The rate of water vapor evaporation from ice substrates in the presence of HCl and HBr: implications for the lifetime of atmospheric ice particles

Using a multidiagnostic approach the rate Rev [molec cm−3 s−1] or flux Jev [molec cm−2 s−1] of evaporation of H2O and its corresponding rate constant for condensation, kcond [s−1], on a 1μm thick ice film have been studied in the temperature range 190 to 240 K as well as in the presence of small amounts of HCl and HBr that left the vapor pressure of H2O on ice unchanged. The resulting Arrhenius expressions for pure ice are Jev = 1.6 · 1028±1 · exp ( −10.3±1.2 RT ) [molec cm−2 s−1], kcond = 1.7 · 10−2±1 · exp ( +1.6±1.5 RT ) [s−1], in the presence of a HCl mole fraction in the range 3.2 · 10−5 − 6.4 · 10−3: Jev = 6.4 · 1026±1 · exp ( −9.7±1.2 RT ) [molec cm−2 s−1], kcond = 2.8 · 10−3±1 · exp ( +1.5±1.6 RT ) [s−1], and a HBr mole fraction smaller than 6.4 · 10−3: Jev = 7.4 · 1025±1 ·