Zhang Xun-Sheng

Evidence for Local Interaction of Cs and CO on Ru(0001)

Ultra-violet photoemission spectroscopy measurements for CO adsorption on the (2×2)-Cs precovered Ru (0001) surface were performed. The Cs 5p (5p3/2) level (Cs state) locates at 11.3 eV in binding energy for the (2×2)-Cs overlayer on Ru (0001). Upon the CO adsorption, a new peak, which is associated with the Cs 5p state for the Cs adatoms influenced by the neighbouring CO adsorbed (the Cs+CO state), appears at the lower binding energy side of the Cs state. This new peak is at 10.8 eV for the CO saturation where the (2×2)-Cs+2CO compound layer is formed. This result gives clear evidence for local interaction of Cs and CO on the Ru (0001) surface. PACS: 73. 20. At, 82. 65. My, 68. 35. Bs

Double-Humped Transverse Density Profile in Two-Dimensional Chute Flow with Rough Sidewalls

We study a two-dimensional granular rapid flow with rough sidewalls stuck with the same size discs by molecular dynamics simulation. A transient state of the double-humped density profile in the flowing process has been found, which appears and moves as travelling wave and is the same as the phenomena in the recent experiments [Acta Phys. Sin. 53 (2004) 3389 (in Chinese)]. Our simulation shows that the rough sidewalls play an important role in the converting momentum of boundary discs from the vertical direction to the horizontal one through particle collisions to form this profile and the good elasticity of discs ensures this effect. The appearance of the double-humped profile may be a precursor, which determines if the whole flow will be far repulsed from the boundary and become dilute eventually.