Elastic scattering of low-energy electrons by NF₃

Abstract

We present results of e--NF3 collision calculations for energies up to 60 eV. To compute the elastic integral, differential, and momentum-transfer cross sections we have employed the Schwinger multichannel method implemented with norm-conserving pseudopotentials (Bettega M H F, Ferreira L G and Lima M A 1993 Phys. Rev. A 47 1111) within the fixed-nuclei static-exchange approximation. We have compared our results with the complex Kohn results of Rescigno and with the experimental data of Boesten et al, and found them in general good agreement. We have found two independent shape resonances in the NF3 elastic integral cross section, and through its symmetry decomposition we assigned them to the A1 and E representations of the C3v group. The existence of a shape resonance has also been reported by Rescigno and also by Boesten et al, who assigned it to the E representation of the C3v group. We have also discussed the possible role of these shape resonances in the dissociative attachment of NF3 by electron impact.

Cross Sections for Electron Collisions with NF3

“…The experimental data by Boesten et al 15 is not complete, especially, at energies below 1 eV. Out of the three theoretical studies 22,23,25 , the most recent one by Hamilton et al 25 appears to be the most accurate one due to a more accurate method (complete active space-configuration interaction) and a larger basis set employed. However, the position of the resonance near 1 eV in this study is shifted towards lower energies compared to the experimental data.…”

“…• , was published by Boesten et al 15 Subsequently, a Schwinger multichannel theoretical approach 23 reported corresponding cross sections for 14 . Values at 100-500 eV are obtained from parameters of the BetheBorn plot, Fig.…”

“…The momentum-transfer cross section for electron-NF 3 collisions was determined in the same studies, mentioned above 15,22,23,25 , where the elastic cross sections were measured or computed. The experimental data by Boesten et al 15 is not complete, especially, at energies below 1 eV.…”

“…The values of the recommended data given in Table IV. Lisovskiy et al 26 measured the drift velocity of electrons in NF 3 in a limited range of high reduced electric field E/p and compared their measurements with the results of the BOLSIG+ calculations using the momentum transfer cross sections of Boesten et al 15 , and Joucoski and Bettega 23 . Agreement was satisfactorily, especially with calculation using the latter momentum transfer cross section.…”

“…In spite of its importance, experimental studies of electron scattering on NF 3 are rather sparse: for total 14 and elastic 15 cross section measurements come from single laboratories, more measurements exist for ionization [16][17][18] and dissociative electron attachment [19][20][21] . In absence of experiments, several calculations [22][23][24][25] have been performed. Some reference cross sections based both on experiments a) Electronic mail: corresponding author at mysong@nfri.re.kr and calculations were reported by Lisovskiy et al 26 in modeling electron transport coefficients and by Huang et al 1 for modeling remote plasma sources in NF 3 mixtures.…”