Figure 2
(a) The 40
M phase (T = 305 K) and 002 R phase (T = 350 K) Bragg reflections measured by 10 keV x-ray radiation. The blue dashed line indicates the incident x-ray Bragg angle θ = 25.62° at which the time-resolved measurements are performed. (b) The M and R diffraction images are measured below and at the transition temperatures by an x-ray area detector. The white arrow points to higher 2θ direction. (c) Diffraction intensities of the M and R phases as a function of delay, measured with a 50 μm (FWHM) x-ray beam (filled symbols) and with a 350 nm x-ray beam (open symbols, see text) at a fluence of 14 mJ/cm2. The open symbols show the averaged diffraction intensity of the 2D maps in Fig. 3 normalized by a detector reading which is proportional to the incident x-ray flux. The purple arrows show the start (t1 = 100 ps, limited by x-ray pulse duration) and the end (t2. see Supplemental Materials) time of the out-of-plane phase progression. (d) Schematics of the out-of-plane progression at two delays. The red and blue regions represent R and M phases respectively.
