Abstract: A gas concentration measuring apparatus utilizing a gas correlation method capable of measuring concentrations of a plurality of analyte gases simultaneously and at high sensitivity uses an infrared light source (2) such as an infrared semiconductor diode or a quantum cascade semiconductor laser to increase the intensity of collimated infrared light (5) and to lessen infrared light unnecessary for measurement, thereby improving the S/N ratio while achieving a rise in sensitivity. A plurality of analyte gases are simultaneously measured by means of a gas correlation filter comprising a reference gas cell (6a) filled with all of the analyte gases and a plurality of probe gas cells (6b) each individual of which is filled with all such analyte gases other than one of the analyte gases which is of its particular interest.

Abstract: A gas concentration measuring apparatus utilizing a gas correlation method capable of measuring concentrations of a plurality of analyte gases simultaneously and at high sensitivity uses an infrared light source (2) such as an infrared semiconductor diode or a quantum cascade semiconductor laser to increase the intensity of collimated infrared light (5) and to lessen infrared light unnecessary for measurement, thereby improving the S/N ratio while achieving a rise in sensitivity. A plurality of analyte gases are simultaneously measured by means of a gas correlation filter comprising a reference gas cell (6a) filled with all of the analyte gases and a plurality of probe gas cells (6b) each individual of which is filled with all such analyte gases other than one of the analyte gases which is of its particular interest.

Abstract: A method of estimating strength of forming photochemical ozone utilizing a pump and probe technique is disclosed along with an apparatus for estimating strength of forming photochemical ozone utilizing a pump and probe means whereby strength of forming photochemical ozone can be estimated without measuring a concentration of each type of various reactive hydrocarbons in order to predict strength of forming photochemical ozone from rates of their reaction with OH radicals. Atmosphere (11) is irradiated with a pumping laser light (2c) to photolyze ozone therein, thereby forming excited oxygen atoms O(1D) which are then caused to react with water vapor to form OH radicals. The OH radicals are irradiated with a probing laser light (3e) to excite electrons therein. A fluorescent light emitted when the excited electrons are relaxed to transition is measured in a time sequence.

Abstract: A method and apparatus for measuring the concentration of a trace nitrogen dioxide contained in the atmosphere on a pptv level with excellent accuracy by a single-wavelength laser induced fluorescence method. The device comprises a laser light source unit, a light excitation unit, a light guide unit, an air passing unit for passing either the air to be measured or a reference air prepared by removing nitrogen dioxide from the air to be measured, a light sensor unit and a control unit. A single-wavelength laser beam is applied to the air to be measured and the reference air. The intensity of the light emitted from the air to be measured and the intensity of the light emitted from the reference air are measured, and the concentration of nitrogen dioxide is determined by using the difference between the two.

Abstract: A method of and apparatus for determining a concentration of nitrogen dioxide that is contained as a trace constituent in atmospheric air utilizes a single-wavelength laser induced fluorescence technique whereby a nitrogen dioxide concentration as lows as at a pptv level can be determined conveniently and accurately.

Abstract: A method of estimating strength of forming photochemical ozone utilizing a pump and probe technique is disclosed along with an apparatus for estimating strength of forming photochemical ozone utilizing a pump and probe means whereby strength of forming photochemical ozone can be estimated without measuring a concentration of each type of various reactive hydrocarbons in order to predict strength of forming photochemical ozone from rates of their reaction with OH radicals. Atmosphere (11) is irradiated with a pumping laser light (2c) to photolyze ozone therein, thereby forming excited oxygen atoms O (1D) which are then caused to react with water vapor to form OH radicals. The OH radicals are irradiated with a probing laser light (3e) to excite electrons therein. A fluorescent light emitted when the excited electrons are relaxed to transition is measured in a time sequence.