scholarly journals Brownian and advective dynamics in microflow studied by coherent X-ray scattering experiments

2016 ◽  
Vol 23 (6) ◽  
pp. 1401-1408 ◽  
Author(s):  
Raphael Urbani ◽  
Fabian Westermeier ◽  
Benjamin Banusch ◽  
Michael Sprung ◽  
Thomas Pfohl
Keyword(s):  
Correlation Functions ◽  
Brownian Dynamics ◽  
Flow Behavior ◽  
Colloidal Suspensions ◽  
Single Scattering ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Advective Flow ◽  
X Ray ◽  
Auto Correlation

Combining microfluidics with coherent X-ray illumination offers the possibility to not only measure the structure but also the dynamics of flowing samples in a single-scattering experiment. Here, the power of this combination is demonstrated by studying the advective and Brownian dynamics of colloidal suspensions in microflow of different geometries. Using an experimental setup with a fast two-dimensional detector and performing X-ray correlation spectroscopy by calculating two-dimensional maps of the intensity auto-correlation functions, it was possible to evaluate the sample structure and furthermore to characterize the detailed flow behavior, including flow geometry, main flow directions, advective flow velocities and diffusive dynamics. By scanning a microfocused X-ray beam over a microfluidic device, the anisotropic auto-correlation functions of driven colloidal suspensions in straight, curved and constricted microchannels were mapped with the spatial resolution of the X-ray beam. This method has not only a huge potential for studying flow patterns in complex fluids but also to generally characterize anisotropic dynamics in materials.

Multiple-scattering effects in SAXS and XPCS measurements in the ultra-small-angle region

2018 ◽  
Vol 51 (3) ◽  
pp. 706-713 ◽  
Author(s):  
Enrico F. Semeraro ◽  
Johannes Möller ◽  
Theyencheri Narayanan
Keyword(s):  
Multiple Scattering ◽  
Small Angle ◽  
Colloidal Suspensions ◽  
Single Scattering ◽  
Correlation Spectroscopy ◽  
Acquisition Time ◽  
Experimental Conditions ◽  
X Ray ◽  
Beneficial Effects ◽  
Counting Statistics

An experimental study of the influence of multiple-scattering events on data acquired by small-angle X-ray scattering (SAXS) and X-ray photon correlation spectroscopy (XPCS) techniques in the ultra-small-angle range is presented. Both techniques rely on the single-scattering assumption and any deviation may lead to erroneous interpretation of structural and dynamical results. Typical effects of multiple scattering on measured static and dynamic scattering from model colloidal suspensions are presented, and it is demonstrated that the same information content as in a single-scattering experiment can be extracted after applying appropriate corrections. The perturbations induced by multiple scattering on resolution, photon statistics and speckle visibility are evaluated and the required optimal experimental conditions are discussed. In many cases, multiple scattering might be tolerable to a certain extent, especially if any shortcomings are outweighed by beneficial effects from counting statistics, acquisition time and signal-to-background ratio. The presented study may help to optimize future experiments and serve as a guide for data evaluation for this type of system.

scholarly journals On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

2017 ◽  
Vol 50 (2) ◽  
pp. 357-368 ◽  
Author(s):  
Oier Bikondoa
Keyword(s):  
Correlation Functions ◽  
Photon Correlation Spectroscopy ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
Time Correlation Functions ◽  
Spectroscopy Data ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Processes ◽  
Time Correlations

Multi-time correlation functions are especially well suited to study non-equilibrium processes. In particular, two-time correlation functions are widely used in X-ray photon correlation experiments on systems out of equilibrium. One-time correlations are often extracted from two-time correlation functions at different sample ages. However, this way of analysing two-time correlation functions is not unique. Here, two methods to analyse two-time correlation functions are scrutinized, and three illustrative examples are used to discuss the implications for the evaluation of the correlation times and functional shape of the correlations.

Simulations of Co-GISAXS during kinetic roughening of growth surfaces

2017 ◽  
Vol 24 (6) ◽  
pp. 1187-1194 ◽  
Author(s):  
Mahsa Mokhtarzadeh ◽  
Karl F. Ludwig
Keyword(s):  
Structure Factor ◽  
Correlation Functions ◽  
Growth Models ◽  
Temporal Correlation ◽  
Grazing Incidence ◽  
Correlation Spectroscopy ◽  
Surface Growth ◽  
X Ray ◽  
Kinetic Roughening ◽  
Growth Equations

The recent development of surface growth studies using X-ray photon correlation spectroscopy in a grazing-incidence small-angle X-ray scattering (Co-GISAXS) geometry enables the investigation of dynamical processes during kinetic roughening in greater detail than was previously possible. In order to investigate the Co-GISAXS behavior expected from existing growth models, calculations and (2+1)-dimension simulations of linear Kuramoto–Sivashinsky and non-linear Kardar–Parisi–Zhang surface growth equations are presented which analyze the temporal correlation functions of the height–height structure factor. Calculations of the GISAXS intensity auto-correlation functions are also performed within the Born/distorted-wave Born approximation for comparison with the scaling behavior of the height–height structure factor and its correlation functions.

Condensed Exponential Correlation Functions in Multicomponent Polymer Blends Measured by X-ray Photon Correlation Spectroscopy

2006 ◽  
Vol 39 (25) ◽  
pp. 8822-8831 ◽  
Author(s):  
Megan L. Ruegg ◽  
Amish J. Patel ◽  
Suresh Narayanan ◽  
Alec R. Sandy ◽  
Simon G. J. Mochrie ◽  
...  
Keyword(s):  
Polymer Blends ◽  
Correlation Functions ◽  
Photon Correlation Spectroscopy ◽  
Correlation Spectroscopy ◽  
Photon Correlation ◽  
X Ray ◽  
Multicomponent Polymer

scholarly journals First experimental feasibility study of VIPIC: a custom-made detector for X-ray speckle measurements

2016 ◽  
Vol 23 (2) ◽  
pp. 404-409 ◽  
Author(s):  
Abdul K. Rumaiz ◽  
D. Peter Siddons ◽  
Grzegorz Deptuch ◽  
Piotr Maj ◽  
Anthony J. Kuczewski ◽  
...  
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Relaxation Times ◽  
Colloidal Suspensions ◽  
Correlation Spectroscopy ◽  
Polystyrene Latex ◽  
High Time Resolution ◽  
Photon Correlation ◽  
X Ray ◽  
Event Stream ◽  
Custom Made

The Vertically Integrated Photon Imaging Chip (VIPIC) was custom-designed for X-ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time- and position-stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non-zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame-oriented detectors such as charge-coupled devices or conventional hybrid pixel detectors. This feature allowscontinuousacquisition of data with timescales from microseconds to hours. In this work VIPIC has been used to measure X-ray photon correlation spectroscopy data on polystyrene latex nano-colliodal suspensions in glycerol and on colloidal suspensions of silica spheres in water. Relaxation times of the nano-colloids have been measured for different temperatures. These results demonstrate that VIPIC can operatecontinuouslyin the microsecond time frame, while at the same time probing longer timescales.

Hydroxyl Changing Mechanism of Cotton Cellulose during Alkaline Treatment Characterized by ATR-FTIR in Combination with Two-Dimensional Correlation Spectroscopy

2020 ◽  
Vol 7 (5) ◽  
pp. 1-8
Author(s):  
Bolin Ji ◽  
Zijing Cai ◽  
Gang Sun ◽  
Kelu Yan
Keyword(s):  
Molecular Spectroscopy ◽  
Alkaline Treatment ◽  
Attenuated Total Reflection ◽  
Correlation Spectroscopy ◽  
Cotton Cellulose ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modeling Analysis ◽  
Naoh Solution

Hydroxyl changes of cotton cellulose treated with sodium hydroxide (NaOH) solution is closely related with hydrogen bonding (H-bonds) between different hydroxyls, which is difficult to directly measure by common instrumentational methods of X-ray diffraction (XRD) or Fourier transform infrared (FTIR) spectroscopy. Two-dimensional correlation spectroscopy (2Dcos) is a powerful tool to analyze the changes of molecular spectroscopy. In this study, the alkaline- treated cotton cellulose was monitored in real time by attenuated total reflection (ATR) in combination with 2Dcos. Results indicated that the H-bonds changed in the following sequence order: ν(O3–H3...O5) (intramolecular) → ν(O6–H6...O3') (intermolecular) → ν(O2–H2...O6) (intramolecular). Moreover, Gaussian computational modeling analysis also confirmed this mechanism. Both XRD and FTIR results indicated the decrease of crystallinity of the alkaline-treated cotton cellulose over prolonged time.

Sign in / Sign up

Export Citation Format

Share Document