Surface structure of single-crystal MoS{sub 2}(0002) and Cs/MoS{sub 2}(0002) by X-ray photoelectron diffraction
- Lehigh Univ., Bethlehem, PA (United States)
The surface structure of a clean MoS{sub 2}(0002) and an in situ Cs surface-doped MoS{sub 2}(0002) has been studied using high-resolution X-ray photoemission spectroscopy. The X-ray photoelectron diffraction (XPD) patterns of the Mo 3d{sub 5/2} and S 2p core levels from a clean, well-ordered MoS{sub 2}(0002) show forward focusing intensity maxima along the directions of nearest neighbors in MoS{sub 2} in both the polar and azimuthal angle scans. The XPD patterns in the azimuthal angle scan exhibit a pronounced photoelectron intensity maximum at every 60{degree}, reflecting the 6-fold rotational symmetry of the basal plane. In addition, because of the finite electron escape depth and the short-range order of the scattered photoelectrons, the azimuthal scans of both the Mo 3d{sub 5/2} and the S 2p core levels further display the 3-fold rotational symmetry of the trigonal prismatic local structure, which MoS{sub 2}(0002) possesses. The deposition of Cs onto the MoS{sub 2}(0002) surface at room temperature did not introduce any significant changes either in the low-energy electron diffraction or in the XPD patterns, indicating the absence of Cs-induced surface relaxation, but a new photoemission was observed 1.6 e V above the valence band edge of MoS{sub 2}, which corresponds to the Cs 6s photoelectron shared with the MoS{sub 2} lattice. Thus Cs/MoS{sub 2} represents an electron donor-acceptor (EDA) surface complex. 32 refs., 10 figs.
- OSTI ID:
- 374469
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 25 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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