Interstellar ice surface site modification induced by dicyanoacetylene adsorption.

Dicyanoacetylene adsorbed on amorphous ice water at 10 K presents an interaction with the dangling H site and induces a s(4) adsorption site formation due to the restructuring of the ice bulk. Warming up the sample provokes the dicyanoacetylene desorption from the H(2)O ice film, which could be due to the beginning of the ice crystallization process. The desorption activation energy measured by temperature-programmed desorption (E(d) = 42 +/- 5 kJ x mol(-1)) is in good agreement with that calculated (E(d) = 46 kJ x mol(-1)) and gives evidence of a hydrogen-bonded adsorbed state on amorphous ice films.