HR: 1340h
AN: A53A-0166    [Abstracts]
TI: Isotope Fractionation During Evaporation of Water Without Condensation
AU: * Cappa, C D
EM: cappa@berkeley.edu
AF: University of California, Berkeley, UC Berkeley Dept. of Chemistry, Berkeley, CA 94720-1460
AU: Drisdell, W
A53A-0166 AF: University of California, Berkeley, UC Berkeley Dept. of Chemistry, Berkeley, CA 94720-1460
AU: Smith, J D
A53A-0166 AF: University of California, Berkeley, UC Berkeley Dept. of Chemistry, Berkeley, CA 94720-1460
AU: Saykally, R J
A53A-0166 AF: University of California, Berkeley, UC Berkeley Dept. of Chemistry, Berkeley, CA 94720-1460
AU: Cohen, R C
A53A-0166 AF: University of California, Berkeley, UC Berkeley Dept. of Chemistry, Berkeley, CA 94720-1460
AB: The microscopic events engendering liquid water evaporation have received much attention over the last century, but remain incompletely understood. We present measurements of isotope fractionation occurring during free molecular evaporation from liquid microjets and show that the isotope ratios of evaporating molecules exhibit dramatic differences from equilibrium vapor values, strong variations with the solution deuterium mole fraction, and a clear temperature dependence. These results indicate the existence of an energetic barrier to evaporation and that the evaporation coefficient of water is less than unity, i.e. water does not evaporate at the Hertz-Knudsen rate. These new insights into water evaporation promise to advance our understanding of the processes that control the formation and lifetime of clouds in the atmosphere.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005