Even-odd alternation of evaporation rates and vapor pressures of C3-C9 dicarboxylic acid aerosols

Aliphatic straight-chain dicarboxylic acids have been identified as common water-soluble organic components of atmospheric aerosols. To model the partitioning of such compounds between gas and particle phase in the atmosphere, information about their vapor pressures is essential. In this work, vapor pressures of C3-C9 dicarboxylic acids are derived from measured evaporation rates of submicron aerosols over the temperature range of 290314 K using the tandem differential mobility analyzer technique. Vapor pressures obtained from the experimental data were as follows: log(P-malonic(o), Pa)= -4822 K/T + 12.9, log(P-succinic(o), Pa) = -7196.8 K/T + 19.8, P-glutaric(o) (296 K) = 6.7 x 10(-4) Pa, log(P-adipic(o), Pa) = -8065.0 Kg/T + 22.2, log(P-pimelic(o), Pa) = -7692.8 K/T + 21.8, 109(P-suberic(o), Pa) = P -9629.4 K/T + 26.5, and log(P-azelaic(o), Pa) = -7968.7 K/T + 21.7. Vapor pressures of C3-C9 dicarboxylic acids are shown to alternate strongly with the parity of the number of carbon atoms. Higher vapor pressures of the odd acids fit the less stable crystal structure, the propensity of polymorphism in the odd acids, and the evolution of melting temperatures. Results are compared with available literature data.