X-ray waveguide fluorescence holography for thin film and surface structures

X-ray fluorescence holography in (a) normal mode, (b) inverse mode, and (c) waveguid mode

We introduced X-ray waveguide fluorescence holography (XWFH) based on the waveguiding properties of thin films for probing nanostructures and their kinetics. For the structural reconstruction, we developed a rigorous dynamical-scattering based model-independent algorithm, where the structural profile and its confident intervals are estimated with an efficient Markov-Chain Monte Carlo sampler analogous to the Hamiltonian dynamics in classical mechanics.  

Zhang Jiang, et al., Reconstruction of evolving nanostructures in ultrathin films with X-ray waveguide fluorescence holography, Nature Communications 11, 3197 (2020)

DOE Science Highlight: Watching the Evolution of Nanostructures in Thin Films

Nanostructured polymer films with metal-like thermal conductivity

(a) Thermally insulative bulk polymers have disordered and entangled chains. (b) Thermally conductive polymers have ordered and disentangled chains.

Polymers continue to infiltrate into modern technologies ranging from microelectronics to Dreamliner airplanes, thanks to their unique combination of properties not available from other materials. They are lightweight and easy to process. Traditional polymers are also thermal insulators, a characteristic greatly desired for the Styrofoam coffee cup. But it is quite a nuisance for the microelectronic industry, etc., because undissipated heat causes undesirable overheating and harms the device performance.

Continue reading on "Behind the Paper" in the Nature Community.

Yanfei Xu etc, Nanostructured polymer films with metal-like thermal conductivity, Nature Communications 10, 1711 (2019)

MIT spotlight news: New polymer films conduct heat instead of trapping it

Onion model: form factor of core-shell spheroid

Introduction

Spheroid is often used to model particle shapes in small-angle X-ray or neutron scattering modeling. If the particle consists of a core wrapped within a thin shell, one needs to adopt the core-shell spheroid model. Here we will generalize the simple core-shell model to a multi-layered model (onion model). This model can then be used to calculate SAXS or SANS intensities from spheroidal objects with radially continuous density profiles. The majority of this post can be found in the following paper:

Z. Jiang and W. Chen, Generalized skew-symmetric interfacial probability distribution in reflectivity and small-angle scattering analysis J. App. Cryst. 50, 1653-1663 (2017)

LineFit: Matlab toolbox for 1D line fitting

LineFit is a toolbox for 1D line fitting. It is part of the GIXSGUI analysis tools but can run independently on its own. In addition to over 30 built-in curve models, it allows a combination of built-in models or customization of new models. As a class object, LineFit's properties and methods allow one to customize fitting options, easily switch on/off parameters for fitting, evaluate models, and calculate model properties. It provides both script mode for batch processing and GUI mode for interactive fitting. LineFit is tested on Matlab 2015b or later. It requires Matlab Optimization Toolbox for lsqcurvefit solver.

List of built-in curve models:

'1: Cauchy/Lorentzian'	'13: Voigt'	'25: Log-Cauchy'
'2: Intermeidate Lorentzian'	'14: Skew-Laplace'	'26: Log-Normal'
'3: Modified Lorentzian'	'15: Skew-Logistic'	'27: Pareto Type I'
'4: Gaussian'	'16: Skew-Normal'	'28: Weibull'
'5: Generalized Normal 1'	'17: Skew-Pseudo-Voigt (SB)'	'29: Atan'
'6: Laplace'	'18: Skew-Pseudo-Voigt (SSG)'	'30: Error'
'7: Logistic'	'19: Burr XII'	'31: Power Law'
'8: PearsonVII'	'20: Exponential'
'9: Pseudo-Voigt (TCH)'	'21: Gamma'
'10: Pseudo-Voigt (IAT)'	'22: Inverse Gamma'
'11: Pseudo-Voigt (LLHGD)'	'23: Inverse Normal'
'12: Uniform'	'24: Levy'

Download link: linefit

Nanoparticle Sheets That Curl Right Up

Hydrophobic ligands of a nano-particle sheet redistribute unevenly when the sheet is formed on a water surface. This leads to a small but significant ~6 Å difference in average ligand-shell thickness between the two faces of the sheet, as measured by Grazing-incidence X-ray small-angle scattering (GISAXS) at beamline Sector 8-ID-E, the Advanced Photon Source (see the paper by Jiang et al, for details about the beamline). This tiny structural asymmetry is preserved when the underneath water is removed; hence it causes a stress asymmetry, if an electron beam hits the sheet and bonds the ligand molecules. The sheet therefore curves up but always to one side, the originally water-facing side.

Z. Jiang, J. He, S. A. Deshmukh, P. Kanjanaboos, G Kamath., Y. Wang, S. Sankaranarayanan, J. Wang, H. M. Jaeger, and X.-M. Lin, Subnanometre ligand-shell asymmetry leads to Janus-like nanoparticle membranes. Nature Mater. 14, 912-917 (2015). DOI:10.1038/nmat4321

In the News

• Argonne press release
• R&D Magazine
• Gizmodo
• nanowerk
• DOE science highlight 

REFRAC: a toolbox to calculate X-ray refraction of matter

This Matlab toolbox calculates the refraction properties of a matter under X-ray radiation (energy range 0.03~30 KeV), such as dispersion, absorption parts of the index of refraction, the critical angle of total external reflection, attenuation length etc. It basically does the same thing as CXRO X-Ray Interactions With Matter. However, the advantage is that the toolbox does not require internet access, and you can directly use it in your Matlab script.

Caution: CXRO includes Compton scattering when calculating the absorption length, while Refrac does not. The difference becomes obvious for materials of light elements when energy is >10 Kev.

For example, the following script plots dispersion and absorption of SiO2 for X-ray energies between 0.1-10 KeV:

   >>x = 10.^linspace(log10(0.1), log10(10), 1000);           % list of X-ray energies (KeV)
   >>y = refrac('SiO2', x, 2.648);                                         % give chemical formula and mass density to calculate properties of SiO2
   >>loglog(x*1000, y.dispersion, x*1000, y.absorption);    % plot in eV

This standalone toolbox is included in GIXSGUI toolbox. However, you can download and run it separately. After downloading, remember to choose "Add with Subfolders" in Matlab "Set Path" to include the main and all subfolders to Matlab search path; otherwise, the toolbox will not work.

Download: xrayrefraction.zip

For more information about X-ray interactions with matter, go to NIST and LBL. 

GIXSGUI 1.7 released

Update (August 23, 2019): release 1.7.3 GIXSGUI can be download from GitHub: https://github.com/ennogra/GIXSGUI  

Update (October 29, 2016): release 1.7

Update (May 08, 2016): release 1.6.4
 
Update (June 01, 2015): Paper describing the software was published. You may download here DOI:10.1107/S1600576715004434 or drop me an email to request a copy. GIXSGUI: a Matlab toolbox for grazing-incidence X-ray scattering data visualization and reduction, and indexing of buried 3D periodic nanostructured films. J. Appl. Crystallogr. 48, 917-926 (2015).  Abstract: GIXSGUI is a MATLAB toolbox that offers both a graphical user interface and script-based access to visualize and process grazing-incidence X-ray scattering data from nanostructures on surfaces and in thin films. It provides routine surface scattering data reduction methods such as geometric correction, one-dimensional intensity linecut, two-dimensional intensity reshaping, etc. Three-dimensional indexing is also implemented to determine the space group and lattice parameters of buried organized nanoscopic structures in supported thin films.

Update (March 07, 2015): the compatibility problem with 2014b has been solved. 

Download GIXSGUI here: https://www.aps.anl.gov/Sector-8/8-ID/Operations-and-Schedules/Useful-Links/Sector-8-GIXSGUI