Molecular complexity in dark clouds – A laboratory approach

Understanding how complex organic molecules (COMs) form and survive in space throughout the process of star and planet formation is a key step to unraveling of the origin of life on the Earth. From dedicated laboratory studies it has become clear that the larger molecules cannot be formed efficiently in the gas phase. Interstellar dust grains represent a valid alternative because they provide surfaces on which gas-phase species can accrete, meet, and react, and to which they can donate excess energy. Therefore, in dense cold clouds, icy dust grains act both as a molecular reservoir and as sites for catalysis. For decades, surface complex molecule formation has been thought to be triggered largely by energetic processing. However, the recent detection of COMs in dark cold molecular clouds motivated astrochemists to look for other possible formation mechanisms. Very recently, my co-workers and I gave the first laboratory evidence that the building blocks of sugars, fats, and proteins can be formed through non-energetic induced surface reactions during the ‘catastrophic’ freeze-out of CO in dark molecular clouds (Fedoseev et al. 2015). Moreover, novel combined laboratory THz techniques (i.e., time-domain, radiometry and free electron laser) have the potential to allow the future detection of solid COMs in the interstellar medium and at the same time understand molecular dynamics and desorption mechanisms of complex species by exploring interlayer vibrational and single molecule torsional modes of ices, phonon modes in solids, and the rovibrational transitions of larger gas-phase species at the gas-solid interface. This talk will review my most recent laboratory work performed in collaboration with the Sackler Laboratory for Astrophysics (Leiden University, NL), the Blake Research Group (Caltech, US), the FELIX facility (Radboud University Nijmegen, NL) and RAL Space (Oxford, UK).