Gas phase spectroscopic recognition of complex organic molecules in space

It is commonly believed that accumulation of organic molecules of increasing complexity is an important step in the series of events that led from elementary particles to the emergence of life. For this reason a lot of resources have been and are currently devoted to the discovery and quantification of molecular species in extra-terrestrial environments. Through the recognition of the rotational spectral lines, radioastronomy represents one of the most important techniques for the unequivocal detection of complex organic molecules (COMs) in circumstellar envelopes and interstellar medium (ISM): of the among 130 compounds that have been detected about 90 species are neutral molecules, that typically are characterized by functional groups common in organic chemistry, such as amines, alcohols, aldehydes, ketones, etc. COMs of greater size are expected to be detected exploiting the increasing sensitivity and resolution of new radiotelescopes, therefore the challenge is nowadays twice: (i) on the one hand the spectral analysis of the huge amount of data contained in the ongoing astronomical observations, (ii) on the other hand the laboratory observation and assignment of the rotational spectra of COMs, which are often complicated due to flexibility typical of these molecules. Considering these tasks, we will here present first the rotational spectra of some COMs recorded in laboratory, highlighting the relationships between the spectral features and the conformational landscapes, then an example of spectral survey achieved by data reduction of the freely available Atacama Large Millimeter/submillimeter interferometer Array (ALMA) data on Class 0 protostellar binary IRAS 16293-2422, evidencing the issues related to the molecular recognition in dense spectra.