Figure 1
(a) Schematic of a laser pump/X-ray probe experiment on a multi-lamellar lipid stack, in the conventional set-up of low-frequency filling modes, by use of choppers/gating detectors. The temporal evolution of the specular and diffuse scattering is recorded to obtain information about the structural dynamics on a molecular scale in response to short pulse excitation. (b) Schematic of the operating principle of single-photon-counting detectors (row 1–3). A single-channel analyzer (SCA) discriminates events from background noise; individual events are counted in a binary fashion. Stroboscopic experiments at fpp = 1 kHz (row 4) smaller than the synchrotron pulse frequency fb ≃ 31 MHz (row 1) are necessarily accompanied by a tremendous loss in the effective X-ray intensity due to fast gating or mechanical pulse selection as indicated by grey shading. |