Order-disorder transition in polycrystalline c60 films.
High-resolution Raman spectroscopy of polycrystalline films of C(60) deposited under ultrahigh-vacuum conditions show that the spectrum below 244 +/- 3 kelvin consists of a superposition of two components whose relative contributions are temperature-dependent. The spectrum of the more intense of the two components is similar to that obtained for air- or oxygen-exposed samples of C(60) at room temperature, whereas the spectrum above 244 +/- 3 kelvin corresponds to one previously reported for oxygen-free samples of C(60). The results may indicate an order-disorder phase transition involving the percolation of a cluster of C(60) molecules engaged in coherent Raman scattering.
Akers
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Fu
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Zhang
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Moskovits
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