Optical detectors developed on base of thermo elastic effect In quartz crystalline (PTEK) attributed to the thermal detectors group. Such detectors occurred very effective for the registration of pulsed light energy or power of harmonically modulated laser radiation flux in a wide spectral (from UV to far IR) and dynamic ranges (from 10-6 to 300 W / cm2 with cooling) with a time constant up to10-6 seconds. When exposed to electromagnetic radiation occurs at the receiver thermal field which causes mechanical stress in the transient crystalline quartz, which in turn leads to a change in the polarization of crystalline quartz and, as a consequence, to an electric potential difference at the electrodes (the front surface with a conductive coating and damper). The capacitive characteristic of the detector, based on a thermo elastic effect in crystalline quartz, eliminates the possibility of working with constant flow of radiation, which also affects at the frequency response of the detector, since the potential difference appearance in the piezoelectric plate depends on the direction of the forces relative to the axes X, Y, Z of the crystal. Therefore, a certain choice of orientation of the receiving element is necessary in accordance with the physical properties of crystalline quartz. In this paper, a calculation of the sensitivity and frequency characteristics of optical detectors based on the thermo elastic effect in crystalline quartz at the harmonic effects of electromagnetic radiation flux are reported.
Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01
The technical data on ozone gas analyzers which are currently produced and operate in Russia and the CIS countries for ozone concentration measurements in the lower atmosphere are presented. The specific requirements to this type of instruments are formulated and summarized data on their operating and accuracy characteristics are displayed. Some peculiarities of using optical and chemiluminescent ozone analyzers in view of providing minimum instrument error are discussed. An approach to reasonable combination of advantages of optical and chemiluminescent methods into one unique device are suggested and realized. The unique applications of some instruments under severe conditions of low temperatures in Antarctics on a ground based level and for measuring the ozone content vertical profile in the stratosphere up to 40 km are described. The perspective directions in developing ozone gas analyzers are discussed.
At present a number of ozone analyzer types with their own advantages and disadvantages are produced in Russia. Being wide in use the chemiluminescent ozone analyzers need a calibrator (ozone generator) with specified ozone concentration to compare with ozone concentration measured in the atmosphere. The authors describe a 2-beams UV photometer to graduate ozone generators. The instrument allows to measure background ozone concentrations in the ground layer of atmosphere. It has two equal absorption chambers (cells) switched alternately by two gas solenoid valves from the reference to measurement modes. The concentration value is determined by discrepancy.
An advanced type of ozone analyzer for measurement of ozone solved in water and aqueous solutions with different mud content levels has been developed. The operating principle of analyzer is based on the relationship between the balanced ozone concentration in a gas phase under solution and the gas concentration in the aqueous solution. Under solution and the gas concentration in the aqueous solution. Under isothermal condition this dependence can be described by the Henry equation. The ozone concentration in the gas phase is determined by a chemiluminescent method. The solid-state chemiluminescent sensor is operable under humidity of 100%. The range of measured concentrations is 25-25 000 ppm (0.05-5.00 mg/L).
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