Marcin Gronowski

Computational Chemistry

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Posts Tagged ‘vibrational spectroscopy’

Matrix isolation IR spectroscopic and ab initio studies of C3N− and related species

Coupled cluster calculations were carried out for C3N−, CCNC−, C3N, CCNC, C3N+, and C3O. They support the experimental identification of the C3N− ion by means of matrix isolation infrared IR spectroscopy. The anion was generated in electric discharges through the cyanoacetylene isotopomers HC314N, HC315N, and 2HC3N, trapped in cryogenic rare gas matrices Ne, Ar, Kr, anddetected via its two most intense IR absorption bands, assigned to the 1 and 2 stretching vibrations. C3N− appears to be quite a stable anion, with a vertical detachment energy predicted to be as high as 4.42 eV. A large equilibrium electric dipole moment of 3.10 D facilitates the investigation of C3N− by microwave spectroscopy and radio astronomy. Various structural parameters and spectroscopic properties have been calculated for all tetra-atomic species considered.
Full text: J. Chem. Phys 128 (2008) 154305

Spectroscopy of cyanodiacetylene in solid argon and the photochemical generation of isocyanodiacetylene

Following the measurements of UV and mid-IR spectra of cyanodiacetylene, H-CC2-CN, isolated in low temperature Ar matrices, the first photochemical study on this compound and on its 2H isotopomer was carried out with the laser light tuned to 267 nm and with far-UV discharge lamps. Evidence for the formation of isocyanodiacetylene, H-CC2-CN, was found in infrared absorption spectra interpreted with the aid of available theoretical predictions.
Full text: J. Chem. Phys. 126 (2007) 164301

Isomers of cyanodiacetylene: Predictions for the rotational, infrared and Raman spectroscopy

Recent ab initio (coupled-clusters) and density functional theory studies on cyanodiacetylene isomers are extended here to yield the quantities of direct interest to future spectroscopic investigations. A bond lengths scaling procedure was developed to obtain the corrected molecular geometries. These, together with calculated vibration–rotation coupling constants, yielded the ground-level rotational constants for seven most stable isomeric species of the HC5N stoichiometry. Former calculations regarding the vibrational transitions of these molecules are complemented here with predictions on Raman scattering activities, and on isotopic (2H, 15N) effects in IR absorption and Raman spectra.
Full text: J. Mol. Struct. 834-836 (2007) 102