Observation of crossover from ballistic to diffusion regime for excimer molecules in superfluid 4He

Zmeev, Dmitriy and Papkour, F. and Walmsley, P. M. and Golov, A. and McClintock, Peter V. E. and Fisher, Shaun N. and Guo, Wei and McKinsey, D. N. and Ihas, Gary G. and Vinen, W. F. (2013) Observation of crossover from ballistic to diffusion regime for excimer molecules in superfluid 4He. Journal of Low Temperature Physics, 171 (3-4). pp. 207-213. ISSN 0022-2291

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Abstract

We have measured the temperature dependence of the time of flight of helium excimer molecules He2 (a3 Σ + u ) in superfluid 4He and find that the molecules behave ballistically below ∼100 mK and exhibit Brownian motion above ∼200 mK. In the intermediate temperature range the transport cannot be described by either of the models.