Continuum-distorted-wave eikonal-initial-state description of the electron-impact ionization of ${\mathrm{H}}_2\mathrm{O}$ at low impact energies

Fully differential cross sections for electron impact of gaseous ${\mathrm{H}}_2\mathrm{O}$ at an impact energy of 81 eV are calculated within the framework of the continuum-distorted-wave eikonal-initial-state model. Present results are benchmarked against recent experimental data obtained in MPIK-Heidelberg by means of a reaction microscope. Cross sections calculated for different molecular orientations are properly averaged to mimic the experimental conditions. Present results are in very good agreement with the experimental data for coplanar geometries. For the denominated perpendicular emission planes the agreement tends to deteriorate as the projectile momentum transfer increases.

Figure 1

Electron emission planes considered in this work: (a) collision plane xz, (b) semiperpendicular plane yz, and (c) full perpendicular plane xy. Both angles ${\theta }_1$ and ${\theta }_2$ were taken as positive counterclockwise.

Figure 2

CDW-EIS triply differential cross section for electron-impact ionization of $1b_1$ and $3a_1$ orbitals of ${\mathrm{H}}_2\mathrm{O}$. The impact energy is 81 eV. Emission energies and projectile scattering angles are indicated in the insets. Experimental and DWBA data from Ref. [13] scaled to the present theoretical results. Results shown are for the scattering plane xz [Fig. 1].

Figure 3

Same as Fig. 2, but for the semiperpendicular plane yz [Fig. 1].

Figure 4

Same as Fig. 2. but for the full perpendicular plane xy [Fig. 1].