Electron mobility in supercritical propane as a function of density and temperature

The mobility of electrons (μ) in propane was measured as a function of density (N) at several temperatures above the critical temperature. The quantity μN goes through a minimum at a density just below the critical density and the mobility is quite temperature dependent in this region, as was observed for ethane. Also, μN goes through a maximum above the critical density and becomes quite temperature insensitive at higher densities. The mobility minimum matches a minimum in the velocity of sound in propane and the results at intermediate densities can be accounted for by a Cohen–Lekner equation, utilizing the structure factor S(K). Thus scattering is the result of density fluctuations and a momentum transfer cross section σm of 4 Å2 accounts for the results. At higher densities multiple scattering is important.