Extracting Electron-Ion Differential Scattering Cross Sections for Partially Aligned Molecules by Laser-Induced Rescattering Photoelectron Spectroscopy

We extract large-angle elastic differential cross sections (DCSs) for electrons scattering from partially aligned ${\mathrm{O}}_2^{+}$ and ${\mathrm{CO}}_2^{+}$ molecules using rescattering photoelectrons generated by infrared laser pulses. The extracted DCSs are in good agreement with those calculated theoretically, demonstrating that accurate DCSs for electron-ion scattering can be extracted from the laser-induced rescattering spectra, thus paving the way for dynamic imaging of chemical reactions by rescattering photoelectron spectroscopy.

Figure 1

Laser-induced two-dimensional RPS spectrum for ${\mathrm{CO}}_2^{+}$, at a laser intensity of $1.3\times {10}^{14}\mathrm{W}/{\mathrm{cm}}^2$. The intensity is plotted in logarithmic false color scale. The polarization direction of the linearly polarized lasers is along the $z$ axis. The elastic scattering of a returning electron with momentum ${\mathbf{p}}_r$ is represented by an arc about the shifted center from the origin by $A_0=p_r/1.26$. See text.

Figure 2

Experimental and theoretical elastic differential cross sections for scattering of free electrons from partially aligned ${\mathrm{O}}_2^{+}$ and ${\mathrm{CO}}_2^{+}$. The experimental data were normalized to the theoretical results at ${\theta }_r=160°$. The theoretical results were obtained by a convolution with MO-ADK angle-dependent ionization rates. To smooth out the ATI peaks, the experimental DCSs are obtained by averaging the raw data over a bin of $\Delta p_r=0.1\mathrm{a}.\mathrm{u}.$ and $\Delta {\theta }_r=10°$.