The saxslab instrument has the option to be setup to perform grazing incidence small or wide angle xray scattering on samples with nanostructured surfaces. Diffractometer manufacturers typically provide commercial software to be used for xray reflectivity measurements. Stochastic fitting of specular xray reflectivity data. The saxslab instrument is setup to perform transmission small or wide angle xray scattering on freestanding samples, powders prepared in kapton tape, liquids in capillaries and gels in sandwich cells with mica windows. The xray reflectivity has been measured at xray wavelength. It is related to the complementary techniques of neutro. For small samples, the modification of the xray reflectivity xrr profile by the. A calculator for scattering length density that can be used for arbitrary xray energies. Xray reflectivity xray reflectvity uses total external reflection from surfaces and interfaces. However, the calculated results have shown often strange behaviour. Fits neutron and xray reflectivity data using parratt recursion or abeles matrix. Xray reflectivity xrr or xr and neutron reflectivity nr are techniques which measure the intensity of reflected radiation as a function of angle where, by definition for specular reflectivity, the incident.
Iucr fast fitting of reflectivity data of growing thin. Standard training shows how to perform specific alignment for gisaxs measurements with uniformly flat thin film samples by using the specularly reflected xray beam. Parratt surface studies of solids by total reflection of. This simulation program makes use of the parrat formalism for reflectivity 1. Specifically, xrays are used to probe the electron density perpendicular to the surface and thereby obtain information about the surface roughness, thin film thickness and density. Parratt implemented the complete field calculation for the prediction of the reflected part of the beam not only paving the way for xray reflectivity xrr. It is useful for layer thickness between 5 and 350 angstrom. There are many reflectometry programs available for download from the web. The program is able to simulate standard nonmagnetic xray reflectivity for variable energies based upon the so called parratt formalism. In this technique, monochromatic xrays reflected from the sample surface at low incident angles are measured and analyzed with a typical accuracy of. Estimation of surface and interface roughness using xray. Xray and neutron reflectometry are well established analytical techniques for thinfilm metrology. Xpert reflectivity is a software package for displaying, simulating and fitting xray reflectivity curves. In the present study, the xray reflectivity data were fitted using a twoslab model with the parrat32 software braun, 1997 based on the parratt formalism with the thickness, electron density and roughness of the two slabs as parameters.
This can be useful for fitting data from other scattering experiments, or for any other. Reflectivity calculations, modelling and software a bibliography. Nist software for fitting neutron or xray reflectivity curves. How to conduct the batch fitting for xray reflectivity. Neutron reflectometry is a neutron diffraction technique for measuring the structure of thin films, similar to the often complementary techniques of xray reflectivity and ellipsometry. Mirror reflectivity cxro xray interactions with matter. Fitting xray multilayers reflectivities by means of ppm.
Free reflectivity downloads download reflectivity software. Datareduction procedure for correction of geometric factors in. The potential of xray reflectivity xrr is indicated by the abundant studies. The differential evolution algorithm is a robust optimization method which avoids local minima but at same is a highly effective. I hope to conduct the parratt fitting for these data and get the information about the thickness, roughness. Xray reflectivity sometimes known as xray specular reflectivity, xray reflectometry, or xrr is a surfacesensitive analytical technique used in chemistry, physics, and materials science to characterize surfaces, thin films and multilayers.
Xray interactions with matter optical constants lawrence berkeley. It utilizes the parratt recursion formula for simulating specular reflectivity. Fitting xray multilayers reflectivities by means of ppm software d. All the available xrr analysis programs generate the fresnel reflectivity. Reflectivity calculation the refractive index, n, for xray radiation differs only slightly from unity and is given by equation 1. There is also a downloadable app that can be used on android devices. It can give accurate layer thickness, density and roughness. The fitting has been performed using parratts formalism 4, and fitted parameters were the layer thicknesses t au and t fe 3 o 4 and the roughness of sample surface. Parrattbased and model independent xray reflectivity fitting procedure for nanoscale thin film characterization. Parratt implemented the complete field calculation for the prediction of the reflected part of the beam not only paving the way for xray reflectivity xrr analysis but also providing the basis for gixrf analysis.
Recent developments in the xray reflectivity analysis. In the conventional xrr analysis, the reflectivity is calculated based on the parratt formalism, accounting for the effect of. Xray reflectivity measurements are analyzed by fitting to the measured data a simulated curve calculated using the recursive parratts formalism combined with the rough interface formula. What is the best fitting software for xrr measurements. Xray reflectivity is a surfacesensitive analytical technique used in chemistry, physics, and. Genx is very modular and highly extensible and can be used. The fundamental framework for quantitative interpretation of xray reflectivity data was derived in the 1950s by parratt,19 though the task of carrying out the necessary recursion calculation by hand limited its application initially to simple systems. It is related to the complementary techniques of neutron reflectometry and ellipsometry. Advanced analysis techniques for xray reflectivities. Remagx is a scientific software to calculate and fit the specular xray reflection from a thin film sample taking into account magnetic contributions. Xray reflection at a multi layer mirror the bragg equation then changes to compensate for the refraction in the layers tho 2009.
A computer program for the inversion of xray reflectivities using the kinematical. Motofit download corefinement of multiple contrast neutron and xray reflectometry data, using the abeles matrix parratt recursion and least. Xray form factor, attenuation, and scattering tables nist. In the conventional xrr analysis, the xray reflectivity has been calculated based on the parratt formalism, accounting for the effect of roughness by the theory of nevotcroce conventionally. The software helps to significantly speed up the analysis by providing automatic fitting of simulated to experimental specular xray reflectivity curves. He also proposed a recursive method for the calculation in the presence of stratified media. Chapter 2 gives an introduction into the theory of xray reflectivity. The term both describes the physical phenomenon, as well as the experimental technique. Xray reflectivity can be employed to measure the thickness of films, e. Reflectivity refers to the measurement of the intensity of reflection off of a flat interface. It is used to determine layer thickness, density and roughness of thin layered samples. I have conducted the xray reflectivity experiments in situ and get more than 645 data.
Parrattbased and modelindependent xray reflectivity fitting. Parratts recursive formalism is the procedure used to calculate the xrr profile from. The key parameters in the equations are those that define the refractive index and linear absorption as a function of depth materials parameters, and those that define the incident beam characteristics instrumental parameters. Xray reflection analysis programs neutron and xray. Neutron and xray reflectivity analysis package igorprowavemetrics procedure. Realtime investigation of protein unfolding at an air. Reflectivity calculated using the fresnel equations for a semiinfinite medium. The reflectivity from a stack of different layers can be. Parratts initial work explored the surface of coppercoated glass, but since that time the technique has been. Density if a negative value is entered, the chemical formula is checked against a list of some common materials.
There are many available software packages which implement the parratt formalism. Parratt 105 developed a recursive formalism that provides equivalent results. Nrfit is designed as an accessible and handy neutron and xray reflectivity analysis package. Xray reflectivity and tem observation yoshikazu fujii kobe university, kobe 6578501, japan abstract surface and interface roughness of multilayer surface are often estimated with using xray reflectivity xrr. Nrfit uses the parratt formalism it is simple and easytouse and can provide a number of functions for roughness. Iucr realtime investigation of protein unfolding at an. Novel methods and universal software for hrxrd, xrr and. Xray reflectivity xrr is a powerfull tool for investigations on surface and interface structures of multilayered thin film materials. The fitting parameters are typically layer thicknesses, densities from which the index of refraction n \displaystyle n and eventually the wavevector z. Genx is a versatile program using the differential evolution algorithm for fitting xray and neutron reflectivity data. Corefinement of multiple contrast reflectometry data xray or neutron. However, to my knowledge this procedure gives a pretty good estimate on. The program is easily extensible, allowing users to incorporate their own models into the program. Parrattbased and modelindependent xray reflectivity fitting procedure for nanoscale thin film characterization.
Xray reflectvity measurements can be performed using a conventional power diffractometer 1. Ald and mbedeposited layers, in order to adjust growth rates. I hope to conduct the parratt fitting for these data and get the information about the thickness, roughness, and sld. The technique provides valuable information over a wide variety of scientific and technological applications including chemical aggregation, polymer and surfactant adsorption, structure of thin film magnetic. Xray reflectivity xrr is a technique for studying the detailed surface properties of materials. Interference patterns in specular reflection of xrays from thin films were described by. Genx is a versatile program using the differential evolution algorithm for fitting, primarily, xray and neutron reflectivity data, lately also surface xray diffraction data. Therefore it is usually hard to fit xray reflectivity with a chi2 criteria where we actually can calculate valid errorbars.
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