Detecting minority gaseous species by light-emission spectroscopy
First Claim
1. A method of using light-emission spectroscopy to detect at least one gaseous species that is in a minority and/or difficult to excite in a mixture with at least one gaseous species that is in a majority and/or more easily excitable, in which a plasma is used in the gas mixture for analysis, and an original optical spectrum of the radiation emitted by the plasma is measured for subsequent comparison between the emitted spectrum and a library of known spectra, the method comprising a detection step that makes use, in the original spectrum, of one or more lines that are characteristic of the gaseous species in a majority and/or that is easily excitable, said line(s) being of amplitude that is sensitive to the presence of the species that is in a minority and/or that is difficult to excite, and information is deduced from the amplitude of said line(s) concerning the concentration of the gaseous species that is in a minority and/or that is difficult to excite, wherein said method further comprising displaying said information.
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Abstract
A method and apparatus for detecting minority gaseous species in a mixture by light-emission spectroscopy by means of an optical spectrometer (8), in which the radiation emitted by a plasma (4) present in the gas mixture for analysis is used and, in the spectrum of the radiation, lines are identified of a majority gaseous species that present amplitudes that are sensitive to the presence of a minority species, and information about the concentration of a minority gaseous species is deduced from the amplitude(s) of the sensitive line(s). This makes it possible to monitor minority gaseous species in real time.
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Citations
21 Claims
- 1. A method of using light-emission spectroscopy to detect at least one gaseous species that is in a minority and/or difficult to excite in a mixture with at least one gaseous species that is in a majority and/or more easily excitable, in which a plasma is used in the gas mixture for analysis, and an original optical spectrum of the radiation emitted by the plasma is measured for subsequent comparison between the emitted spectrum and a library of known spectra, the method comprising a detection step that makes use, in the original spectrum, of one or more lines that are characteristic of the gaseous species in a majority and/or that is easily excitable, said line(s) being of amplitude that is sensitive to the presence of the species that is in a minority and/or that is difficult to excite, and information is deduced from the amplitude of said line(s) concerning the concentration of the gaseous species that is in a minority and/or that is difficult to excite, wherein said method further comprising displaying said information.
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