ABSTRACT
This chapter examines measurements that use charged particles instead of light as the probe. It considers probing quantum dynamics using either electron or X-ray diffraction from a molecular sample that has been excited by a pump pulse. The chapter also considers time-resolved diffractive measurements from one-dimensional systems, beginning with experiments using electrons and followed by similar experiments with X-rays. Interpretation of the data in diffractive measurements is not as straightforward as with optical probes. The experimental arrangements are quite similar for both electron and X-ray diffraction. A pump pulse initiates dynamics by launching a vibrational wave packet in an excited electronic state of the molecule. A primary advantage of probing with electron or X-ray diffraction is that it provides a more direct measure of time-dependent changes in molecular structure than optical probes. This is particularly important for larger molecules.
