Absolute angle-differential elastic cross sections for electron collisions with diacetylene

We report measured and calculated differential elastic cross sections for collisions of low-energy electrons with diacetylene (1,3-butadiyne). A generally satisfactory agreement between theory and experiment has been found. The calculated cross sections provide interesting insight into the underlying resonant structure.

Figure 1

Elastic cross sections at 20${}^{ˆ}$. Solid (red) line, experiment; dashed (blue) line, theory.

Figure 2

Elastic cross sections at 45${}^{ˆ}$.

Figure 3

Elastic cross sections at 90${}^{ˆ}$.

Figure 4

Elastic cross sections at 135${}^{ˆ}$.

Figure 5

Elastic cross sections at 180${}^{ˆ}$.

Figure 6

Contributions of different irreducible representations of the $D_{2h}$ subgroup to the calculated integral elastic cross section. The last two panels on the bottom row contain two curves, which at most energies coincide within the width of the lines.

Figure 7

Angular distributions of the elastic cross sections. Yellow circles indicate individual absolute measurements by the relative flow method, the continuous (red) line is the result of a magnetic angle scan, in steps of 2.5${}^{ˆ}$. The dashed (blue) lines are the theoretical results at the same energy except at 5.5 eV, where calculated results at 5.4 eV (dash-dotted cyan lines) and 5.6 eV (dashed blue lines) are shown.

Figure 8

Measured (red circles) and calculated (red solid curve) integral elastic cross sections, along with the measured (green squares) and calculated (green dashed curve) momentum-transfer cross sections.