Figure 1: Laser-induced electron diffraction from aligned C2H2 molecules using a mid-infrared OPCPA source and a reaction microscope.
From: Imaging an aligned polyatomic molecule with laser-induced electron diffraction
The cartoon film shows the procedure. (a) The C2H2 molecules are pre-aligned by focusing the 1.7 μm pump pulse (blue) into a molecular jet. (b) The 3.1 μm pulse (red) is used to generate high-energy electrons that subsequently rescatter off the parent ion. (c) The rescattered electrons carry structural information of the parent ion that is contained in the detected angular momentum distributions. The anticollinear electric (E) and magnetic (B) fields guide the charged fragments towards opposing position-sensitive detectors.