Insights into the molecular structure and infrared spectrum of the prebiotic species aminoacetonitrile
Abstract
Aminoacetonitrile is an interstellar molecule with a prominent prebiotic role, already detected in the
chemically-rich molecular cloud Sagittarius B2(N) and postulated to be present in the atmosphere of the
largest Saturn’s moon, Titan. To further support its observation in such remote environments and
laboratory experiments aimed at improving our understanding of interstellar chemistry, we report a
thorough spectroscopic and structural characterization of aminoacetonitrile. Equilibrium geometry,
fundamental bands as well as spectroscopic and molecular parameters have been accurately computed
by exploiting a composite scheme rooted in the coupled-cluster theory that accounts for the
extrapolation to the complete basis set limit and core-correlation effects. In addition, a semiexperimental approach that combines ground-state rotational constants for different isotopic species
and calculated vibrational corrections has been employed for the structure determination. From the
experimental side, we report the analysis of the three strongest fundamental bands of aminoacetonitrile
observed between 500 and 1000 cm1 in high-resolution infrared spectra. More generally, all computed
band positions are in excellent agreement with the present and previous experiments. The only
exception is the ν15 band, for which we provide a revision of the experimental assignment, now in good
agreement with theory
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