Probing Dynamics in Colloidal Crystals with Pump-Probe Experiments at LCLS: Methodology and Analysis

Nastasia Mukharamova,Tatiana Gurieva,Marcin Sikorski,Sanghoon Song,Anatoly Shabalin,Oleg Gorobtsov,Sergey Lazarev,Sergey Lazarev,Sergey Lazarev,Diling Zhu,Yiping Feng,Garth Williams,Garth Williams,Elena Sulyanova,Matthieu Chollet,Marcin Sikorski,Oleksandr Yefanov,Oleksandr Yefanov,Ruslan Kurta,Ruslan Kurta,Andrej Singer,Janne-Mieke Meijer,Janne-Mieke Meijer,Anatoly Shabalin,Ivan Vartanyants,Ivan Vartanyants,Dmitry Dzhigaev

doi:10.3390/app7050519

Abstract

We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL). Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses at an energy of 8 keV with a time delay up to 1000 ps. The positions of the Bragg peaks, and their radial and azimuthal widths were analyzed as a function of the time delay. The spectral analysis of the data did not reveal significant enhancement of frequencies expected in this experiment. This allowed us to conclude that the amplitude of vibrational modes excited in colloidal crystals was less than the systematic error caused by the noise level.

Highlights

Acoustic motion in nanoscale objects induced by light is of importance for both fundamental science and applications
The pump-probe experiments were performed at the Linac Coherent Light Source (LCLS) [9]
The diffraction patterns from the colloidal crystals, which were pumped by laser pulses and probed by X-ray free-electron laser (XFEL) radiation, were collected

Summary

Introduction

Acoustic motion in nanoscale objects induced by light is of importance for both fundamental science and applications. Dynamics in submicrometer colloidal crystals was investigated using different techniques such as Raman scattering [8], Brillouin light scattering [2], and optical pump-probe spectroscopy [4,5,6,7] These methods have limited spatial resolution and are not suitable for the observation of the detailed structure of the sample. The femtosecond X-ray pulses from free-electron laser sources allow an investigation of transient states of time-dependent processes [12,13,14,15,16,17] In this respect, XFELs are especially well suited for investigating ultrafast structural dynamics of colloidal crystals. We present the results of a time-resolved pump-probe diffraction experiment in which the ultrafast dynamics in colloidal crystals induced by an IR laser was investigated.

Experiment

Fourier

Results and Discussion

Conclusions