Phonon modes at the 2H-NbSe2 surface observed by grazing incidence inelastic x-ray scattering |
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Authors: | Murphy B M Requardt H Stettner J Serrano J Krisch M Müller M Press W |
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Institution: | Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universit?t, D-24098 Kiel, Germany. |
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Abstract: | We have determined the dispersion of acoustic and optical surface phonon modes 2H-NbSe2 at the by inelastic x-ray scattering under grazing incidence conditions. Already, at room temperature, an anomaly is observed close to the charge density wave -vector position located at about one-third along the Gamma-M direction of the Brillouin zone. Our results indicate that the anomaly for the surface mode occurs at a lower energy than that measured in bulk sensitive geometry in the same experiment, showing evidence of a modified behavior in the uppermost layers. We demonstrate that inelastic x-ray scattering in grazing incidence conditions provides a unique tool to selectively study either surface or bulk lattice dynamics in a single experiment. |
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