Measuring the concentration of gaseous hydrogen fluoride
First Claim
1. A method for quantitatively determining the concentration of gaseous hydrogen fluoride in a medium containing gaseous hydrogen fluoride, characterised in that said method comprises combining the results of (a) a measurement of the transmission or absorption of a laser beam at a first frequency corresponding to a neon 3 p4 -2 s2 transition through said medium containing gaseous hydrogen fluoride, and (b) a measurement of the transmission or absorption of a laser beam at a second frequency excluding said first frequency, through said medium containing gaseous hydrogen fluoride.
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Abstract
Method and apparatus for quantitatively determining the concentration of gaseous hydrogen fluoride in a medium containing gaseous hydrogen fluoride. The apparatus has one or two lasers (1) (2) which provides a beam (11) having two frequencies, a first frequency which is absorbed by gaseous hydrogen fluoride and a second frequency which is substantially unabsorbed by low pressure gaseous hydrogen fluoride and less absorbed than the first frequency by high pressure gaseous hyrogen fluoride or gaseous hydrogen fluoride plus other gases or vapors. Detectors (12) (15) detect the beam transmitted through the medium and calculator (18) determines the concentration from the outputs of the detectors (12) (15). The preferred lasers (1) (2) are infra red helium-neon lasers.
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Citations
13 Claims
- 1. A method for quantitatively determining the concentration of gaseous hydrogen fluoride in a medium containing gaseous hydrogen fluoride, characterised in that said method comprises combining the results of (a) a measurement of the transmission or absorption of a laser beam at a first frequency corresponding to a neon 3 p4 -2 s2 transition through said medium containing gaseous hydrogen fluoride, and (b) a measurement of the transmission or absorption of a laser beam at a second frequency excluding said first frequency, through said medium containing gaseous hydrogen fluoride.
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6. An apparatus for quantitatively determining the concentration of gaseous hydrogen fluoride in a medium containing gaseous hydrogen fluoride, characterised in that said apparatus comprises:
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(i) a first source of laser light at a first frequency corresponding to a neon 3 p4 -2 s2 transition; (ii) first detecting means associated with said first source, located remote from said first source by a suitable path length for detecting the intensity or absorption of said laser light at said first frequency; (iii) a second source of laser light at a second frequency excluding said first frequency; (iv) second detecting means associated wth said second source, located remote from said second source by a suitable path length for detecting the intensity or absorption of said laser light at said second frequency; and (v) calculating means associated with the outputs of said first and second detecting means to calculate said concentration; and wherein said medium containing gaseous hydrogen fluoride is located between said first and second sources and said first and second detecting means so that laser light from said first and second sources passes through said medium containing gaseous hydrogen fluoride to said first and second detecting means. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification