Coherent X-Ray Diffraction Imaging Experiment at SACLA on Au Nanoparticles in a Micro-Liquid Enclosure
Po-Nan Li1*, Chi-Feng Huang1,2, Yasumasa Joti3, Yoshitaka Bessho1, Takashi Kimura4, Yoshinori Nishino4, Yeu-Kuang Hwu1, Keng S. Liang1, Ting Kuo Lee1
1Institute of Physics, Academia Sinica, Taipei, Taiwan
2Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
3Japan Synchrotron Radiation Research Institute/Spring-8, Hyogo, Japan
4Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
* presenting author:李柏南, email:pnli@phys.sinica.edu.tw
With extremely brilliant pulses, the X-ray free-electron laser (XFEL) has enabled the investigation of structures of weak and small objects such as nano-particles or biological samples. While gold nano-particles (GNPs) are widely employed in the labeling of cells and proteins for image enhancement, in this work we study the coherent diffraction imaging (CDI) of mixture of streptavidin conjugated 5 nm and 40 nm Au nanoparticles, which was enclosed in a micro-liquid enclosure. The CDI experiment was performed at SACLA, Japan’s X-ray free-electron laser, with 10-femto second pulses of 4,000 eV X-ray. Hundreds of diffraction patterns were collected, from which several distinctive ones are reconstructed and investigated. Pictures of selected patterns will be presented on the poster.

The recorded diffraction patterns were phased by using guided hybrid input-output (GHIO) algorithm, giving us the reconstructed images of GNPs, and the images with dimeric or trimeric aggregate were selected for further study. Thanks to the known photon flux of the coherent beam, we are able to quantitatively analyze the density of these GNP aggregates. We also perform numerical experiments to validate those images. We find consistent result between the model simulation and experimental data. Similar aggregates were also found in the TEM images of the same batch of sample, again showing that our reconstructions are reasonably accurate.

This study would help us understand more about the correlation of Au nano-particles in the CDI of XFEL and can therefore facilitate our future data analysis of Au-labeled biological samples. Details and discussion will be given on the poster.


Keywords: coherent diffraction imaging, free-electron lasert, X-ray, gold nano-particle, interference