Collisions of low-energy electrons with isopropanol

We report measured and calculated cross sections for elastic scattering of low-energy electrons by isopropanol (propan-2-ol). The experimental data were obtained using the relative flow technique with helium as the standard gas and a thin aperture as the collimating target gas source, which permits use of this method without the restrictions imposed by the relative flow pressure conditions on helium and the unknown gas. The differential cross sections were measured at energies of 1.5, 2, 3, 5, 6, 8, 10, 15, 20, and 30 eV and for scattering angles from 10${}^{\circ }$ to 130${}^{\circ }$. The cross sections were computed over the same energy range employing the Schwinger multichannel method in the static-exchange plus polarization approximation. Agreement between theory and experiment is very good. The present data are compared with previously calculated and measured results for $n$-propanol, the other isomer of C${}_3$H${}_7$OH. Although the integral and momentum transfer cross sections for the isomers are very similar, the differential cross sections show a strong isomeric effect: In contrast to the $f$-wave behavior seen in scattering by $n$-propanol, $d$-wave behavior is observed in the cross sections of isopropanol. These results corroborate our previous observations in electron collisions with isomers of C${}_4$H${}_9$OH.

Figure 1

Geometrical structure of C${}_3$H${}_7$OH isomers. Left, isopropanol; right, $n$-propanol.

Figure 2

Differential cross sections for isopropanol. Solid (green) line, present computed results; squares (magenta), present experimental data.

Figure 3

Differential cross sections for the C${}_3$H${}_7$OH isomers at selected energies. Solid (green) line, present computed results for isopropanol; dashed (blue) line, $n$-propanol; squares (magenta), present experimental data for isopropanol; open circles (red), experimental data for $n$-propanol. The results for $n$-propanol were taken from Ref. [2].

Figure 4

Calculated differential cross sections for (a) isopropanol, (b) isobutane, (c) isobutanol, (d) $n$-propanol, (e) $n$-butane, and (f) $n$-butanol at 6, 7, 8, 9, and 10 eV. The results for isobutane and $n$-butane are from Ref. [12], those for isobutanol, from Ref. [3], and those for $n$-propanol and $n$-butanol from Ref. [2]. See text for discussion.

Figure 5

Integral cross sections for the C${}_3$H${}_7$OH isomers. Solid (green) line, present computed results for isopropanol; dashed (blue) line, $n$-propanol; squares (magenta), present experimental data for isopropanol; open circles (red), experimental data for $n$-propanol. The results for $n$-propanol were taken from Ref. [2].

Figure 6

Momentum transfer cross sections for the C${}_3$H${}_7$OH isomers. Solid (green) line, present computed results for isopropanol; dashed (blue) line, $n$-propanol; squares (magenta), present experimental data for isopropanol; open circles (red), experimental data for $n$-propanol. The results for $n$-propanol were taken from Ref. [2].