Low temperature phase transition in n-pentane C 60 clathrate: a Raman scattering study

Abstract

We present results on Raman scattering from a C 60.n-pentane (C 60.(n- C 5 H 12) 0.88( C 7 H 8) 0.05) clathrate crystal in the range 20–300 K. The Raman intensity, in particular of the H g modes, increases several times with lowering temperature below 160–200 K accompanied by significant reduction of the linewidths. The onset of this peculiar temperature behavior correlates with the reported phase transition in n-pentane clathrate. We argue that these findings give a Raman scattering signature for a low-temperature orientational phase transition in C 60.n-pentane similar to that observed for solid C 60.