Experimental vapour pressures of eight n-alkanes (C_(17), C_(18), C_(20), C_(22), C_(24), C_(26), C_(28) and C_(31)) measured at ambient temperatures

摘要

We present direct room-temperature vapour pressure measurements for eight semi-volatile n-alkanes of atmospheric importance. Measured vapour pressures range from 8.4 +/- 1.6 x 10(-3) Pa for C-17, to 1.7 +/- 0.6 x 10(-8) Pa for C-31. The new measurements for C-17-C-18 are in reasonable agreement but at the lower end of values in the literature; the new measurements for C-28 and C-31 are one-to-two orders of magnitude higher than most literature values, but six orders of magnitude higher than the lowest values in the literature. Our measurements are suitable for atmospheric aerosol modelling and interpretation of environmental measurements, interpolated in carbon number where necessary, and extrapolated over temperatures relevant to the atmospheric boundary layer using the Clausius-Clapeyron equation with literature values of the enthalpy of vaporisation.