Oxygen analysis employing absorption spectroscopy
AssigneeAndors Analyzers Incorporated
InventorJacob Y. Wong
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Abstract
A method and apparatus are described for detecting the presence and amount of elemental oxygen in a sample cell. The intensity of extreme ultraviolet light passing through the sample cell at a wavelength band overlapping at least one of the Schumann-Runge absorption lines of oxygen is detected and compared with a predetermined non-absorbed condition of the ultraviolet light. The non-absorbed condition may be achieved by narrowing the wavelength band such that the band does not overlap the Schumann-Runge absorption line, or may be achieved by detecting the ultraviolet light passing through a reference cell. Also described is a novel ultraviolet source in which a cold zone captures neutral atoms of the emission gas to reduce the affect of resonance absorption of emitted ultraviolet light by such neutral atoms.
Claims9
A method for detecting the presence and amount of elemental oxygen in a sample cell, comprising, passing through the sample cell extreme ultraviolet light from a low pressure arc lamp emitting a wavelength band FWHM of less than about 0.50 angstrom unit, said band overlapping at least one of the Schumann-Runge absorption lines of oxygen at a substantial intensity, detecting the intensity of the ultraviolet light passing through the sample cell, comparing the detected intensity of the ultraviolet light with the intensity of a predetermined non-absorbed condition of said ultraviolet light, and producting a signal proportional to the difference in detected intensities to thereby represent oxygen concentration.
Apparatus for detecting the presence and amount of elemental oxygen, comprising, a sample cell for containing a gas to be analyzed, a low pressure arc lamp constituting a source of extreme ultraviolet light for passing through the sample cell extreme ultraviolet light at a wavelength band FWHM of less than about one angstrom unit, said band overlapping at least one of the Schumann-Runge absorption lines of oxygen at a substantial intensity, detector means for detecting the intensity of the ultraviolet light passing through said sample cell, means for comparing the detected intensity of the ultraviolet light with the intensity of a predetermined non-absorbed condition of said ultraviolet light, and producing a signal proportional to the difference in detected intensities to thereby represent oxygen concentration.
Dependencies are inferred from the claim text.