X-ray photon correlation spectroscopy using a fast pixel array detector with a grid mask resolution enhancer.

Taiki Hoshino,Hiroshi Jinnai,Yoshihito Tanaka,Koji Mitamura,Masaki Takata,Moriya Kikuchi,Kiminori Ito,Sono Sasaki,Atsushi Takahara,Daiki Murakami,Yoshiko Harada

doi:10.1107/s0909049512038769

Abstract

The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy (XPCS) measurements to investigate fast dynamics on a microscopic scale. A detecting system, in which each pixel of a single-photon-counting pixel array detector, PILATUS, is covered by grid mask apertures, was constructed for XPCS measurements of silica nanoparticles in polymer melts. The experimental results are confirmed to be consistent by comparison with other independent experiments. By applying this method, XPCS measurements can be carried out by customizing the hole size of the grid mask to suit the experimental conditions, such as beam size, detector size and sample-to-detector distance.

Highlights

X-ray photon correlation spectroscopy (XPCS) uses partially coherent X-rays to provide experimental access to a variety of microscopic dynamic phenomena (Grubel et al, 2008)
The same procedure was not applied in the present system, where the hole sizes of the grid mask are not strictly uniform and vary with a standard deviation of 3.69 mm, and the baseline obtained by considering the limit t ! 1 is always larger than unity without physical meaning
From the static SAXS measurements the static structure factor S(q) was obtained, which has local maxima where À(q) has local minima as shown in the inset of Fig. 7. These results indicate that the XPCS measurements successfully observed so-called ‘de Gennes narrowing’, which is a generic feature of diffusing particles in concentrated

Summary

Introduction

X-ray photon correlation spectroscopy (XPCS) uses partially coherent X-rays to provide experimental access to a variety of microscopic dynamic phenomena (Grubel et al, 2008). For measurements up to the high-q region, shortening the sample-to-detector distance is one of the most effective solutions This modification is expected to make XPCS measurements difficult because the speckle size decreases with decreasing distance; a higher spatial resolution is required in 2D detectors. To overcome this problem a method using a grid mask with small holes, which enables measurement up to high-q regions, is proposed in this.

Experimental

Evaluation of the measured time-autocorrelation function

Demonstration of measurements in the X-ray region

Conclusion