Schematic diagram of x-ray speckle intensity correlation spectroscopy system using a Michelson type delay pulse generator and a soft x-ray streak camera. M, SM, OS, and BS represent a normal incident Mo/Si multilayer mirror, a normal incident Mo/Si multilayer SM, an optical shutter, and a soft x-ray BS, respectively. All the optical components which compose the present spectroscopy system are set in a vacuum because the wavelength of the x-ray lasing is in the soft x-ray region. The delay time of the second x-ray pulse from the first x-ray pulse can be manipulated by changing the delay path length between the BS and the M1 mounted on the precision motorized linear stage. Driving of the x-ray streak camera is perfectly synchronized with x-ray lasing and x-ray pulse illumination onto the sample by the direct drive technique using the precision master clock.
Photograph of the Michelson type delay pulse generator. The x-ray mirrors are mounted on the motorized mirror mounts, and the motorized optical shutters are placed in front of them. The mirrors and the shutters can be manipulated with a computer. All components are placed in the vacuum chamber.
(a) X-ray streak camera image of x-ray speckles of . (b) The x-ray intensity profiles of them in the horizontal direction. The x-ray streak image shown in Fig. 3(a) was obtained at the sample temperature of 405 K and the delay time of 15 ps. The vertical direction is the time evolution of the speckles and the horizontal direction is the scattering angle . The photocathode length of the x-ray streak camera and the pixel number of streak image in the horizontal direction are 11 mm and 672 channels, respectively. The parallel direction of Fig. 3(b) is the scattering angle.
Decay curves of as a function of delay time at several sample temperatures from 2 K below Tc up to 10 K above Tc . (a) and (b) were independently obtained in the first experiment and in the second experiment, respectively. The inset of Fig. 4(a) shows the profile around the specular reflection signal obtained at the sample temperature of 399 K and the delay time of 15 ps. The solid lines are the fitting results with the Eq. (2) by means of the least-square method.
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