The interaction of HCl with water-ice at tropospheric temperatures

The uptake of HCl on frozen film ice surfaces was studied as a function of temperature and HCl partial pressure (P-HCl) in a flow reactor. The tempera tures ranged from 205 to 230 K, and P-HCl was (0.4-2.0)x 10(-6) Torr. The i nitial uptake coefficients, gamma, and the HCl surface coverage are reporte d. It was observed that the coverage varied from 3.0x10(14) molecules/cm(2) at 205 K to 1.0x10(14) molecules/cm2 at 230 K. At 205 K the coverage showe d no dependence on P-HCl; the average surface coverage was similar to (2.0 +/-0.7)x 10(14) molecules/cm(2) at saturation. This value is consistent wit h other studies on similarly prepared ice films. It was found that gamma si milar to0.1 at 205 K, but decreased substantially when the temperature incr eased; however, gamma was insensitive to P-HCl.