SOLEIL and ALMA views on prototypical organic nitriles: C2H5CN

Abstract

The high resolution vibrational spectrum of ethyl cyanide (C 2 H 5 CN) has been investigated in the far-IR using synchrotron-based Fourier transform spectroscopy. The assignment was performed using the Automated Spectral Assignment Procedure (ASAP) allowing accurate rotational energy levels of the four lowest fundamental vibrations of the species, namely the v 13 = 1 @ 205.934099(8) cm −1 , and v 21 = 1 @ 212.141101(8) cm −1 , v 20 = 1 @ 372.635293(15) cm −1 , v 12 = 1 @ 532.699617(16) cm −1 states, to be determined. The analysis not only confirms the applicability of the ASAP in the treatment of (dense) highresolution infrared spectra but also reveals some of its limitations. Complementary to the infrared study, the pure rotational spectrum of C 2 H 5 CN was also studied in selected frequency ranges from 75 to 255 GHz. New observations of a prototypical high-mass star-forming region, G327.3−0.6, performed with the Atacama Large Millimeter Array show that vibrational satellites of C 2 H 5 CN can be very intense, of order several tens of Kelvin in units of brightness temperature.

A Q-band Line Survey toward Orion KL Using the Tianma Radio Telescope

“…To identify the emission of molecular lines, we consulted the frequencies of molecular transitions from the databases at the CDMS 13 (Müller et al 2001), the JPL 14 (Pickett et al 1998), and the Splatalogue. 15 The transition parameters of C 2 H 5 CN υ13/υ21 are adopted from Endres et al (2021).…”

The eight lowest-energy vibrational states of benzonitrile: analysis of Coriolis and Darling-Dennison couplings by millimeter-wave and far-infrared spectroscopy

“…In turn, such detections can help to provide additional confirmation of the presence of the molecule, eliminate "unknown" or unassigned transitions in an observed survey spectrum [42], and offer insight into the environment where the molecule is detected (or not detected). Since transition intensities are linked to abundance, vibrational energies, and temperature, they may provide additional means to estimate properties such as temperatures or molecular abundance in distant regions [31,[43][44][45].…”

Characterization of the Coriolis Coupled Far-Infrared Bands of syn-Vinyl Alcohol

“…Low frequency vibrational bands, like the ν 15 (OH torsion) fundamental of syn -VA investigated here, fall in the far-IR, where the advantage of using synchrotron generated radiation is most pronounced . As such, a rapidly growing number of “complex” molecules (with low frequency torsional bands) have been investigated by far-IR synchrotron spectroscopy, including the OH containing chromophores, perchloric acid, phenol, formic acid, acetone, methanol, glycolaldehyde, and catechol, and the CN containing chromophores, vinyl acetylene, cyanoadamantane, phenylpropiolonitrile, ethyl cyanide, aminoacetonitrile, and benzonitrile, the latter of which are particularly well suited for radioastronomy (on account of their very large dipole moments).…”