CrossRoads Scientific

In addition to the complete integrated package, the individual libraries can be licensed, as well as custom packages that include a version that can be called from remote host programs using Active-X communications. In this configuration the user interface can be maintained or a host GUI substituted and XRS-FP used as an “engine” to do XRF analysis that is both file and command driven. The individual libraries can be interfaced to either VC++ or VB host programs for custom applications. Please contact CrossRoads Scientific for details regarding your own specific requirements.

In addition to the basic FP (Fundamental Parameter) method for quantitative analysis using x-ray physics equations, there are several options available including the use of the Compton scatter peak for calculations for either light-element estimation. In addition, simple least-squares empirical calibrations may be performed using peak intensities or the ratios of intensities to either the Compton or Rayleigh scatter peaks, or the local background under the peaks.

The standard package can analyze either bulk materials or a single-layer thin-film material. An optional package (XRS-MTFFP) can analyze multilayers for both thickness and composition within stacks up to eight layers thick. Thin-film analysis requires some kind of calibration with standards, but bulk FP analysis can be performed without any calibration at all.

Elements/Components

Up to 40 elements (could be configured for up 100) can be analyzed, as individual elements and/or compounds. Unanalyzed elements can be specified stoichiometrically bound with an analyzed element (e.g., oxides or carbonates). Elements can be analyzed in one or more compounds within the same analysis. One compound (or element) can be analyzed by difference. Any number of compounds (or elements) can be “fixed.” E.g., solutions, binders and/or hydrated crystals can be analyzed this way.

General Bulk and Thin-Film Analysis

Any bulk, or single-layer (unsupported) thin-film, sample can be analyzed by either standardless or a calibration-with-standards FP approach. The program can use up to 6 excitation conditions per analysis. Each excitation condition can vary almost any analysis setup, including the kV, acquire time, tube (or secondary) target, detector type, detector or tube filter, source focusing optic, atmosphere (air, vacuum, helium), and spectrum processing (e.g., deconvolution type, background, sum & escape peak removal).

Analysis with or without Standards

Many detectors and windows can be fully modeled. This allows analysis without any standards, with normalization to 100% (or any specified factor). This is only possible when a single excitation condition is used. When more than one excitation is used, at least one of the elements for each condition must have been calibrated. Calibration factors may be generated using any type of standard (e.g., pure element or analytical “type” standard). A single “type” standard may be used, or the calibration may be done with a different standard for each element, or any combination of standards may be used. If some elements are calibrated, and some are not, the missing calibration coefficients are derived from the existing ones. The mass thickness of the sample can either be specified or calculated. In the latter case the analysis cannot be done without standards. Several units are possible for thickness measurement, and the density can be calculated theoretically or specified, in the case of linear thickness calculations. Composition units may be ppm or wt%, with the additional output of atomic and mole percent. An optional calibration option, MLSQ, can be used to create FP calibrations from multiple type standards.

Excitation Sources

Different x-ray tube types (“reflection” or transmission) can be modeled, using two analytical models (Pella or Ebel), or by the use of a supplied source spectrum, for complete polychromatic source modeling. Different tube windows and filters may also be included. The tube window can be of any composition (e.g., BeO or glass). Any tube anode element may be specified, as well as the tube (electron) incidence and take-off angles. The kV may range from 3 to 60 kV. Provision is provided for including a transmission efficiency file for use with, for example, polycapillary optics placed between the source and the sample. Radioisotopes can be used, using a source file describing the relative line ratios. For secondary target excitation, monochromatic excitation is assumed. Several layers of filters can also be included in the source model.

Detectors

Various detectors (e.g., Si{Li}, CdTe, Si pin-diode, Si drift detector) and windows can be fully modeled. The software has provision for the user to input all the required parameters (e.g., contact material and thickness, dead layer, etc.) associated with these detectors (and their windows).

Geometry

The complete system geometry can be specified, including the sample incidence and take-off angles, the source-to-optic and/or source-to-sample distances, the sample-to-detector distance, as well as the environmental factors (see above).

Elements, Lines and Interelement corrections

The FP calculations include full corrections for absorption and both thick and thin-film secondary fluorescence. All possible lines are considered for both excitation and fluorescence. The analysis can be performed for all elements from H through Fm, using K, L or M lines in the energy range from 0.05 keV up to 120 keV.

MLSQ


This option allows FP calibrations to use multiple standards and various additional regression models used to refine the FP calibration coefficients.  It can also perform a simple XRF regression calibrations, without FP, using concentrations vs. intensities, or intensity ratios (peak/Compton, peak/background, etc.).

Statistics



Automatic Peak/Element ID


This optional module automatically analyzes a spectrum and assigns the most-likely elements and lines to each identified peak, and assembles a complete list of likely elements in the spectrum.  This list can be added to the main analysis panel (see above) for further spectral or quantitative analysis.

Spectrum Calibration

Using two known peaks in the spectrum, the software can calculate the effective gain (eV/channel) and offset (zero shift) for the spectrometer. These factors can then routinely be applied to subsequent spectra prior to other spectrum processing. It is vital that peaks are located at their expected energies, otherwise the spectrum processing cannot function correctly.

Background Removal


The automatic background module uses iterative filtering to remove all peaks, leaving behind the spectral background. The background spectrum is displayed and removed from the original spectrum. Optionally a background spectrum file may be used to model the background in the analyzed spectrum.

Escape Peak and Sum Peak Removal

Routines are available to optionally correct for both detector escape and sum (pile-up) peaks.  Supported detectors include Si(Li), Si-pin, Si-drift, CdTe and Proportional Counters.  The subtracted escape and sum events are added back to the spectrum in their parent peak locations.  The escape or sum peak spectrum is also displayed for reference.

Smoothing

A specified number of 1:2:1 Gaussian smooths, or other filters (such as Savitsky-Golay), can be applied to a spectrum.  The resulting spectrum is compared with the original spectrum.

Intensity Extraction

Specified element peaks may be integrated over a fixed ROI (Region Of Interest), or the complete spectrum can be fit using either synthetic Gaussians for every possible line in the regions of interest, or reference profiles that are acquired experimentally. One of six major lines (Kα, Kβ, Lα, Lβ, Lγ, Mα) is selectable as the main analysis peak for intensity extraction. All relevant lines, required for deconvolution, are then automatically included by the software for full overlap correction using a leastsquares fitting procedure.

All required line energies and resolutions are calculated automatically from the specified analyte line. The Gaussian peak fitting can be done with a linear or non-linear least-squares approach. The latter allows constrained changes in the peak positions, intra-series line ratios, and peak widths, from their nominal starting points. The Reference deconvolution method (separate library) is more restricted and is typically used without any adjustments of line ratios and peak positions.


An option is available to include the Compton and Rayleigh scatter peaks in the spectrum peak fitting.  This accomodates both peak overlap issues and also allows the calculation of peak intensity to scatter ratios for least-squares calibrations that do not require the FP model.

In addition to calculating elemental intensities, the software automatically calculates the estimated uncertainty and background values, which allows uncertainty and Minimum Detection Limit (MDL) calculations to be performed during the FP analysis.

Annotation

The spectrum display panel can be annotated and exported in many different formats for embedding in other programs and reports.  Below is an example of the panel with annotations showing some of the features of the spectrum display.



Spectrum Acquisition

Optional modules are available for acquiring a spectrum directly into the XRS-FP software. These options include the use of the Amptek MCA-8000A and DP4/PX4 spectrum acquisition hardware and drivers. Other options are also available.

Tube Control

It is possible to supply software to control a High-Voltage Power Supply (HVPS) and monitor the output
of an x-ray tube. Consult CrossRoads Scientific for more details.


For more details consult the Software User's Guide - XRS-FP Software Guide v460.pdf