Energy Dependence of Cu L2,3 Satellites using Synchrotron Excited X-ray Emission Spectroscopy

The L2,3 X-ray emission of Cu metal has been measured using monochromatic synchrotron radiation. The self-absorption effect in the spectra is shown to be very small in our experimental geometry. From the quantitative analysis of spectra recorded at different excitation energies, the L3/L2 emission intensity ratio and the partial Auger-width are extracted. High-energy satellite features on the L3 emission line are separated by a subtraction procedure. The satellite intensity is found to be slowly increasing for excitation energies between the L3, L2 and L1 core-level thresholds due to shake-up and shake-off transitions. As the excitation energy passes the L2 threshold, a step of rapidly increasing satellite intensity of the L3 emission is found due to additional Coster-Kronig processes.Comment: 8 pages, 3 figures, http://link.aps.org/doi/10.1103/PhysRevB.56.1223

X-ray fluorescence spectra of metals excited below threshold

X-ray scattering spectra of Cu and Ni metals have been measured using monochromatic synchrotron radiation tuned from far above to more than 10 eV below threshold. Energy conservation in the scattering process is found to be sufficient to explain the modulation of the spectral shape, neglecting momentum conservation and channel interference. At excitation energies close to and above threshold, the emission spectra map the occupied local partial density of states. For the sub-threshold excitations, the high-energy flank of the inelastic scattering exhibits a Raman-type linear dispersion, and an asymmetric low energy tail develops. For excitation far below threshold the emission spectra are proportional to a convolution of the occupied and unoccuppied local partial densities of states.Comment: 10 pages, 3 figures, http://link.aps.org/doi/10.1103/PhysRevB.68.04511

Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel

The excitation energy dependence of the three-hole satellites in the L3-M4,5M4,5 and L2-M4,5M4,5 Auger spectra of nickel metal has been measured using synchrotron radiation. The satellite behavior in the non-radiative emission spectra at the L3 and L2 thresholds is compared and the influence of the Coster-Kronig channel explored. The three-hole satellite intensity at the L3 Auger emission line reveals a peak structure at 5 eV above the L3 threshold attributed to resonant processes at the 2p53d9 shake-up threshold. This is discussed in connection with the 6-eV feature in the x-ray absorption spectrum.Comment: 8 pages, 4 figures; http://prb.aps.org/abstract/PRB/v58/i7/p3677_

Studies of Solids and Adsorbates in Synchrotron Radiation Excited Soft X-Ray Fluorescence

A progress report is presented on recent developments in soft X-ray emission spectroscopy using synchrotron radiation. Some key experiments are discussed demonstrating that new information can be gained by using synchrotron radiation for this purpose. Recent work on highly resolved soft X-ray emission from monolayers of adsorbed species is commented on and some perspectives are given regarding further developments expected from the third generation sources that are underway

LOCAL ELECTRONIC STRUCTURE IN SIMPLE ALCOHOLS STUDIED IN X-RAY EMISSION

Les spectres d'émission C K de methane, de methanol, d'ethanol et de propanol, et les spectres d'emission O K d'eau, de methanol et d'ethanol, gazeux, excités par l'impact direct des électrons sont analysés sous incidence rasante avec un spectrometre a réseau ayant un rayon de 10 m. Ils ont été interpretés avec l'aide de calcul RHF, le model d'intensté de seul centres, et comparaison de photoemission. Les energies des niveaux K ont été determines et dans les alcools nous avons montré que l'orbital d'oxygen a l'extrémité est fortement melangé avec l'orbital correspondant de carbon.Electron exicted carbon K emission spectra of methane, methanol, ethanol and propanol, and oxygen K emission spectra of water, methanol and ethanol, in the gasphase, have been recorded using a 10 m grazing incidence spectrometer. The spectra are interpreted with the aid of Restricted Hartree Fock calculations, the one-center intensity model, and photoelectron spectra. Coincidences and differences in the spectra of the various molecules are discussed, 1s binding energies are determined and compared to XPS date, and for the alcohols it is shown that the highest occupied oxygen out-of-plane orbitals substantially mix with the corresponding carbon orbitals

Soft x-ray emission spectroscopy using monochromatized synchrotron radiation (invited)

Soft x‐ray emission spectroscopy is a common tool for the study of the electronic structure of molecules and solids. However, the interpretation of spectra is sometimes made difficult by overlaying lines due to satellite transitions or close‐lying core holes. Also, irrelevant inner core transitions may accidentally fall in the wavelength region under study. These problems, which often arise for spectra excited with electrons or broadband photon sources can be removed by using monochromatized synchrotron radiation. In addition, one achieves other advantages as well, such as the ability to study resonant behavior. Another important aspect is the softness of this excitation agent, which allows chemically fragile compounds to be investigated. In this work we demonstrate the feasibility of using monochromatized synchrotron radiation to excite soft x‐ray spectra. We also show new results which have been accomplished as a result of the selectivity of the excitation. The work has been carried out using the Flipper I wiggler beamline at HASYLAB in Hamburg using a new grazing incidence instrument designed specifically for this experiment. The photon flux at the Flipper I station (typically 5×1012 photons per second on the sample with a 1% bandpass) is enough to allow soft x‐ray fluorescence spectra to be recorded at relatively high resolution and within reasonable accumulation times (typically, the spectra presented in this work were recorded in 30 min).The spectrometer is based on a new concept which allows the instrument to be quite small, still covering a large wavelength range (10–250 Å). The basic idea involves the use of several fixed mounted gratings and a large two‐dimensional detector. The grating arrangement provides simple mounting within a limited space and, in particular, large spectral range. The detector can be moved in a three‐axis coordinate system in order to cover the different Rowland curves defined by the different gratings. The arrangement permits the use of gratings with different radii, which further facilitate the achievement of optimum performance over a large range. Two‐dimensional detection is used to allow a large solid angle, without suffering from loss of resolution due to imaging errors. The detector is based on five 2‐in. MCPs with resistive anode read out. The sensitivity of the detector, which is normally very low for soft x rays, especially at grazing angles, is enhanced by CsI coating and by using an entrance electrode