N. P. Tucker

Photoemission Study of CO Adsorption on Gd

Angle-resolved UV photoemission spectroscopy has been used to investigate the interaction of CO with Gd films, grown on W(110). The results suggest the CO absorbs dissociatively, initially forming Gd(2)O(3), with subsequent catalytic oxidation of CO to form carbonate.

Core-level spectroscopy study of rare-earth metal/W(110) interface formation

The electronic structure of rare-earth metal/W(110) interfaces during the initial stages of deposition has been investigated using core-level shift spectroscopy. Three rare-earth metals (Gd, Y and Yb) have been grown on a W(110) substrate. Shifts in the W core level peaks of > 300 meV have been confirmed for the clean W(110) surface. On completion of each interface a bulk feature and only one shifted peak is observed which supports evidence that no alloying occurs. At submonolayer coverages an additional feature is seen at higher kinetic energies which is attributed to emission from W atoms under various adsorbate structures.

Gd/W(110) interface formation studied by w 4f surface core-level spectroscopy.

W 4f core-level spectra of Gd films on W(110) show components which can be identified as being due to bulk and interface W. The results suggest that the W/Gd interface is abrupt, i.e. no interface alloying occurs. At submonolayer coverages a further component is seen which is attributable to intermediate (n x 2) phases.

Utilization of Photoemission Cross-Section Effects for Monitoring Thin-Film Growth in UHV.

Given the tunability of synchrotron radiation, photoemission spectroscopy can be used to monitor the growth modes of thin films in UHV. Cross-section effects such as Cooper minima and resonant photoemission can be exploited to maximize the adsorbate signal and minimize that from the substrate. Under favourable circumstances growth can be monitored in real time at coverages of <1%. As an example the growth of Gd on W(110) is investigated.

Dichroism in constant final-state photoemission for Gd(0 0 0 1) 4d-4f giant resonance

Abstract The dichroism in constant final state photoemission for the 4d–4f giant resonance and its pre-edge structure is studied from thin epitaxial gadolinium films. This study provides information of the maximum magnetic linear dichroism in angular dependence (MLDAD) effect which can be seen for certain photon energies. The MLDAD results can be compared with the magnetic circular dichroism on the same Gd films grown on W(1 1 0). These are clear differences between these two techniques at the main resonance.

Magnetic linear dichroism effects in the Gd 5p photoemission peaks

Abstract Magnetic linear dichroism has been studied to investigate the Gd 5p photoemission peaks. The Gd 5p components have been labelled according to an L–S coupling determination of the possible final states that can be reached from the 8 S 7/2 initial state. These results show two triplet states. The behaviour of the 5p peaks through the giant resonance has been also studied. The 5p1/2 peaks show a more prominent resonant behaviour than the 5p3/2 peaks.

Magnetic linear dichroism in gadolinium 4f satellites

Thin films of gadolinium, 60 monolayers thick, have been grown on a W (1 1 0) substrate and resonant behaviour of the 4f satellite peaks has been studied with magnetic linear dichroism in angular dependence (MLDAD). The 4f satellite peaks occur for the pre-edge and resonant energies, and are best developed for the peak and shoulder closest to the main resonance in photoadsorption spectra. MLDAD spectra across the giant resonance and its pre-edge structure of the Gd 4f satellite peaks indicates that the greatest intensities occurred for photon energies around the photoadsorption peak immediately before the main resonance. No dichroism effect was observed in the satellites. The direct photoemission and autoionisation resonant photoemission make no contribution to the satellite peaks.