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ÉNöµCYbúËõ March 2011 Vol.24 No.2  109(C) 2011 The Japanese Society for Synchrotron Radiation ResearchFig. 1The Yb 3d core­level spectra for YbS and Yb metal recordedat the emission angles u0and 80
, in comparison with that). Each inset shows the u dependence ofof YbCu2Si2 (u0O 1s core­level spectra in the magnied scale. The denitionof u is also shown in the upper inset.

Fig. 2 The satellite structures in Yb 3d5/2 core­level spectra for (a)YbS and (b) Yb metal, in comparison with bulk loss func­tion Im (1/e) and surface loss function Im [1/(e{1)],where e is the complex dielectric function obtained from themeasured optical reectivity. The dotted lines indicate main
peak positions in loss functions.

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110  úËõ March 2011 Vol.24 No.2

i½Ë¦ÌWjCyÑr[`bvi³Ír³pjðKØÉzuµÈ¯êÎÈçÈ¢B±Ìæ¤ÈñíÉ·¢Fig. 3(a) Schematic diagram of a diamond­anvil cell (DAC). (b)Photograph of the setup for the sample, gold, and ruby inDAC. (c) Comparison of beam prole in the infrared region(0.1_1 eV) between a synchrotron radiation source (SPring­8) and a conventional thermal source (globar lamp).

úËõj[X ¡ æ15ñú{úËõwï§ãÜóÜ¤ñFig. 4(a) The optical conductivity s(v) of YbS at 0.3_20 GPa,and that obtained with KramersKronig analysis of the reec­
tivity spectrum measured in vacuum. The spectra are osetfor clarity. A logarithmic scale is used below 0.1 eV. (b)Pressure dependence of the gap peak, bare plasma frequency(vp), MIR and NIR peaks. (c) Schematic illustrations forthe pressure variation of electronic structures in YbS.

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