Hard X-Ray Photon Correlation Spectroscopy Methods for Materials Studies

Abstract

Understanding and designing sophisticated new materials require measurements of not only their average structural properties but also their dynamic behavior. X-ray photon correlation spectroscopy (XPCS) provides this information by characterizing fluctuations in condensed matter across a broad range of length scales and timescales. Over the past two decades, XPCS has provided a wide variety of results in the study of materials properties. In this review, we provide an overview of coherence, photon correlation spectroscopy, and the dynamic structure factor as well as information on the mechanics of XPCS experiments. We highlight the impact that this infrastructure has had on materials research and the bright future that is forthcoming with the anticipated upgrade of many third-generation synchrotron sources to fourth-generation multibend achromat sources.

Towards molecular movies with X-ray photon correlation spectroscopy

“…The advancing XFELs feature super-conducting accelerator technologies which boost further the brilliance of the current XFEL sources reaching MHz repetition rates. [5][6][7][8] X-ray Photon Correlation Spectroscopy (XPCS) [9][10][11][12][13][14][15][16] is a coherent scattering technique that benefits particularly from this increase in coherent flux holding the potential of capturing structural dynamics at variable length scales, ranging from the nanoscale down to atomic scales. [17][18][19][20] One distinct advantage of XPCS experiments employing the new X-ray sources is the possibility to study dynamics in transient samples (e.g., deeply supercooled water) which are only stable for a short period of time.…”

The Effect of Intensity Fluctuations on Sequential X-ray Photon Correlation Spectroscopy at the X-ray Free Electron Laser Facilities

“…with τ = 1/(DQ 2 ). These expressions indicate that the characteristic time constant τ and the speckle visibility parameter β can be determined via a two-parameter least-squares fit to the data points of the ∆t-dependent g 2 function obtainable from experimental data at a given Q, as is commonly done in XPCS analysis [14].…”

“…X-ray photon correlation spectroscopy (XPCS) has recently emerged as a tool for capturing the dynamics of structural evolution in materials and molecular assemblies [12][13][14]. Coherent X-ray photons scattered by the material produce a speckle pattern in the far field, which is the Fourier transform of all the diffracting features within the beam footprint.…”

Focusing a round coherent beam by spatial filtering the horizontal source

“…Synchrotron light sources produce partially coherent light that has enabled new techniques such as X-ray photon correlation spectroscopy (XPCS) to flourish into mature material characterization methods (Sutton, 2008;Livet & Sutton, 2012;Sinha et al, 2014;Sandy et al, 2018). Due to the large mismatch between the horizontal and vertical source size in third-generation synchrotron sources, which is typically a factor of 20 larger in the horizontal direction, the coherence length is a factor of 20 smaller in the horizontal than in the vertical direction.…”