From the laboratory to the interstellar medium: a strategy to search for exotic molecules in space

Abstract

The chemistry of the interstellar medium occurs under extreme conditions and can lead to the formation of exotic molecules. These are species that on Earth are unstable and/or highly reactive. Their discovery in space is usually based on the astronomical observation of their rotational fingerprints, which requires an accurate laboratory investigation. This is based on a strategy that starts from the interplay of experiment and theory. State-of-the-art quantum-chemical calculations are used to predict the relevant spectroscopic information required to guide the spectral recording, analysis and assignment. Rotational spectra measurements are then performed in the centimeter-/millimeter-/submillimeter-wave region, thereby exploiting efficient on-the-fly production protocols for exotic molecules. Subsequently, the spectral analysis leads to accurate spectroscopic parameters, which are then used for setting up accurate line catalogs for astronomical searches and detections. This review is based on the strategy developed and the results obtained at the ROT&Comp Lab of the University of Bologna.

Tracing Prebiotic Molecules: Rotational Spectroscopy of Deuterated Glycolaldehyde and (Z)-1,2-Ethenediol

“…To exploit FVP at its best, the solid precursor was heated using a heating tape at temperatures around 50 °C in order to make its vapors flow inside a 30 cm long quartz tube surrounded by a tubular oven set at 750 °C. The same setup was already employed to produce other unstable species of astrochemical interest. − As in previous experiments, the quartz tube was connected to the millimeter/submillimeter-wave frequency-modulation spectrometer (see next section) so that the vapors of the pyrolysis products could flow directly through the absorption cell. The optimal working pressure inside the cell was found to be in the 10–20 μbar range.…”

Interstellar Ices: A Factory of the Origin-of-Life Molecules

“…The outcomes are the so-called radioastronomical spectra, which are usually extremely complex because of overlapping features due to tens (or even hundreds) of molecules. Consequently, the identification of 1 in the ISM requires its accurate spectroscopic characterization in the laboratory in order to search for its fingerprints in the "radioastronomical-spectra forest" 9,10. More generally, what is the guidance toward new discoveries?…”

“…The outcomes are the so-called radioastronomical spectra, which are usually extremely complex because of overlapping features due to tens (or even hundreds) of molecules. Consequently, the identification of 1 in the ISM requires its accurate spectroscopic characterization in the laboratory in order to search for its fingerprints in the “radioastronomical-spectra forest”. , More generally, what is the guidance toward new discoveries? Laboratory studies, such as the one presented by Kaiser, Chang, and co-workers, able to reproduce the interstellar conditions and couple the gas- and condensed-phase compositions, pave the way for understanding the chemical complexity in space.…”