TEMPERATURE-DEPENDENCE OF W(100) LEED INTENSITIES

被引:65
作者
HEILMANN, P
HEINZ, K
MULLER, K
机构
[1] Institut für Angewandte Physik, Lehrstuhl für Festkörperphysik der Universität Erlangen-Nümberg, D-8520 Erlangen
关键词
D O I
10.1016/0039-6028(79)90595-8
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The temperature dependence of W(100) LEED intensities has been measured by a very fast television method with automatic thermal diffuse background subtraction for both the (1 × 1) and c(2 × 2) surface structure phases. In contrast to the usual kinematic interpretation the dynamical theory is used to evaluate the surface Debye temperature θs which leads for the high temperature (1 × 1) phase to a value of θs = 210 ± 40 K and for the low temperature c(2 × 2) phase to a value of θs = 400 ± 100 K. The considerable difference is possibly a consequence of a soft phonon. Experimental I(E) curves measured with the same fast method were compared with theoretical spectra calculated with the RFS method. The application of the R-factor formalism leads to 10 ± 2% surface layer contraction in case of the (1 × 1) structure phase. (This value also holds for the c(2 × 2) structure.) The 1 2 1 2 beam half width decreases continuously during the structure phase transition between 350 and 150 K. It indicates a growth of c(2 × 2) domains with decreasing temperature. The average domain size is about 60 Å at 250 K. The corresponding total work function change amounts to 50± 5 meV. © 1979.
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页码:84 / 94
页数:11
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