Method of measurement of the concentration of a substance contained in a gas and devices for carrying out said method
AssigneeAgence Nationale de Valorisation de la Recherche (ANVAR)
InventorsJean-Loup Bertaux, Jacques Alain Quessette
Life of this patent
Estimating the term…
Abstract
In a method for measuring the concentration of a substance contained in a gas, the gas is irradiated with a radiation having a sufficiently short wavelength to photodissociate the substance. A photometric measurement is then carried out on at least one of the products of photodissociation in order to determine its concentration which is proportional to the concentration of the substance to be measured.
Claims19
A method of measurement of the concentration of a photodissociable substance contained in a gas, wherein:
- a gas having an unknown content of photodissociable substance is irradiated with a radiation having a sufficiently short wavelength to photodissociate said substance,
- a photometric measurement is carried out on at least one of the photodissociation products in order to determine its concentration under conditions under which the concentration of the photodissociation product is proportional to the concentration of the substance to be measured.
A method of measurement of the concentration of water vapor contained in a gas, wherein:
- said gas is irradiated with a radiation having a sufficiently short wavelength shorter than 1360 A to dissociate the water vapor into dissociation products consisting of the hydrogen atom H and the OH radical, the latter being accordingly produced at the time of photodissociation in an excited OH* state, and
- photometric measurement is carried out which consists in measuring the intensity of the radiation emitted within the range of 3000 to 3250 A at the time of de-excitation of the OH* radical.
A method of measurement of the concentration of a substance contained in a gas, wherein:
- a gas having an unknown content of a photodissociable substance is irradiated with a radiation having a sufficiently short wavelength to photodissociate said substance,
- a photometric measurement is carried out in two different zones of the gas on at least one of the photodissociation products in order to determine its concentration under conditions under which the concentration of the photodissociation product is proportional to the concentration of the substance to be measured, and
- a comparison of the results obtained in respect of the two zones is performed to determine the concentration of said substance.
A device for measuring the concentration of a photodissociable substance contained in a gas, which device comprises:
- a source of radiation which emits a radiation having a wavelength shorter than 1360 A disposed for irradiating a volume of said gas, and
- photometric measuring means constituted by at least one photodetector having a range of sensitivity which includes the waveband from 3000 A to 3250 A, disposed for detecting emission of said radiation in said gas.
A device for measuring the concentration of a photodissociable substance in a gas, which device comprises:
- a first source of radiation having a wavelength shorter than 1360 A for irradiating the gas, and
- photometric measuring means constituted by a second radiation source in which the spectrum contains the wavelength of 1216 A and by a photodetector which is sensitive at 1216 A.
A method of measuring the concentration of contaminants in the atmosphere, wherein:
- a volume of atmospheric air is irradiated with a radiation having a sufficient short wavelength to photodissociate contaminants,
- a photometric measurement is carried out in two different zones of the irradiated air on at least one of the photodissociation products in order to determine its concentration under conditions under which the concentration of the photodissociation product is proportional to the concentration of a contaminant of which it is a photodissociation product, and
- a comparison of the results obtained in respect of the two zones is performed to determine the concentration of said contaminant.
Dependencies are inferred from the claim text.