US3703726A
Expired / Lapsed
US
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Quantitative chemical analysis by x-ray emission spectroscopy
Assignee: Corning Glass Works
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Filing: 1970-12-31
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Granted: 1972-11-21
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Expires: 1990-12-31
Abstract
Abstract In X-ray emission spectrometry a quantitative chemical analysis of the elements in an unknown sample is obtained. A standard, or standards, whose composition has previously been accurately established is used to determine the first order approximation to the original intensity of the most efficient excitation energy for each element being determined. The most efficient excitation energy is defined as that energy which is just greater than the energy of the absorption edge of the characteristic X-ray emission line employed in the analysis. Using the computed original intensity of the most efficient excitation energy for each element in the standard(s), the observed X-ray intensities measured on the unknown, and an assumed chemical composition of the unknown, the expected characteristic X-ray intensity for each element in the unknown is computed. The assumed chemical composition of the unknown is then adjusted by a self-consistent iterative procedure until the expected and observed X-ray intensities for each element being determined agree. In this manner the best estimate of the chemical composition of the unknown is determined.
Inventors
- 👤 Donald A Stephenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:21
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/22; G01N23/223; G01N2223/00; G01N2223/07; G01N2223/076
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
144 words
In X-ray emission spectroscopy a method of quantitative chemical analysis of an unknown sample, wherein each of the following computing steps iS performed on automatic computing apparatus, said method comprising: a. irradiating a known standard with X-rays to produce an observed characteristic X-ray intensity from the elements in the standard, b. computing from the observed X-ray intensity of the elements in the standard the first order approximation of the intensity of the most efficient excitation energy for each element, c. computing from said approximations of the intensity of the most efficient excitation energy and an assumed chemical composition of said unknown sample, the expected characteristic X-ray intensity of elements in said sample, and d. adjusting the assumed chemical composition of the unknown sample used in step (c) until said expected X-ray intensities match the observed X-ray intensities of each element in said unknown sample.
Claim 2
Dependent Claim
144 words
In X-ray emission spectroscopy a method of quantitative chemical analysis of an unknown sample, wherein each of the following computing steps iS performed on automatic computing apparatus, said method comprising: a. irradiating a known standard with X-rays to produce an observed characteristic X-ray intensity from the elements in the standard, b. computing from the observed X-ray intensity of the elements in the standard the first order approximation of the intensity of the most efficient excitation energy for each element, c. computing from said approximations of the intensity of the most efficient excitation energy and an assumed chemical composition of said unknown sample, the expected characteristic X-ray intensity of elements in said sample, and d. adjusting the assumed chemical composition of the unknown sample used in step (c) until said expected X-ray intensities match the observed X-ray intensities of each element in said unknown sample.
Claim 3
Dependent Claim
144 words
In X-ray emission spectroscopy a method of quantitative chemical analysis of an unknown sample, wherein each of the following computing steps iS performed on automatic computing apparatus, said method comprising: a. irradiating a known standard with X-rays to produce an observed characteristic X-ray intensity from the elements in the standard, b. computing from the observed X-ray intensity of the elements in the standard the first order approximation of the intensity of the most efficient excitation energy for each element, c. computing from said approximations of the intensity of the most efficient excitation energy and an assumed chemical composition of said unknown sample, the expected characteristic X-ray intensity of elements in said sample, and d. adjusting the assumed chemical composition of the unknown sample used in step (c) until said expected X-ray intensities match the observed X-ray intensities of each element in said unknown sample.
Claim 4
Dependent Claim
144 words
In X-ray emission spectroscopy a method of quantitative chemical analysis of an unknown sample, wherein each of the following computing steps iS performed on automatic computing apparatus, said method comprising: a. irradiating a known standard with X-rays to produce an observed characteristic X-ray intensity from the elements in the standard, b. computing from the observed X-ray intensity of the elements in the standard the first order approximation of the intensity of the most efficient excitation energy for each element, c. computing from said approximations of the intensity of the most efficient excitation energy and an assumed chemical composition of said unknown sample, the expected characteristic X-ray intensity of elements in said sample, and d. adjusting the assumed chemical composition of the unknown sample used in step (c) until said expected X-ray intensities match the observed X-ray intensities of each element in said unknown sample.
Claim 5
Dependent Claim
173 words
The method recited in claim 1 wherein the step of computing the first order approximation of the original intensity of the most efficient excitation energy of each element is performed in accordance with: where Ii* is the first order approximation of the intensity of the most efficient excitation energy of the ith element, Ii is the observed X-ray intensity for the ith element, theta 1 is the angle of incidence of the irradiating energy, theta 2 is the angle at which characteristic X-rays are observed, Mu sp is the mass absorption coefficient of the sample for the most efficient X-rays, Mu si is the mass absorption coefficient of the sample for the ith radiation, Mu ip is the mass absorption coefficient of the ith element for the most efficient X-rays, Wi is the weight fraction of element i, Ki is the absorption edge jump ratio for the ith element, Omega i is the fluorescent yield of the ith element, and Ri is the fraction of the characteristic X-rays in the analyzed line''s series.
References Cited (Backward Citations)
US3456108A
Cited
US3428802A
Cited
US3537820A
Cited
US3553444A
Cited
US3581087A
Cited
US3600567A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-21 | 1976-05-22 | 1976-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-21 | 1980-05-22 | 1980-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-21 | 1984-05-22 | 1984-11-21 | $7700.00 | Window Closed / Lapsed |