Electron collisions with trifluorides: BF3 and PF3 molecules

Abstract

Absolute total cross sections (TCSs) for electron scattering from boron trifluoride (BF(3)) and phosphorus trifluoride (PF(3)) molecules have been measured using a linear transmission method. The electron energy ranges from 0.6 to 370 eV for BF(3) and from 0.5 to 370 eV for PF(3). The TCS energy dependence for BF(3) exhibits two very pronounced enhancements: resonantlike narrow feature located near 3.6 eV with the maximum value of 19.2 x 10(-20) m(2), and intermediate energy very broad enhancement with two humps, one centered around 21 eV (18.8 x 10(-20) m(2) in the maximum) and the other near 45 eV (19.5 x 10(-20) m(2)). For PF(3) the TCS has quite different low-energy dependence: at 0.5 eV it has a high value of 70 x 10(-20) m(2) and decreases steeply towards higher energies. Beyond the minimum near 5.5 eV, the TCS reveals two distinct humps: the resonant one centered near 11 eV with the peak value of 32.9 x 10(-20) m(2) and the second one much broader around 35 eV (27.9 x 10(-20) m(2)). The present TCSs for trifluorides are compared to each other as well as to previous TCS data for selected perfluorides and to results for their perhydrided counterparts. The differences and similarities in the shape and magnitude of TCSs are pointed out.

Crossed-beam experiment for the scattering of low- and intermediate-energy electrons from BF3: A comparative study with XF3 (X = C, N, and CH) molecules

“…Finally, the total cross sections summed elastic ICS with inelastic ICS were also found to be nicely consistent with the previous results from TCS measurements of Szmytkowski et al 9 …”

“…In Fig. 7(a), in the whole energy range from 1.5 to 200 eV, we find very good agreement between the present TCS, which is the sum of the elastic with the vibrational ICS and the previous TCS measurements of Szmytkowski et al 9 As far as the total inelastic ICS from the IAM-SCAR calculations is concerned, our experimental TCS also agrees very well in the high energy region, i.e., above 20 eV. We observe that the TCS exhibits a structure in the vicinity of the B 2 shape resonance at 3.5-4 eV and decreases for lower impact energies towards the R-T minimum at 0.7 eV.…”

“…Moreover, both elastic and vibrational excitations are normally enhanced around the shape resonance at 3.8 eV. 9 The energy scale was also calibrated by reference to at an incident energy of 1.97 eV. 33 In both setups, the angular scale and their resolution within ±1.5 • were determined from the symmetry in the intensity profile of the He 2 1 P inelastic transition measured by changing the scattering angle of ±θ against the nominal-scattering angle at 0 • .…”

“…ciative electron attachments, [6][7][8] grand total cross section (TCS) measured by Szmytkowski et al, 9 and calculated ionization and TCS with an independent atom model by Vinodkumar et al 10 Angular differential-vibrational excitation of BF 3 for symmetry stretching v 1 and degenerate stretching v 3 modes were reported as a function of the electron energy with a crossed-beam method by Tronc et al 11 As far as elastic differential cross sections (DCSs) and integral cross sections (ICSs) are concerned, we note a few theoretical studies on multi-scattering Xα-calculation of the unoccupied a ′′ 2 , a ′ 1 , and e ′ molecular orbitals of BF 3 and BCl 3 by Tossel et al 12 which are compared with electron transmission spectroscopy (ETS) measurements as well as R-matrix calculations by Radmilović-Radjenović 13 on the elastic scattering and electronic excitation of BF 3 by low energy electrons. More recently, the Schwinger multichannel (SMC) method was employed in the static-exchange (SE) and the static-exchange-polarization (SEP) approximations in the energy range from 0.1 to 10 eV.…”

Absolute cross section measurements for the scattering of low- and intermediate-energy electrons from PF3. II. Inelastic scattering of vibrational and electronic excitations

“…1). As mentioned therein, prior experimental studies were restricted to the formation of positive and negative ions, [2][3][4] total cross section (TCS) measurements, 5 and absolute photoabsorption oscillator strength determinations for valence and inner shells. 6 From the practical point of view, most of the electron-impact excitation cross section data needed for modeling plasma processes are still not available in the literature.…”