Cationic and anionic states of CF, CCl, SiF and SiCl. Some new information derived using translational energy spectroscopy

Extensive theoretical study on the low‐lying electronic states of silicon monofluoride cation including spin‐orbit coupling

“…Additionally, the dissociation energy (D e ) value of 7.00 eV is very close to the experimental value of 6.97 6 0.06 eV, 15 and this agreement could be further modified after the SO coupling effects are taken into account (see Potential Energy Curves and Spectroscopic Constants of the X States section). The cal-culated value of T e (38,581 cm 21 ) for the a 3 P state with the active space of (8,8) is also in good agreement with the experimental value, 16 37,908 6 1613 cm 21 . Table 1 also shows us that our calculational spectroscopic values for X 1 S þ and a 3 P are very close to those computed by Peterson et al, 23 and the small differences may be due to the different choices of active spaces and basis sets, and the fact that our icMRCI þ Q computations used the balanced orbitals from the 18 state-averaged CASSCF calculations.…”

“…Moreover, their equilibrium bond lengths are almost 1 A ˚more than that of the ground state and thus the Franck-Condon factors will be very small and the transitions from the ground state would be hard to be observed in experiment. These are consistent with the experimental measurements of Reid, 16 who found only one peak corresponding to the X 1 S þ ?a 3 P excitation and other excitation peaks were absent in the translational-energy spectra due to the instability. Furthermore, the PECs for the (2) 1 P and (2) 3 P states are repulsive without any type of minimum in the range of R investigated.…”

“…is 12.05 eV, and is in excellent agreement with the value of 12.04 eV suggested by Reid. 16 Our computed vertical IP of X 2 P SiF to A 1 P SiF þ (7r??) is 14.62 eV, and is larger than that obtained by Karna and Grein, 24 but is still lower than the experimental value reported by Bredohl et al 17 This difference may be partially caused by the blue-shift of the absorption peak of A state of SiF þ in Figure 1 of ref.…”

“…Fisher et al 15 obtained 0 K bond dissociation energies of SiF þ 1-4 and adiabatic ionization energies for the SiF 1-4 species using the guided ion beam mass spectrometry. In 1996, Reid 16 obtained the a 3 P cationic state energies and adiabatic electron affinities of SiF by translationalenergy spectroscopy. More recently, Bredohl et al 17 observed three bands with the ionization potentials of 7.31 6 0.02, 15.12 6 0.12, and 17.27 6 0.13 eV, respectively in their study of the vacuum ultraviolet absorption spectra of SiF, which were assigned to three electronic states of SiF þ .…”

The dissociative recombination of fluorocarbon ions: II. CF+

“…In that study, the CF + ions were produced by electron impact on CF 4 while Morris et al used CF 3 Br as the parent gas. Other authors [10][11][12][13][14] have also found the presence of excited CF + states when the ion is produced from a fluorocarbon precursor. Reid [14] was able to quantify the percentage of the a 3 state in a beam of CF + using a measurement of translational energy loss spectroscopy, where he studied the energy loss due to excitation of the CF + ions in the beam by collision with a target gas.…”