Retrieval of electron-atom scattering cross sections from laser-induced electron rescattering of atomic negative ions in intense laser fields

We investigated the two-dimensional electron momentum distributions of atomic negative ions in an intense laser field by solving the time-dependent Schrödinger equation (TDSE) and using the first- and second-order strong-field approximations (SFAs). We showed that photoelectron energy spectra and low-energy photoelectron momentum distributions predicted from SFAs are in reasonable agreement with the solutions from the TDSE. More importantly, we showed that accurate electron-atom elastic scattering cross sections can be retrieved directly from high-energy electron momentum spectra of atomic negative ions in the laser field. This opens up the possibility of measuring electron-atom and electron-molecule scattering cross sections from the photodetachment of atomic and molecular negative ions by intense short lasers, respectively, with temporal resolutions in the order of femtoseconds.

Figure 1

(Color online) Energy spectra of laser-induced photoelectrons of ${\text{H}}^{-}$ obtained from TDSE and SFA. The laser parameters are $I=1.0\times {10}^{11}\text{W}/{\text{cm}}^2$ and $\lambda =10600\text{nm}$ for a pulse with three optical cycles (see text).

Figure 2

(Color online) 2D momentum distributions of laser-induced photoelectrons of ${\text{H}}^{-}$ in the low-energy region, obtained from TDSE (a) and from SFA (b). The horizontal axis is the electron momentum along the direction of laser polarization and the vertical axis is any axis perpendicular to it (the electron spectrum has cylindrical symmetry.) The laser parameters are the same as in Fig. 1.

Figure 3

(Color online) Angular distributions of laser-induced photoelectrons of ${\text{H}}^{-}$, generated by a laser with wavelength $\lambda =2150\text{nm}$. (a) Intensity $I=1.3\times {10}^{11}\text{W}/{\text{cm}}^2$ for electron energy $E=0.34\text{eV}$. (b) Intensity $I=6.5\times {10}^{11}\text{W}/{\text{cm}}^2$ for electron energy $E=0.12\text{eV}$. The experimental data are from Reichle et al. [3].

Figure 4

(Color online) (a),(b) 2D momentum distributions of laser-induced photoelectrons of ${\text{H}}^{-}$ in the high-energy region, obtained from TDSE and SFA, respectively. The laser parameters are the same as in Fig. 1. (c) The electric field and the vector potential of a three-cycle pulse with the “born time” of the detached electron and its return time indicated. (d) Electron yields along the BRR from the TDSE calculations compared to the electron-H elastic scattering cross sections, and the corresponding results from the SFA compared with the FBA.

Figure 5

(Color online) TDSE results for single ionization of ${\text{F}}^{-}$ in a three-cycle laser pulse with $\lambda =1800\text{nm}$ and $I=1.3\times {10}^{13}\text{W}/{\text{cm}}^2$. (a) Energy spectra, (b) 2D electron momentum distributions in the high-energy region, (c) electron yields along the BRR compared to the electron-F elastic scattering cross sections.