Elastic scattering of electrons by polyatomic molecules in the energy range 300-1300 eV: CO, , , H and

Abstract

Differential cross sections (DCS) for the elastic scattering of electrons have been measured by the crossed-beam technique for CO, CO 2 , CH 4 , C 2 H 4 and C 2 H 6 in the angular range 30 • -120 • and at impact energies of 300, 500, 700, 900, 1100 and 1300 eV. The measurements were made with a view to test the validity of the independent atom model (IAM) for polyatomic molecules in this energy region. A comparison of experimental results with the IAM calculations indicates that the model is adequate for the linear molecules CO and CO 2 in the energy region 900-1300 eV. The Born approximation for the evaluation of the atomic scattering amplitudes was found to be valid only at 1300 eV for all the molecules except for C 2 H 6 . A survey of the previous experimental and theoretical data based on different models shows that proper molecular wavefunctions have to be used for the evaluation of short-range potentials and that valence-bond distortion, absorption and non-adiabatic effects in the polarization potential have to be considered.

A Theoretical Study of Scattering of Electrons and Positrons by CO2 Molecule

“…For comparison, the experimental data of [47] are normalized with those of [49] in Figure 1 at 90 • . Additionally included are the theoretical results predicted by the Schwinger variational iterative method (SVIM) of Iga et al [45] at 100, 200, 300, and 400 eV and the IAM approach of Maji et al [51] at 500, 700, and 900 eV. We found no experimental or any other theoretical results with which to compare our calculations for the energy domain of 1500 eV ≤ E i ≤ 10,000 eV.…”

“…The IAMS theory, on the other hand, produces only one minimum up to E i = 200 eV, and beyond that, the DCS shows smooth variation with the energy. In Figures 1-4, our DCS results for the electron projectiles are compared with the experimental data from Tanaka et al [46] that are available at E i = 60-100 eV, as well as those of Shyn et al [47] at E i = 40-90 eV, Register et al [48] at 50 eV, Kanik et al [49] at E i = 40-100 eV, Iga et al [45] at 100, 200, 300, and 400 eV, Bromberg [50] at 300, 400, and 500 eV, Maji et al [51] at 500, 700, and 900 eV, and Iga et al [52] at 500, 800, and 1000 eV. For comparison, the experimental data of [47] are normalized with those of [49] in Figure 1 at 90 • .…”

BEAMDB and MOLD—Databases at the Serbian Virtual Observatory for Collisional and Radiative Processes

“…Their electron beam was produced as secondary electrons from the moderator with the energy spread of several electronvolts. Maji et al [61] measured elastic DCSs for a number of carbon-containing molecules at the high-energy region from 300 to 1300 eV by the crossed-beam technique. They wanted to test the validity of the independent atom model for polyatomic molecules.…”

“…The measurements of DCS were carried out with an energy resolution of about 1 eV and by using the relative flow method at 30 • where the overall uncertainty was 15%. Basavaraju et al [62] gave tabulated values for measured DCSs in [61] and obtained a scaled DCSs regarded as a universal function of a scaled momentum transfer for a number molecular targets.…”

Commission 14: Atomic and Molecular Data: (Donnees Atomiques et Moleculaires)

“…Recent work on elastic collisions between electrons and molecules include H 2 and N 2 (Isaacs & Morrison 1996), NO (Da Paixao et al 1996), C 0 2 (Gianturco k Stoecklin 1996), CO , C 0 2 (Takekawa k Itikawa 1996), 0 2 (Green et al 1997), H 2 0 (Gianturco et al 1998a), 0 3 ), C 0 2 (Tanaka et al 1998), CO, N 2 , NO, and 0 2 (Liu k Sun 1996), and CO, C0 2 , CH 4 , C 2 H 4 , and C 2 H 6 (Maji et al 1998). …”