Pressure dependence of the conduction-band energy of nonpolar liquids

The energy ${\mathit{V}}_0$ of the conduction state of the quasifree electron is reported as a function of pressure up to 2.5 kbar for n-pentane, 2,2-dimethylbutane, 2,2,4-trimethylpentane, 2,2,4,4-tetramethylpentane, and tetramethylsilane (TMS). For each liquid, ${\mathit{V}}_0$ increases with increasing pressure. The largest change with pressure is observed for n-pentane, the smallest change for TMS. The results are used together with a density-fluctuation theory to calculate the effect of pressure on the mobility of quasifree electrons. The theory predicts the direction of change in mobility with pressure found experimentally (decreasing with pressure for TMS and increasing with pressure for branched hydrocarbons) as well as the relative magnitude of the changes.