B. G. Ageev

Laser two-channel gas analyser

The technical scheme of a remote laser analyser of vapours of hazardous and toxic substances based on two IR sources (a tunable 13C16O2 isotope laser and a quantum cascade laser) is described. The developed optical scheme of the analyser, which is identical for both sources, makes it possible to fabricate a rather compact device. The use of two channels considerably extends the application field of the gas analyser. The possibility of using the gas analyser in stationary and mobile variants is provided.

Remote detector of hazardous substances based on a tunable 13С16О2 laser

A description of the developed prototype of a remote detector of hazardous substance vapors based on a tunable 13С16О2 laser is given. Results of test measurements of laser radiation transmission of organic liquid vapors (acetone, ammonia, ethanol, gasoline) are presented. The remote detection of acetone and ammonia vapors at distances up to 100 m is experimentally implemented.

Attenuation of Terahertz Radiation Region by Water Aerosol

Measurement results on energy attenuation of terahertz radiation of a free-electron laser by a model air-aerosol medium are presented. Spectral and concentration dependencies of the radiation attenuation are studied. It is shown that under actual experimental conditions the attenuation is conditioned by aerosol particles.

Remote detection of gas markers of artificial explosives

At the recent years, the increasing interest to laser methods of detection of harmful and dangerous admixtures in the open atmosphere is observed. In this work, experimental results are given of remote detection of acetone vapors, which is the marker of triacetone triperoxide (TATP), with the use of the frequency-pulse 13С16О2 laser with generation line at 11.2 μm.

Detection of the local volume of chemical elements on extended atmospheric paths: Model experiment

Laboratory experiments on the detection of vapors of chemical compounds (acetone and hydrogen peroxide) localized at a small length of 0.62 m on a model atmospheric path of 220 m have been performed. The experimental and calculated data have been compared. The possible fields of the application of the designed experimental bench are discussed.

Photoacoustic spectroscopy of the expired air at a human respiratory pathology

There are about 600 volatile compounds in air expired by man, including molecules-biomarkers of endogenous (produced in organism) origin, the specificity of generation and excretion mechanisms of which is sufficient for studies of both normal and pathologic processes. The goal of this work is analysis of the human-expired air by means of the intracavity laser photoacoustic sensor intended for detection of air gas admixtures having the absorption bands in the wavelength spectral range 9.2 - 10.8 μm. The sensor principle of operation is based on the photoacoustic effect caused by gas absorption of the CO2 laser radiation. Measurements were conducted with a test group consisting of 100 persons and a group of patients (60 persons) affected by different bronchopulnionary pathologies. The state of health of each group members was determined from questioning data. The spectral absorption dependences were normalized to referent points and then investigated in respect to a qualitative coincidence. The typical results are presented below.

Laser photoacoustic detection of CO2 in biosphere-atmosphere gas exchange and in tree rings

The method and technology of the photoacoustic gas analysis enables highly sensitive investigations of CO2 gas exchange different biosystems. The CO2 evolution by some plants exposed to elevated concentration of pollutants and CO2 emissen from the wood of tree rings at low air pressure is studied. All measurements have been performed using the photoacoustic gas analyzer with the tunable CW CO2-laser.

Dynamics of CO2 evolution by plants at low pressure

Dynamics of CO2 evolution at low pressure was studied in barley, maize, pea, wheat and pine seedlings using the gas exchange system with laser photoacoustic spectrometer. The CO2 evolution from plant surfaces to environment increased with decreasing air pressure. Simultaneously the changes in activities of phosphoenolpyruvate carboxylase, glucose-6-phosphate dehydrogenase, glyceraldehyde phosphate dehydrogenase, alcohol-dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase in pea and maize leaves were observed. The response depended on plant species used as well as on air pressure and period of its action

Absorption of pulsed CO2 laser radiation by air and carbon dioxide

An optoacoustical method is used in experimental study of nonlinearity in absorption of pulsed CO2 laser radiation by air with CO2 and H2O added and pure CO2. The laser pulse consists of frequencies related to several rotational transitions, generated simultaneously. Nonlinearity in absorption was detected for laser radiation levels above 0.2 MW/cm2.