Instrument and method for x-ray diffraction, fluorescence, and crystal texture analysis without sample preparation

Abstract

An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation of, and claims benefit of priority to, U.S. patent application Ser. No. 11 / 706,693 filed Feb. 14, 2007, entitled “Instrument And Method For X-ray Diffraction, Fluorescence, And Crystal Texture Analysis Without Sample Preparation”, and U.S. Provisional Patent Application No. 60 / 773,244 filed on Feb. 14, 2006, entitled “Instrument And Method For X-ray Diffraction, Fluorescence, And Crystal Texture Analysis Without Sample Preparation” and U.S. Provisional Application No. 60 / 776,576 filed on Feb. 24, 2006, entitled “Instrument And Method For X-ray Diffraction, Fluorescence, And Crystal Texture Analysis Without Sample Preparation” all of which is hereby incorporated by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]The described herein was made in the performance of work under a NASA contract or grant and by employees of the United States Government and is subjec...

AI Technical Summary

Benefits of technology

[0013]In some aspects of the present concepts, an XRD / XRF instrument and method are provided which are particularly suited for extraterrestrial applications, such as may be used in combination with a rover, landing vehicle, or craft. Such a flight-instrument application requires that the instrument be robust, lightweight, and low in power consumption. In addition, risk must be minimized whenever possible. The XRD / XRF instrument presently disclosed herein, relative to conventional XRD / XRF instruments, eliminates moving parts, eliminates sample preparation needs, provides an efficient geometry, provides improved sensitivity, and eliminates the need to place samples in vacuum, each of which improvements decrease risk and, in combination, significantly decreases risks. Further, the XRD / XRF instrument and method provided herein should provide a platform for compact and rugged packaging that consumes a minimal amount of power. It is believed that a commercial XRD / XRF instrument based on the presently disclosed instrument and methods would cost significantly less than conventional XRD / XRF instruments.

[0014]In accord with disclosed aspects of the present concepts, an instrument and method for X-ray diffraction using a reflection geometry (and the methodology presented here; e.g. continuum X-ray source, and photon counting imaging spectrometer detectors) permit measuring the atomic plane spacings of unprepared material samples. The method described herein may alternatively be implemented in a transmission geometry. Further to providing material identification, the instrument(s) and method(s) permit the determination of the crystalline grain size, domain size, and orientation distributions (i.e., crystalline texture) within samples, which provide important information on crystallographic structure, material defects, and stresses or shocks that the sample may have experienced. The new method(s) described herein are very efficient compared to standard XRD techniques (including CheMin) for mineral and chemical identification. Further, the disclosed simultaneous X-ray fluorescence analysis capability provides elemental abundances.

Problems solved by technology

However, in certain applications, such as extraterrestrial XRD analysis, the number of moving parts required increases (e.g., the CheMin device uses a carousel disc and associated drive system, sample preparation systems such as a fine-grinding mill, etc.), with corresponding increases in power consumption, mass, and risk.

For the CheMin XRD / XRF apparatus 32, which is presently slated for inclusion on the Mars Science Laboratory (MSL) mission scheduled for launch in 2009, sample preparation is required, which would disadvantageously destroy any water ice that MSL may encounter and cause it to evaporate in the low pressure environment on Mars.

Sample preparation also destroys valuable scientific and engineering information regarding grain size and orientation distributions and evidence of stresses and shock.

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