Attosecond Time-Resolved Imaging of Molecular Structure by Photoelectron Holography

Dynamic imaging of the molecular structure of ${\mathrm{H}}_2^{+}$ is investigated by attosecond photoelectron holography. The interference between direct (reference) and backward rescattered (signal) photoelectrons in attosecond photoelectron holography reveals the birth time of both channels and the spatial information of molecular structure. This is confirmed by simulations with a semiclassical model and numerical solutions of the corresponding time-dependent Schrödinger equation, suggesting an attosecond time-resolved way of imaging molecular structure obtained from laser induced rescattering of ionized electrons. It is shown that both short and long rescattered electron trajectories can be imaged from the momentum distribution.

Figure 1

Schematic illustration of interference trajectories in APH of ${\mathrm{H}}_2^{+}$. $A$ is the rescattering channel, its short and long trajectories will interfere with the direct ionization channels of $B$ and $C$, respectively. Introducing multicenter molecular structure, channel $A$ may be rescattered by the parent core or its neighboring core. Channels $B$ ($B^{\prime }$) and $C$ ($C^{\prime }$) may come from different centers.

Figure 2

Photoelectron angular momentum distribution of ${\mathrm{H}}_2^{+}$ from the semiclassical model [(a) and (b)] and TDSE (c). (a) represents the short trajectory, while (b) stands for the long trajectory. The initial state is the ground $1s{\sigma }_g$ state. The internuclear distance $R=2\mathrm{a}.\mathrm{u}.$ The laser intensity is $I=1.5\times {10}^{15}\mathrm{W}/{\mathrm{cm}}^2$, wavelength is 532 nm ($T_0=1.8\mathrm{fs}$). The molecular axis is along $x$ axis, perpendicular to the laser polarization direction $z$. In (a) and (b), the left and right panels correspond to the photoelectron rescattered by the parent or the neighboring ions, respectively. In (c), the color is plotted on the logarithmic scale.

Figure 3

The same as Fig. 2, but the molecular axis is parallel to the laser polarization $z$ axis.