Filter for X-ray radiation, and an arrangement for using filtered X-ray radiation for excitation
An X-ray fluorescence measurement device comprises an X-ray source and a sample window for allowing X-rays from the X-ray source reach a sample. A filter arrangement between the X-ray source and the sample window includes a first filter layer comprising a first filtering element and a second filter layer including a second filtering element. The atomic number of the second filtering element is greater than the atomic number of the first filtering element. The first filter layer is between the X-ray source and the second filter layer.
1. A filter arrangement for X-ray radiation, comprising:
a first filter layer comprising a first filtering element, which has an atomic number, and
a second filter layer comprising a second filtering element, which has an atomic number that is greater than the atomic number of the first filtering element;
wherein said first filter layer and said second filter layer are adapted to be supported between an X-ray source and a sample to be subjected to X-ray fluorescence analysis, and said first filter layer is adapted to be supported between said X-ray source and said second filter layer, and wherein said second filtering element is one of the group consisting of rhodium and palladium.
2. A filter arrangement according to claim 1 , wherein said first filtering element is nickel.
3. A filter arrangement according to claim 2 , wherein the first filter layer is a sheet of nickel having a thickness of essentially 20 micrometers, and the second filter layer is a sheet of rhodium or palladium having a thickness of essentially 3.5 micrometers.
4. A filter arrangement according to claim 1 , wherein said first filtering element is copper.
5. A filter arrangement according to claim 4 , wherein the first filter layer is a sheet of copper having a thickness of essentially 20 micrometers, and the second filter layer is a sheet of rhodium or palladium having a thickness of essentially 3.5 micrometers.
6. A filter arrangement according to claim 1 , wherein the first and second filter layers are attached to each other to constitute a single mechanical entity.
7. A filter arrangement according to claim 1 , comprising a support layer made of material essentially transparent to X-rays and adapted to mechanically support at least one of said first filter layer and said second filter layer.
8. An X-ray fluorescence measurement device, comprising:
an X-ray source,
a sample window for allowing X-rays from said X-ray source reach a sample to be subjected to X-ray fluorescence analysis, and
a filter arrangement between said X-ray source and said sample window;
wherein said filter arrangement comprises a first filter layer comprising a first filtering element, which has an atomic number, and a second filter layer comprising a second filtering element, which has an atomic number that is greater than the atomic number of the first filtering element, and said first filter layer is between said X-ray source and said second filter layer, and said second filtering element is one of the group consisting of rhodium and palladium.
9. An X-ray fluorescence measurement device according to claim 8 , wherein:
said X-ray source is an X-ray tube that has an anode, which comprises tungsten as anode material , and
said first filtering element is nickel.
10. An X-ray fluorescence measurement device according to claim 9 , wherein the first filter layer is a sheet of nickel having a thickness of essentially 20 micrometers, and the second filter layer is a sheet of rhodium or palladium having a thickness of essentially 5micrometers.
11. An X-ray fluorescence measurement device according to claim 8 , wherein:
said X-ray source is an X-ray tube that has an anode, which comprises at least one of rhenium, platinum or gold as anode material, and
said first filtering element is copper.
12. An X-ray fluorescence measurement device according to claim 11 , wherein the first filter layer is a sheet of copper having a thickness of essentially 20 micrometers, and the second filter layer is a sheet of rhodium or palladium having a thickness of essentially 5 micrometers.
13. An X-ray fluorescence measurement device according to claim 8 , comprising a filter changer adapted to controllably move at least one filter layer of said filter arrangement into and out of the path between said X-ray source and said sample window.
14. An X-ray fluorescence measurement device according to claim 8 , comprising a third filter layer between said first filter layer and said sample window, said third filter layer comprising a third filtering element, which has an atomic number that is smaller than the atomic numbers of the first and second filtering elements.
15. An X-ray fluorescence measurement device according to claim 14 , wherein said third filtering layer is a sheet of aluminum having a thickness of essentially 200 micrometers.