Title High - pressure infrared absorption in Cs 2 TCNQ 3 crystals grown under magnetic field

Pressure dependence of infrared absorption has been measured in Cs2TCNQ3 single crystals grown under magnetic field of 5 T (5 T crystals). The behavior of the C-CN as well as C-H stretching modes suggest that there occurs a phase transition which resembles to the one related to the insulator to metal transition in the crystals grown without magnetic field (0 T crystals). This transition, however, takes place at 4.1 GPa, slightly higher than the case of 0 T crystals. The charge transfer degree of the neutral and radical molecules are found to be ρ = 0.30-0.37 and 0.81-0.85, respectively, which are significantly different from that of 0 T crystals. These differences are suggested to arise from the changes in the relative positions of the TCNQ molecules, as indicated from the behavior of the EMV mode. Corresponding author: Dr. Hasanudin Department of Mechanical Engineering and Materials Science, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami Kumamoto 860-8555 Phone: 096-344-2111 ext. 3704 Facsimile: 096-342-3710 e-mail: [email protected]