Intrinsic localized vibrational modes in a halogen-bridged Pt complex were studied by Raman spectroscopy. We compared the peak frequency of the overtone of Pt-Cl stretch vibration between that excited by an Ar+ and that by a near infrared (NIR) lasers. The decrease in the overtone peak frequency of the NIR excitation were larger than that of the visible excitation. We interpreted that the charge transfer led to weaken the bond strength and that the anharmonicity of the system became weak. (C) 2001 Elsevier Science B.V. All rights reserved.