Speaker
Description
The formation of methanol (CH3OH) on icy grains in cold interstellar clouds is generally related to hydrogenation reactions during the catastrophic CO freeze–out stage. This explains why CO and CH3OH are mixed in interstellar ices. Yet there are reasons to believe that CH3OH can also form at an earlier period of interstellar ice evolution in CO–poor and H2O–rich ices. Here we present a systematic laboratory study to investigate whether CH3OH can be formed in a H2O–rich interstellar ice environment through the solid–state reaction of CH4 and OH, recently investigated theoretically (Lamberts et al. 2017). Using RAIRS and TPD as diagnostic tools, we show that CH3OH formation at 10–20 K can also take place through the sequential chain, CH4 + OH → CH3 + H2O and CH3 + OH → CH3OH. The CH3OH formation efficiency for both schemes is compared, and the astronomical relevance of the formation channel investigated here is discussed.
