Study of the Vibrational Spectra and Absorption Cross Sections of 1-Chloro-1-fluoroethene by a Joint Experimental and Ab Initio Approach

Abstract

The gas-phase infrared spectra of 1-chloro-1-fluoroethene (geminal chloro-fluoroethene, ClFC=CH, 1,1-CHClF) were recorded at medium resolution in the range 400 - 6400 cm and the vibrational analysis led to revise the previous assignments for the ν (A'' symmetry), ν (A' symmetry) and ν (A' symmetry) bands. Besides the fundamentals, all the most relevant spectral features were interpreted in terms of overtone and combination bands, thus obtaining an accurate description of the vibrational structure of ClFC=CH2. Accurate measurements of absorption cross section spectra were carried out and integrated band intensity data were determined. High-level ab initio calculations of harmonic and anharmonic force fields thoroughly supported and guided the analysis and the disentangling of the several strongly coupled polyads involving many vibrational levels. Diagonalization of the effective Hamiltonian with the off-diagonal elements involving several Fermi and Darling-Dennison resonance coefficients computed by the theoretical cubic and quartic force constants provided the predicted energy levels in good agreement with the vibrational assignments. The calculated infrared intensities, obtained by taking into account anharmonic corrections, were compared to the accurate experimental absorption cross section data here determined.

Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

“…The SNSD basis set is obtained by adding to 6-31G(d,p) the diffuse functions of the aug-cc-pVDZ basis set and, for non-hydrogen atoms, a very tight s function. It is noteworthy that Cartesian, (e.g., 6d) functions were used in the original implementation and must be retained because, as is well known, this choice effectively increases also the (Isoniemi et al, 1999), formaldehyde (Reisner et al, 1984), thioformaldehyde (Suzuki et al, 2007), ethylene (Nakanaga et al, 1979), 1,1-difluoroethylene (Krasnoshchekov et al, 2013), fluoroethylene (Tasinato et al, 2006), 1-fluoro-1-chloro-ethylene (Pietropolli Charmet et al, 2016).…”

“…The values are indicated on top of the bars. Reference experimental data taken from: water(Tennyson et al, 2001), H 2 S(Isoniemi et al, 1999), formaldehyde(Reisner et al, 1984), thioformaldehyde(Suzuki et al, 2007), ethylene(Nakanaga et al, 1979), 1,1-difluoroethylene(Krasnoshchekov et al, 2013), fluoroethylene(Tasinato et al, 2006), 1-fluoro-1-chloro-ethylene (PietropolliCharmet et al, 2016).…”

Accuracy Meets Interpretability for Computational Spectroscopy by Means of Hybrid and Double-Hybrid Functionals

“…We will consider, in particular, equilibrium geometries, ground state rotational constants and quartic centrifugal distortion constants, harmonic and anharmonic vibrational wavenumbers and IR intensities. The benchmark study is carried out on a set of ten molecules of atmospheric and astrochemical relevance, reported in Figure 1, which includes: difluoromethane (CH 2 F 2 ) (Carlotti et al, 1988;Tasinato et al, 2012b;Piccardo et al, 2015b), chlorofluoromethane (CH 2 ClF) (Blanco et al, 1995;Pietropolli Charmet et al, 2013), cis-1-chloro-2-fluoroethene (cis-ClHC=CHF) (Craig et al, 1970;Alonso et al, 1993;Gambi et al, 2002;Piccardo et al, 2015b), 1-chloro-1-fluoroethene (ClFC=CH 2 ) (Leung et al, 2009;Pietropolli Charmet et al, 2016;Gambi et al, 2019), chlorotrifluoroethene (F 2 C=CFCl) (Hillig et al, 1988;Tasinato et al, 2012a), oxirane (cyc-C 2 H 4 O) (Russell and Wesendrup, 2003;Flaud et al, 2012;Medcraft et al, 2012;Lafferty et al, 2013;Puzzarini et al, 2014a;Piccardo et al, 2015b), glycolaldehyde (HOCH 2 CHO) (Carroll et al, 2010;Johnson et al, 2013;Piccardo et al, 2015b;Boussessi et al, 2020a), E-ethanimine (CH 3 CHNH) (Melli et al, 2018), sulfur dioxide (SO 2 ) (Flaud et al, 1993;Mller and Brnken, 2005;Tasinato et al, 2010;Boussessi et al, 2020a), and the gauche conformer of ethyl mercaptan (CH 3 CH 2 SH) (Smith et al, 1968;Wolff and Szydlowski, 1985;Miller et al, 2009;…”

The Spectroscopic Characterization of Halogenated Pollutants through the Interplay between Theory and Experiment: Application to R1122

“…Their individual integrated intensities range from 1.8 to 2.7 × 10 cm molecule , and their overall sum is equal to 8.50 × 10 cm molecule . At this point, it is worthwhile to note that the overall cross section of R1122 in the atmospheric window (900–1400 cm ) can be considered as rather large (around 5.9 × 10 cm molecule ), in line with that of other similar halogenated ethenes (for comparison, ClFC=CH has an integrated value of almost 4.5 × 10 cm molecule ; see [ 23 ], whereas that of ClFC=CF is around 9.3 × 10 cm molecule , see [ 25 ]).…”

“…Within this framework, several investigations (see, for example, refs. [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ] and references therein) have been carried out to disentagle the anharmonic interactions in their vibrational spectra and to assess the quality of the predicted dipole moment surfaces against the spectroscopic experimental data.…”