Angle calibration for grazing-incidence X-ray fluorescence (GIXRF)
A method includes directing an X-ray beam to be incident at a grazing angle on a location on a surface of the sample. An X-ray fluorescence excited at the location is measured. A reflection angle of the X-ray beam from the surface and a transmission angle of the X-ray beam are measured. An angle of incidence of the X-ray beam on the surface is evaluated using the measured reflection and transmission angles, and the measured X-ray fluorescence is analyzed using the evaluated angle of incidence.
1. A method for analysis of a sample, comprising:
directing an X-ray beam to be incident at a grazing angle on a location on a surface of the sample;
measuring X-ray fluorescence excited at the location;
measuring a reflection angle of the X-ray beam from the surface and a transmission angle of the X-ray beam;
evaluating an angle of incidence of the X-ray beam on the surface using the measured reflection and transmission angles; and
analyzing the measured X-ray fluorescence using the evaluated angle of incidence.
2. The method according to claim 1 , wherein directing the X-ray beam comprises focusing the X-ray beam so as to converge on the surface of the sample.
3. The method according to claim 1 , wherein measuring the transmission angle comprises assessing the transmission angle while the sample is not present.
4. The method according to claim 1 , wherein measuring the transmission angle comprises assessing the transmission angle of the X-ray beam through the sample.
5. The method according to claim 1 , wherein measuring the reflection and transmission angles comprises positioning an array detector perpendicular to the surface of the sample, and configuring the array detector to sense a reflection of the X-ray beam from the surface and to sense a transmission of the X-ray beam.
6. The method according to claim 1 , wherein evaluating the angle of incidence comprises averaging the measured reflection and transmission angles to determine an angular deviation of the surface relative to a mean plane thereof.
7. The method according to claim 6 , wherein evaluating the angle of incidence comprises calculating an actual angle of incidence by summing the angular deviation of the surface and a nominal incident angle to the surface.
8. The method according to claim 7 , wherein analyzing the measured X-ray fluorescence comprises finding a corrected intensity of the X-ray fluorescence in terms of the measured X-ray fluorescence, the actual angle of incidence and the nominal incident angle.
9. The method according to claim 1 , wherein measuring and analyzing the X-ray fluorescence are performed using the X-ray beam used for evaluating the angle of incidence.
10. The method according to claim 1 , wherein measuring and analyzing the X-ray fluorescence are performed using a second X-ray beam, which has a known angular offset relative to the X-ray beam used for evaluating the angle of incidence.
11. Apparatus, comprising:
an X-ray source, which is configured to generate and direct an X-ray beam to be incident at a grazing angle on a location on a surface of a sample;
a first detector, which is configured to measure X-ray fluorescence excited at the location by the X-ray beam;
a second detector, which is configured to sense a reflection of the X-ray beam from the surface and a transmission of the X-ray beam; and
a processor, which is configured to measure a reflection angle of the reflection and a transmission angle of the transmission, to evaluate an angle of incidence of the X-ray beam on the surface using the measured reflection and transmission angles, and to analyze the measured X-ray fluorescence using the evaluated angle of incidence.
12. The apparatus according to claim 11 , wherein the X-ray source is configured to focus the X-ray beam so as to converge on the surface of the sample.
13. The apparatus according to claim 11 , wherein the second detector is configured to sense the transmission of the X-ray beam while the sample is not present.
14. The apparatus according to claim 11 , wherein the second detector is configured to sense the transmission of the X-ray beam through the sample.
15. The apparatus according to claim 11 , wherein the second detector comprises an array detector positioned perpendicularly to the surface of the sample, and configured to sense the reflection of the X-ray beam from the surface and the transmission of the X-ray beam.
16. The apparatus according to claim 11 , wherein the processor is configured to average the measured reflection and transmission angles so as to determine an angular deviation of the surface relative to a mean plane thereof.
17. The apparatus according to claim 16 , wherein the processor is configured to calculate an actual angle of incidence by summing the angular deviation of the surface and a nominal incident angle to the surface.
18. The apparatus according to claim 17 , wherein the processor is configured to find a corrected intensity of the X-ray fluorescence in terms of the measured X-ray fluorescence, the actual angle of incidence and the nominal incident angle.
19. The apparatus according to claim 11 , wherein the first detector is configured to measure the X-ray fluorescence and the processor is configured to analyze the X-ray fluorescence using the X-ray beam used for evaluating the angle of incidence.
20. The apparatus according to claim 11 , wherein the X-ray source is further configured to generate and direct a second X-ray beam, which has a known angular offset relative to the X-ray beam used for evaluating the angle of incidence, and wherein the first detector is configured to measure the X-ray fluorescence and the processor is configured to analyze the X-ray fluorescence using the second X-ray beam.