Raman spectroscopy of librons and phonons in crystalline C60

摘要: A new era of carbon research has appeared virtiiaHy oveinight following the t 985 discovery fullerenes and development in 1990 an efficient means for their production. Considerable theoretical experimental activity been focused on C60, most symmetrical readily available member fullerene family, particularly vibrational rotational dynamics its solid state phase. In this thesis, phonon spectrum crystalline C60 is studied using technique Raman spectroscopy. The Raman-active intramolecular phonons zre shown to be richly-structured, revealing crystal field splittings molecular vibrations both above below 260 K order-disorder phase transit~on temperature. Surprisingly, majority fine-structure dependent upon presence merohedral disorder (misoriented molecules) within ordered influence isotopic arising from C ~ Q made naturally abundant revealed a minor one through use isotopically engineered crystals. exception behaviour Ag(2)-derived phonon, which complex interaction between effects seen. first optical detection Iibron modes (orientational excitations crystal) reported. Greater structure seen Ramaa-active lattice mode than would expected group-theoretical analysis additional i proposed stem orientational lowtemperature This thesis also prezens ie new, metastable C60. heralded by pronounced changes intermolecular with application hydrostatic pressure. While stabilized high pressures, it remains respect conventional low-pressure provided kept -90K, glass transition model based pressure-induced reordering molecules