T. Wiell

Local probing of adsorbate electronic structure using soft X-ray emission ; atomic nitrogen on Ni(100) and Cu(100)

Abstract The N 2p partial density of states of p4g-N/Ni(100) and c(2 × 2)-N/Cu(100) overlayers have been studied by soft X-ray emission spectroscopy (SXES) and comparisons with corresponding UV photoelectron spectra are made. Broad states (∼10 eV) are observed due to the hybridisation between the N 2p and the substrate 3d and 4sp bands. For both N/Cu and N/Ni the intensity stretches out to the Fermi level, where a prominent peak for N/Cu is observed. These states close to the Fermi level are interpreted as antibonding 2p-3d hybridised states. The higher occupancy of these states in N/Cu is expected due to the higher binding energy of the 3d band in Cu than in Ni. For a complete interpretation of the SXE spectra, especially for N/Cu where many features are observed, further theoretical studies are required.

A soft X-ray emission study of HFCVD diamond films

Abstract We present carbon K emission spectra of hot filament chemical vapour deposited (HFCVD) diamond films excited with electrons and high-resolution monochromatic undulator radiation. The differences in the band spectra of electron excited films grown under various conditions can be used to characterize the films. The spectrum of natural diamond, excited by synchrotron radiation, exhibits a large dependence on excitation energy. Furthermore, when tuning the excitation beam of the soft X-rays to particular energies, the emission bands of the films show large differences, i.e. differences in the spectra that are small for electron excitation can be enlarged considerably when exciting with tunable synchrotron radiation. A number of other commonly used characterization methods, such as X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy and scanning electron microscopy, were used to compare with the results from the soft X-ray emission study.