Electronic properties and primary dissociation channels of fluoromethane compounds

Abstract

We investigated fluoromethane compounds (CF4, CF3, CHF3, CH2F2, and CH3F) to examine their electronic properties and primary dissociation channels by using computational chemistry. For the electron attachment process, it was very important to represent the observed negative mass spectrum as a function of electron energy that calculation by the MP2 method for the negative ion and subsequent calculation by the EOMCCSD method were used to more accurately estimate the ground and the first excited states of the negative ion. In the evaluation of dissociation channels through the excitation process, the structure change of the excited fragment (from pyramidal to planar) was taken into account. Evaluation of Jahn–Teller distortion for the highly symmetrical CHF3 and CH3F was also very important to estimate the fragmentation process through the excitation. The calculated results after these treatments gave satisfactory representation of the experimental values. Moreover some predictions of experimentally unknown values are proposed.

Plasma-relevant fast electron impact study of trifluoromethane

“…In order to compare the present experimental results with the available data, the photoabsorption spectra was simulated from the extrapolated OOS data and the fitted natural linewidths. The comparison was made in figure 6 also with the recent quantum chemistry calculation [18]. The reproduced spectrum generally agrees well with the photoabsorption measurement.…”

“…The electron swarm method has also contributed to an estimation of electron collision cross sections for CHF 3 [17]. More recently, the electronic properties and dissociation channels were investigated by Hayashi et al [18] by using the computational chemistry. However, most of the experimental data were measured decades ago.…”

Dissociation channels of c-C4F8 to C2F4 in reactive plasma

“…The negatively ionized states and their energies were estimated using B3LYP/6-311 G+(d) and MP2/cc-pVTZ without diffuse function, which give very accurate electron attachment energies for perfluorocarbon molecules. 26) And the excited states of the negative ion were obtained by a subsequent calculation using EOMCCSD/aug-cc-pVDZ and TD-SCF CAM-B3LYP/aug-cc-pVDZ. These calculations were carried out using the Gaussian 09 program.…”

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

“…118) The electron impact ionization process of C 3 F 6 O has been reported. 119) The primary dissociation channels of hydrofluoro compounds were predicted through quantum chemical calculations, [120][121][122][123] including fluoromethane compounds (e.g. CF 4 , CF 3 , CHF 3 , CH 2 F 2 , and CH 3 F), 120) fluoroethane compounds, 121) and 1,1,1,2-tetrafluoroethane (HFC-134a).…”

“…119) The primary dissociation channels of hydrofluoro compounds were predicted through quantum chemical calculations, [120][121][122][123] including fluoromethane compounds (e.g. CF 4 , CF 3 , CHF 3 , CH 2 F 2 , and CH 3 F), 120) fluoroethane compounds, 121) and 1,1,1,2-tetrafluoroethane (HFC-134a). 122) Among these, 1,1,2trifluoroethane (CH 2 FCHF 2 ) was examined for the generation of CH 2 F and CHF 2 radicals and ions by quadrupole mass spectrometry.…”