Patent Number: 
Section: claims

1. A multilayer structure for reflecting x-rays comprising:a substrate having formed on a surface thereof at least one period of individual layers, wherein the at least one period includes at least three individual layers including a first layer, a second layer, and a third layer, wherein the first layer includes magnesium silicide (Mg2Si), the second layer includes at least one of silicon (Si), carbon (C), silicon carbide (SiC), boron (B), and boron carbide (B4C), and the third layer includes at least one of tungsten (W), tantalum (Ta), cobalt (Co), nickel (Ni), copper (Cu), iron (Fe), chromium (Cr), and alloys, oxides, borides, silicides, and nitrides of these elements. 2. The multilayer structure of claim 1 wherein the second layer is disposed between the first layer and the third layer, wherein the second layer includes silicon carbide (SiC) and the third layer includes tungsten (W). 3. The multilayer structure of claim 1 wherein the at least one period includes a fourth layer, wherein the fourth layer includes at least one of silicon (Si), carbon (C), silicon carbide (SiC), boron (B), and boron carbide (B4C), wherein the second layer is disposed between the first layer and the third layer, wherein the third layer is disposed between the second layer and the fourth layer. 4. The multilayer structure of claim 1 wherein the individual layers within the at least one period have the same thickness. 5. The multilayer structure of claim 1 wherein the individual layers within the at least one period have different thicknesses. 6. The multilayer structure of claim 1 wherein the structure includes at least 10 of the periods. 7. The multilayer structure of claim 1 wherein the structure includes at least 50 of the periods. 8. The multilayer structure of claim 1 wherein the at least one period is between 1 and 60 nanometers in thickness. 9. The multilayer structure of claim 1 wherein the at least one period is between 1.5 and 10 nanometers in thickness. 10. The multilayer structure of claim 1 wherein the first layer of the at least one period is configured to be exposed to x-ray radiation before the second and third layers of the same period. 11. The multilayer structure of claim 1 wherein the at least one period includes a top period configured to be exposed to x-ray radiation before any other period, wherein the top period includes a cap layer, the cap layer configured to be exposed to radiation before any other layer, wherein the cap layer includes one of silicon (Si), silicon carbide (SiC), silicon oxide (SiO2), and any other antireflective oxide. 12. The multilayer structure of claim 11 wherein the cap layer includes more than one layer of materials. 13. An x-ray fluorescence spectroscopy system comprising:an x-ray source emitting an x-ray radiation field on a sample; anda multilayer structure including a substrate having formed on a surface thereof at least one period of individual layers, wherein the at least one period includes at least three individual layers including a first layer, a second layer, and a third layer, wherein the first layer includes magnesium silicide (Mg2Si), the second layer includes at least one of silicon (Si), carbon (C), silicon carbide (SiC), boron (B), and boron carbide (B4C), and the third layer includes at least one of tungsten (W), tantalum (Ta), cobalt (Co), nickel (Ni), copper (Cu), iron (Fe), chromium (Cr), and alloys, oxides, borides, silicides, and nitrides of these elements, wherein the sample emits a fluorescent radiation field in response to the x-ray radiation field, and wherein the multilayer structure selectively reflects the fluorescent radiation field. 14. The system of claim 13 wherein the first layer of the at least one period is exposed to the radiation before the second and third layers of the same period. 15. The system of claim 13 wherein the at least one period includes a fourth layer, wherein the fourth layer includes at least one of silicon (Si), carbon (C), silicon carbide (SiC), boron (B), and boron carbide (B4C), wherein the second layer is disposed between the first layer and the third layer, wherein the third layer is disposed between the second layer and the fourth layer. 16. The system of claim 13 wherein the at least one period includes a top period exposed to the radiation before any other period, wherein the top period includes a cap layer, the cap layer exposed to the radiation before any other layer, wherein the cap layer includes one of silicon (Si), silicon carbide (SiC), silicon oxide (SiO2), and any other antireflective oxide. 17. The system of claim 16 wherein the cap layer includes more than one layer of materials. 18. The system of claim 13 wherein the individual layers within the at least one period have the same thickness. 19. The system of claim 13 wherein the individual layers within the at least one period have different thicknesses. 20. The system of claim 13 wherein the multilayer structure includes at least 10 of the periods. 21. The system of claim 13 wherein the multilayer structure includes at least 50 of the periods. 22. The system of claim 13 wherein the at least one period is between 1 and 60 nanometers in thickness. 23. The system of claim 13 wherein the at least one period is between 1.5 and 10 nanometers in thickness. 24. The system of claim 13 wherein the second layer is disposed between the first layer and the third layer, wherein the second layer includes silicon carbide (SiC) and the third layer includes tungsten (W). 25. A method of x-ray fluorescence spectroscopy comprising:providing a field of x-ray radiation;irradiating a sample to be analyzed with the field of x-ray radiation, thereby inducing a field of fluorescence radiation;directing the field of fluorescence radiation from a multilayer reflector including a substrate having formed on a surface thereof at least one period of individual layers, wherein the at least one period includes at least three individual layers including a first layer, a second layer, and a third layer, wherein the first layer includes magnesium silicide (Mg2Si), the second layer includes at least one of silicon (Si), carbon (C), silicon carbide (SiC), boron (B), and boron carbide (B4C), and the third layer includes at least one of tungsten (W), tantalum (Ta), cobalt (Co), nickel (Ni), copper (Cu), iron (Fe), chromium (Cr), and alloys, oxides, borides, silicides, and nitrides of these elements; andanalyzing the field of fluorescence radiation emitted by the sample. 26. The method of claim 25 wherein the second layer is disposed between the first layer and the third layer, wherein the second layer includes silicon carbide (SiC) and the third layer includes tungsten (W).