Oscillation of the electron-density distribution in momentum space: An $(e,2e)$ study of ${\mathrm{H}}_2$ at large momentum transfer

Bond oscillation, a phenomenon characteristic of the molecular electron-density distribution in momentum space, is demonstrated for the $1{\sigma }_g$ molecular orbital of ${\mathrm{H}}_2$ with an ($e$, $2e$) experiment at large momentum transfer. Analysis of the experimental data in terms of two-center interference effects has revealed that different oscillatory structures can be observed, depending on the model for describing ($e$, $2e$) ionization from the constituent H $1s$ atomic orbitals. It is shown that bond oscillation is highly sensitive to the spatial pattern and chemical bonding nature of the molecular orbital.

Figure 1

Δϕ-angle integrated binding energy spectrum of ${\mathrm{H}}_2$.

Figure 2

Comparison of experimental and theoretical momentum profiles for the ${\left(1{\sigma }_g\right)}^{-1}$ ionization transition of ${\mathrm{H}}_2$.

Figure 3

(a) Theoretical momentum profiles for the ${\left(1s\right)}^{-1}$ ionization transition of H and He. (b) Comparison of experimental, theoretical, and analytical interference factors for bond oscillation of ${\mathrm{H}}_2$. See text for details.