Abstract book - Prof. Per Jensen, Ph.D. - Bergische Universität ...

Poster session, D6 53A joint experimental and computational study on the vibrational andro-vibrational spectroscopy of HFC-32Nicola Tasinato 1 , Giorgia Regini 1,2 , Paolo Stoppa 1 , Andrea Pietropolli Charmet 1 ,Alberto Gambi 3Tasinato N.Regini G.Stoppa P.Pietropolli CharmetGambi A.1 Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia,Calle Larga S. Marta 2137, I–30123 Venezia, Italy, tasinato@unive.it; 2 Presentaddress: Università degli Studi di Trieste, Piazzale Europa 1, I-34127 Trieste, Italy;3 Dipartimento di Chimica, Fisica e Ambiente, Università degli Studi di Udine, ViaCotonificio 108, I–33100 Udine, ItalyDifluoromethane (CH 2 F 2 , HFC-32) is a hydro-fluorocarbon which has been proposed asa valid replacement for the more environmentally hazardous CFCs and HCFCs. Inparticular, its mixture with CF 3 CH 3 , CF 3 CH 2 F and CF 3 CHF 2 is widely used asrefrigerant. Because of the commercial applications, the atmospheric concentration ofCH 2 F 2 has increased rapidly since 1990s and its abundance was 3 pptv in 2005. Further,owing to the high dipole moment of 1.9785 D, CH 2 F 2 has attracted attention as anefficient laser medium for the generation of strong far infrared laser lines when opticallypumped by CO 2 lasers. Therefore, over the years this molecule has been the subject ofseveral experimental and theoretical investigations.In this contribution we present the results of an integrated experimental and theoreticalstudy about the vibrational and ro-vibrational properties of CH 2 F 2 . The gas-phasespectra have been investigated at medium resolution (0.2 - 1 cm -1 ) in the range 400 -7000 cm -1 and integrated absorption cross sections have been determined over the 400 -5000 cm -1 region. Ab initio calculations, carried out at the CCSD(T) level in conjunctionwith large basis sets of either the correlation-consistent or the atomic natural orbitalhierarchies, have been performed to generate both the potential energy- and dipolemoment-surfaces. Vibrational as well as ro-vibrational parameters have beendetermined from the VPT2 treatment of the quartic-semidiagonal PES, and theanharmonic couplings within the ν1, 2ν2, 2ν8three level system have beenmodelled. Spectral simulations, which reproduce the partially resolved rotationalstructure of the observed spectra, have been performed by using the ro-vibrationalHamiltonian constants and the relevant coupling terms computed ab initio. Work is inprogress for extending the vibrational quantum assignment in the NIR region up to12000 cm -1 as well as for the computation of a full quartic force field.