CO2 depth profiles in cometary model substances of KOSI

The CO2 content of cometary analogs used in comet simulation experiments (KOSI-3) and -4) was measured by gaschromatography. CO2 depth profiles were determined after insolation in cm layers taken from the samples which orginally contained 14-15% frozen CO2. These profiles show an upper layer completely depleted of the volatile component, while the deeper layers are not affected. Of special interest is a transition layer where the CO2 content ranges from 0% to a value which is higher than that of the starting material (> 20%). This is interpreted as inward diffusion of CO2 which can recondense in colder zones. In addition a correlation with the temperature profiles has been observed. The upper and lower layers show a rather constant but different temperature, while a very steep temperature gradient is found in the transition layer. The water-ice profile did not show any significant change with respect to the starting material