Single Molecule Diffraction

For solving the atomic structure of organic molecules such as small proteins which are difficult to crystallize, the use of a jet of doped liquid helium droplets traversing a continuous high energy electron beam is proposed as a means of obtaining electron diffraction patterns (serial crystallography). Organic molecules (such as small proteins) within the droplet (and within a vitreous ice jacket) may be aligned by use of a polarized laser beam. Iterative methods for solving the phase problem are indicated. Comparisons with a related plan for pulsed x-ray diffraction from single proteins in a molecular beam are provided.

Figure 1

Diffraction camera for single-molecule electron diffraction. A continuous electron beam is used. The laser polarization is rotated after each data readout for a new molecular beam orientation. Hydrated organic molecules are picked up within liquid helium droplets to form a molecular beam traversing the electron beam.