Sketch of the experimental setup.

<p>The experimental arrangement for time-resolved X-ray measurements at the Austrian SAXS–beamline at the ELETTRA synchrotron light source is shown. For T-jump experiments, an erbium laser beam (IR), wavelength λ = 1.5 µm, was directed via a prism onto the sample capillary which was thermostated with a Peltier unit. Laser pulse energy was 2 J within 2 ms resulting in an average T-jump amplitude of 10–12°C. The exposure time was 10 ms per frame. For T-drop experiments, the empty X-ray capillary was pre-cooled in a stream of nitrogen adjusted to −20°C. LDL samples, preheated to approx.10°C above the melting transition, were injected by a motor-driven syringe. A drop in temperature of about 20°C could be induced in about 3–4 s. The exposure time was 250 ms per frame.</p

Time-resolved nanophase transition in LDL.

<p>The rise in the integrated intensity of the 1st side-maximum upon laser jump is shown as a function of time (A). The time slicing was 10 ms per image. The time point of laser flash is set to zero seconds. The error function of statistical variation displays a maximum inaccuracy in time of about 5 ms. Thus, the offset in transition is much shorter than the sampling time of 10 ms and the 2 ms of laser flash. The integrated intensities of the 1st side-maximum obtained by static measurements within a temperature range of 0°C and 50°C with a step width of 5°C (B, left panel) are correlated to the time-course of integrated intensities of the 1st side-maximum obtained by dynamic measurements (B, right panel). For static measurements, a measuring time of 30 s and an equilibration time of 10 minutes at each temperature was chosen. For dynamic measurements, the measuring time per frame was 250 ms. A half-time of 2 seconds, corresponding to a temperature drop of about 10°C, could be achieved to pass through the transition temperature. The decline in integrated intensity strictly followed the drop in temperature. Tm for the LDL sample shown was about 22°C, as determined by microcalorimetry.</p