J. Phys. IV France
Volume 125, June 2005
Page(s) 19 - 21

J. Phys. IV France 125 (2005) 19-21

DOI: 10.1051/jp4:2005125005

Influence of halogen substitution on optical property of mixed-valence gold halide investigated by photoacoustic spectroscopy

X.J. Liu, D.L. Niu and S.Y. Zhang

State Key Lab of Modern Acoustics, Nanjing University, Nanjing 210093, China

Influence of halogen substitution on the absorption spectra in the mixed-valence gold halide Cs2Au2X6 (X = Cl, Br, and I) has been investigated by means of photoacoustic (PA) spectroscopy in the energy range of 1.0~3.5 eV at 300 K. The optical gap ( $E_{\rm gap}$), which is assigned to the charge transfer from Au+5dx2-y2 to Au3+5dx2-y2 levels, shows a red shift from 1.61 eV for X = Cl to 1.18 eV for X = I. We have ascribed the reduced $E_{\rm gap}$-value to the suppression of the structural distortion of AuX4-.

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