Low-energy electron scattering by tetrahydrofuran

Cross sections for elastic scattering of low-energy electrons by tetrahydrofuran, a prototype for the furanose ring found in the backbone of DNA, have been measured and calculated over a wide energy range, with an emphasis on energies below 6 eV, where previous data are scarce. The measurements employ a thin-aperture version of the relative-flow method, while the calculations employ the Schwinger multichannel method with an extensive treatment of polarization effects. Comparisons with earlier results, both experimental and theoretical, are presented and discussed. A proper accounting for the strong permanent electric dipole of tetrahydrofuran is found to be essential to obtaining reliable cross sections, especially at energies below 5 eV.

Figure 1

Differential cross sections for elastic electron scattering by tetrahydrofuran. The red circles are the present measured values. The solid green and dashed blue lines show the results of the present calculations with and without the Born-dipole correction. The short-dashed magenta line at 2 eV shows the measurements of Allan; see Ref. [15].

Figure 2

As in Fig. 1, at higher energies. Additional measured results shown are those of Colyer et al. [16] (violet squares) and Dampc et al. [17] (cyan diamonds); the calculated results of Trevisan et al. [26] are shown by the orange chained lines.

Figure 3

Differential cross sections for elastic electron scattering by tetrahydrofuran at fixed angles as a function of the collision energy. The present measurements are shown by the red solid line, the present calculated values (without Born-dipole correction) are shown by the blue long-dashed line, and the measurements of Ref. [15] (at 45${}^{\circ }$ in the top panel, and at 135${}^{\circ }$ in the bottom panel) are shown by the magenta short-dashed line.

Figure 4

Symmetry components of the calculated integral cross section for elastic electron scattering by tetrahydrofuran, corresponding to the two irreducible representations of the $C_2$ point group. The Born-dipole correction for near-forward scattering is omitted from these results.

Figure 5

Integral cross sections for elastic electron scattering by tetrahydrofuran. Red circles are present measurements, and the solid green line is the present calculation, both with Born-dipole correction (see text for discussion); the dashed blue line is the uncorrected calculation. Previous measurements of Ref. [16] are shown by violet squares, and the previous calculation of Ref. [25] is shown by the chained magenta line. The total scattering cross-section measurements of Ref. [12] are also included for comparison (black open triangles).

Figure 6

Momentum-transfer cross sections for elastic electron scattering by tetrahydrofuran. Red circles are present measurements, and the solid green is the line present calculation; violet squares are the previous measurements of Ref. [16] and the orange chained line is the previous calculation of Ref. [26].