K′ but preserve that of N′.     

X-ray spectroscopy in the EC nucleus

The probabilities P_KK of double K-shell vacancy production per K electron capture decay and per K internal conversion of ¹⁰⁹Cd and ²⁰⁷Bi have been determined by means of the double- and triple-coincidence experiments using Kα X-ray and K internal conversion. For ¹⁰⁹Cd we find P_KK(EC) = (4.2 ± 0.5) × 10⁻⁵ and P_KK(IC) = (4.32 ± 0.46) × 10⁻⁵, and for ²⁰⁷Bi, P_KK(EC) = (2.54 ± 0.50) × 10⁻⁵. The observed X-ray energy shifts of the hypersatellite Ag (Kα₁^H) X-ray and the hypersatellite Pb (Kα₁^H) X-ray lines are 545±15 eV and 1238±45 eV, respectively.     

DasK-Röntgenemissionsspektrum des Chlors in freien Molekülen

TheKα andKβ spectra of chlorine in free molecules were studied using a special fluorescence X-ray tube and a high resolving curved crystal spectrograph with photoelectric registration. It was found that the wavelength shifts of ClKα₁ obtained for various gaseous compounds do not show the regularities observed with solid compounds of other 3rd period elements. — TheKβ spectrum consists of discrete lines the most intense of which result from transitions of the lonely pair electrons of the chlorine atoms. The spectra of HCl, Cl₂ and CH₃Cl can be explained using optical and betaspectroscopical data and MO calculations. The general structure of ClKβ of organic compounds seems to be determined by the hybridisation type of the carbon atoms bound to the chlorine atoms. Evidence is found for a contribution of molecular vibrational energy to the energies of the X-ray transitions.     

VK centers in RbCaF3: Lattice distortion in the tetragonal phase

Intrinsic V_K centers have been produced in single domain RbCaF₃ crystals by irradiation at 77 K. The twisting of the CaF₆ octahedra about the tetragonal axis as a result of the 196 K phase change is readily detected in the V_K center EPR spectra. Analysis of these spectra required dividing the six distinct V_K center sites on a given octahedron into two classes and determining the spin Hamiltonian parameters independently for each class.     

X-ray emission spectra and electronic structure of VO,VN, VC

The experimental K_β5 and L_α emission spectra for vanadium and K_α spectra for nonmetal are studied for vanadium monoxide, nitride and carbide. Using the spectra unfolding the experimental molecular orbital diagrams have been obtained. By the semiempirical Mulliken-Wolfsberg-Helmholz method with the self-consistency on charges and configurations the calculations of electronic structure of clusters [VO₆]^10?, [VN₆]^15? and [VC₆]^20? have been carried out. The results of calculations are compared with the X-ray data. The effects of chemical bonding and charge densities on metal atoms in VO, VN, VC are discussed.     

A complete and self-consistent evaluation of XPS spectra of TiN

The electron configuration in single crystalline (sc-)titanium nitride (TiN) has been quantitatively studied using angle resolved X-ray photoelectron spectroscopy (AR-XPS). All samples were fabricated and transferred in situ so that only minimal surface contaminations were observed. The residual oxygen contamination was separated from the bulk information by extrapolating angle resolved measurements. Special attention is given to the quantitative evaluation of the spectra based on basic principles. Shake-up features are observed on core level lines and appear due two final ionized states. The ratio of this shake-up and the main Ti 2p energy line are investigated in this paper. In order to quantify this shake-up a precise evaluation is required. Here we present an approach to evaluate the XPS spectra of the Ti 2p photoemission line in TiN in a self-consistent manner that accounts for all features observable in an energy window of 80 eV. The evaluation considers the appropriate Tougaard background correction, shake-up features as well as surface and bulk plasmons. The ratio of the Ti 2p_1/2 and Ti 2p_3/2 and the corresponding peaks in the energy loss features fulfill the requirements given by quantum mechanics. The energy loss ΔE due to the shake-up process and the shake-up ratio have been determined quantitatively for oxygen-free bulk titanium nitride. The origin of the shake-up, its intensity and energy difference ΔE are explained by a two electron excitation process.     

Far infrared laser magnetic resonance spectra of the ClSO and FSO radicals in the gas phase

The detection of the free radicals ClSO and FSO by the technique of far infrared laser magnetic resonance is reported. Observations of the former have been made with several laser lines; the spectra are complicated and have not been assigned but are attributed to ClSO on the basis of several chemical tests. The FSO radical was generated by the reaction of carbon disulphide with the products of a discharge through CF₄ + O₂. Spectra have been observed with laser lines at 394, 419 and 513 μm. Using the results of a subsequent microwave study of FSO, the rotational transitions involved in these spectra have been identified. The spectrum at 513 μm has been studied in detail and is shown to arise through level anticrossings between the levels 14_5,Kc (the lower levels involved in the transition) and 15_4,Kc+2. All aspects of this spectrum are reproduced quantitatively by the parameters determined from the microwave spectrum. It is thought that the other two FSO spectra arise in a similar manner. Such anticrossing signals are likely to be widespread in LMR experiments, causing intense narrow lines to occur at high magnetic fields even for molecules with weakly coupled electron spin.     

High-resolution infrared spectrum and analysis of the ν1 band of CF337Cl

The rotational structure of CF₃³⁷Cl ν₁ band has been investigated using spectra of trifluorochloromethane in natural isotopic abundance, recorded with a tunable diode laser spectrometer. The spectra analyzed have been obtained by keeping the sample at low temperature (～200 K) to minimize the strong interference arising from “hot” band transitions. The K structure of many P(J) and R(J) multiplets has been resolved and positively identified: the maximum J value reached in the P and R branches was 38 and 40, respectively. About 650 unblended lines have been used for the least-squares fit to the energy expression including the quartic centrifugal distortion coefficients. Molecular constants for the ν₁ band of CF₃³⁷Cl have been derived. A weak perturbation affecting the rotational levels with K = 18 and J′ ≥ 36 has also been observed.     

Structural, magnetic and electronic structure studies of Mn doped TiO2 thin films

We report structural, magnetic and electronic structure study of Mn doped TiO₂ thin films grown using pulsed laser deposition method. The films were characterized using X-ray diffraction (XRD), dc magnetization, X-ray magnetic circular dichroism (XMCD) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements. XRD results indicate that films exhibit single phase nature with rutile structure and exclude the secondary phase related to Mn metal cluster or any oxide phase of Mn. Magnetization studies reveal that both the films (3% and 5% Mn doped TiO₂) exhibit room temperature ferromagnetism and saturation magnetization increases with increase in concentration of Mn doping. The spectral features of XMCD at Mn L_3,2 edge show that Mn²⁺ ions contribute to the ferromagnetism. NEXAFS spectra measured at O K edge show a strong hybridization between Mn, Ti 3d and O 2p orbitals. NEXAFS spectra measured at Mn and Ti L_3,2 edge show that Mn exist in +2 valence state, whereas, Ti is in +4 state in Mn doped TiO₂ films.     

X-Ray spectral and theoretical investigations of the electronic structure of phenylcyclosilanes (SiPh2) n (n = 4–6)

The X-ray emission SiKα_{1, 2} and SiKβ₁ spectra of a series of phenylcyclosilanes (SiPh₂) _n (n = 4–6) have been obtained. Using the results of quantum-chemical calculations in the density functional theory approximation, the fine structure of SiKβ₁ spectra has been interpreted. Distributions of densities of electron states of silicon atoms over the valence band have been constructed and the types of chemical bonds providing the Si-Si and Si-Ph interactions have been established. Based on the theory of natural bond orbitals, the chemical bonding in the studied series of phenylcyclosilanes has been analyzed.     

Theoretical and experimental study of the electronic structure of tin dioxide

The electronic structure of tin dioxide has been theoretically studied within the linearized augmented plane wave method using the Wien2k program package. The total and local partial electron densities of states have been calculated. The X-ray emission K-spectrum of oxygen has been calculated. The X-ray absorption spectra of the tin M _4,5-edge and oxygen K-edge have been calculated by simulating the supercell and core hole. The calculated results have been compared with the experimental data obtained using synchrotron radiation.     

X-ray absorption spectra: K-edges of 3d transition metals,L-edges of 3d and 4d metals,and M-edges of palladium

The X-ray absorption spectra of the 3d and 4d transition metals have been calculated within the single-particle approximation by a new linearized augmented plane wave method. The spectra, calculated with sharp atomic and band-structure single-particle levels, have been convoluted with a Lorentzian broadening function whose width is the sum of that of the core hole and the excited electrons. Plots are shown for (i) the K-edge fine structures up to at least 100 eV above the edge for Ca, Ti, Cr, Co, Cu, and Zn, (ii) the L_{2, 3} white lines for Ca, Ti, Cr, Co, and Cu, (iii) the L₃ white lines for Sr, Zr, Nb, Ru, Rh, and Pd, and (iv) the M_{2, 3} and M_4,5 spectrum of Pd. Systematic features which depend on the crystal structure and the placement of the Fermi level with conduction band are briefly discussed.