Dynamics of colloidal crystals studied by pump-probe experiments at   FLASH
  We present a time-resolved infrared (IR) pump and extreme-ultraviolet (XUV) probe diffraction experiment to investigate ultrafast structural dynamics in colloidal crystals with picosecond resolution. The experiment was performed at the FLASH facility at DESY with a fundamental wavelength of 8 nm. In our experiment, the temporal changes of Bragg peaks were analyzed and their frequency components were calculated using Fourier analysis. Periodic modulations in the colloidal crystal were localized at a frequency of about 4-5 GHz. Based on the Lamb theory, theoretical calculations of vibrations of the isotropic elastic polystyrene spheres of 400 nm in size reveal a 5.07 GHz eigenfrequency of the ground (breathing) mode. 
R. Dronyak, J. Gulden, O. M. Yefanov, A. Singer, T. Gorniak, T.   Senkbeil, J.-M. Meijer, A. Al-Shemmary, J. Hallmann, D. D....
cond-mat.mtrl-sci