The patterns of catalytic ignition of deuterium–air mixtures above the surface of metallic rhodium at pressures of 1–2 atm and temperatures of 20–250°C using hyperspectrometers in the range of 400–1650 nm and high-speed filming have been established. It is established that the catalytic ignition of deuterium–air mixtures in the studied temperature range is observed at a deuterium content of more than 12

The structure of a device designed to detect X-ray and optical photons ascending from a sample irradiated with synchrotron radiation or X-ray tube radiation and the principles of its operation are described. The operation of the device consists of determining the delay time of the specified optical photons relative to the X-ray photons. Block diagrams of the main components of the device, outlining the principles of their operation, are given: a monophoton X-ray sensor, a monophoton optical sensor, and a unit for determining the time delay. The areas of scientific and applied use of information obtained with the help of the considered device are indicated.

Ультрафиолетовый (УФ) С-диапазон обеспечивает высокую помехоустойчивость и возможность работы аппаратуры в тропосфере в дневное время, так как озоновый слой атмосферы практически полностью поглощает УФ-С-излучение Солнца. Одним из главных преимуществ этого диапазона в сравнении с видимым, инфракрасным и даже радиодиапазоном является слабое рассеяние ультрафиолета на аэрозольных частицах пыли, снега, града, водяных каплях тумана и дождя. В настоящей работе предложен метод определения оптической толщины атмосферы при распространении УФ-С-излучения по наклонной трассе над морем. Учет неоднородности трассы распространения УФ-С-излучения обеспечивается посредством введения в модель зависимости коэффициента экстинкции и оптической толщины атмосферы от высоты. Справедливость предложенной модели подтверждена данными натурного эксперимента, проведенного над акваторией Черного моря. На основании экспериментальных данных определены коэффициент экстинкции атмосферы над морской поверхностью и его аэрозольная и молекулярная составляющие.

Приводится описание структуры и принципов функционирования устройства, предназначенного для детектирования рентгеновских и оптических фотонов, исходящих от образца, облучаемого синхротронным излучением или излучением рентгеновской трубки. Работа устройства заключается в определении времени задержки указанных оптических фотонов относительно рентгеновских. Приведены блок-схемы основных узлов устройства: монофотонного датчика рентгеновского излучения, монофотонного датчика оптического излучения и блока определения временнóй задержки с изложением принципов их функционирования. Указываются области научного и прикладного использования информации, получаемой с помощью рассматриваемого устройства.

The ultraviolet (UV)-C range ensures high noise immunity and the possibility of operating equipment in the troposphere during the daytime, since the ozone layer of the atmosphere almost completely absorbs the UV-C radiation from the Sun. One of the main advantages of this range in comparison with the visible, infrared, and even radio range is the weak scattering of ultraviolet on aerosol particles of dust, snow, hail, water droplets, fog, and rain. In this paper, we propose a method for determining the optical thickness of the atmosphere during the propagation of UV-C radiation along an inclined path over the sea. Accounting for the inhomogeneity of the path of propagation of UV-C radiation is ensured by introducing in the model the dependence of the extinction coefficient and the optical thickness of the atmosphere on altitude. The validity of the proposed model is confirmed by the data of a full-scale experiment conducted over the Black Sea. The extinction coefficient of the atmosphere above the sea surface, as well as its aerosol and molecular components, is determined based on the experimental data.

— In experiments on the ignition of the stoichiometric mixture of hydrogen and oxygen over strips of palladium and platinum foil at a total pressure of up to 200 Torr and initial temperature up to 300°C, the temperature of the foils during ignition was measured using an infrared camera and data on temperature dependence of metal resistivity. The temperature of the ignition initiated at 40 Torr over a heated palladium foil was shown to be ~100°C lower than that over a platinum foil. Even the minimal measured foil temperature (623°C) is sufficient to ignite the explosive mixture, implying that the influence of a catalytic reaction of hydrogen oxidation over the noble metals is insignificant in the case of initiated ignition. The presence of water vapor was found to prevent ignition. In the case of thermal ignition, it was found out that at a pressure of up to 180 Torr and 288°C the catalytic activity of the palladium foil is significantly higher than that of the platinum foil. The palladium foil activity is manifested in the competition of two processes: the emergence of local ignition centers on the foil, from which a combustion wave propagates, and a dark catalytic reaction of transformation of the explosive mixture into water.

The effect of difluorodichloromethane additives on spark-discharge-initiated combustion of hydrogen and methane in air and oxygen media at atmospheric and reduced pressures has been investigated. It was found that the concentration limit of ignition of a premixed hydrogen–air mixture in the presence of difluorodichloromethane at 1 atm exceeds 10%. It was shown for the first time that the ignition limit of a premixed methane–air mixture is 1% of difluorodichloromethane, which is thus the most effective inhibitor of methane combustion. This also means that the active centers of hydrogen and methane combustion, which determine the development of combustion, have different chemical natures. Thus, the reaction with the participation of a difluorodichloromethane molecule leading to the formation of HF (ν = 2, 3) during the combustion of methane must include a stage with the participation of an active intermediate substance of methane combustion. Vibrationally excited HF molecules (ν = 2, 3) were first detected in products of hydrogen and methane oxidation reactions in the presence of difluorodichloromethane using visible and near-infrared hyperspectrometers. It has been established for the first time that HF molecules (ν = 3) during methane combustion are formed at the moment of reaching the maximum rate of chemical transformation; i.e., reactions involving CF2Cl2 molecules compete with the development of reaction chains.

For the first time, vibrationally excited HF molecules (v = 2, 3) are observed with the use of hyperspectrometers in the VIS and NIR ranges in the products of the reactions of oxidation of hydrogen and methane in the presence of Difluorodichloromethane (CF2Cl2). The combustion of hydrogen and methane in air and oxygen at atmospheric and reduced pressure is initiated by a spark discharge. The propagation of the flame front is recorded using high-speed color filming. It is found that during the combustion of methane HF (v = 3) molecules are formed at the moment of reaching the maximum rate of the chemical transformation, i.e., reactions involving CF2Cl2 molecules compete directly with the development of reactive chains. It is also found that the concentration limit of the ignition of a premixed hydrogen-air mixture in the presence of Difluorodichloromethane at a pressure of 1 atm exceeds 10% CF2Cl2, while the concentration limit of the ignition of a premixed methane-air mixture is 1% CF2Cl2. This means that the active centers of the combustion of hydrogen and methane, which determine the development of combustion, have a different chemical nature. It is shown that the set of reactions involving Difluorodichloromethane molecules, leading to the formation of HF (v = 2, 3) during methane combustion, should include active centers of methane combustion.

The effect of difluorodichloromethane additives on spark initiated combustion of hydrogen and methane in air and oxygen at atmospheric and reduced pressures was investigated. It has been found that the ignition concentration limit of the premixed hydrogen-air mixture in the presence of difluorodichloromethane at 1 atm exceeds 10%, while it has been shown for the first time that the ignition limit of the premixed methane-air mixture is 1% of difluorodichloromethane, which is thereby the most effective methane combustion inhibitor. This also means that the active combustion centers of hydrogen and methane, which determine the development of combustion, have a different chemical nature. Thus, the reaction including a difluorodichloromethane molecule resulting in the formation of HF (v = 2.3) during methane combustion should include a step involving the active methane combustion intermediate. Using hyperspectrometers of the visible and near-infrared ranges in the products of the oxidation reactions of hydrogen and methane in the presence of difluorodichloromethane, vibrationally excited HF molecules (v = 2.3) were first discovered. For the first time, it was found that HF molecules (v = 3) during methane combustion are formed at the moment when the maximum rate of chemical conversion is achieved, that is, reactions involving inhibitor molecules compete with the process of development of reaction chains. Keywords: chain burning, inhibition, methane, hydrogen, dichlorodifluoromethane, hyperspectrometer, high-speed color filming, radicals, excited particles.

One of the most important tasks of chemical physics of the atmosphere is the operational monitoring of the current state of the atmosphere and ionosphere, the results of which are important for the study of solar-terrestrial relationships and the solution of many applied problems. This paper presents the concept of forming a complex of scientific equipment (CSE) proposed for placement on a small satellite. The onboard complex is designed to monitor a wide range of objects: the solar disk, the Earth’s limb, transient phenomena, the state of the ozone layer, the Earth’s surface, etc. The tactical and technical characteristics of the instrumental composition of the complex are described in detail, including a UV telescope of the Sun, ultraspectrometer of the Earth’s limb, UV sensor of the Earth’s ozone layer, hyperspectrometer of the atmosphere and Earth’s surface, and a UV-C sensor of transient light phenomena.

In this paper, we report the results of studying the combustion characteristics of fuels containing a hydrogen–hydrocarbon (C 1 –C 6 , as in CH 4 , C 2 H 6 , C 3 H 8 , C 4 H 10 , C 5 H 12 , and C 6 H 14 ) mixture with a fuel fraction of 0.6–1.2 in a mixture with air above the palladium surface at a total pressure of 1–2 atm. The propagation features of the flame front in mixed fuels are revealed, and the temperature dependences of the ignition limit over the palladium surface are determined. The observed separation of the CH and Na emission bands in time during the combustion of the 30% propane + 70% H 2 + air mixture (the fuel fraction in the mixture with air is unity) was established to be caused by the occurrence of hydrodynamic instability of the flame when it touches the end of a cylindrical reactor.

A new automated system for controlling crystallization setups, providing their reliable operation and remote control, has been developed. The principles of constructing a system controlling many setups for growing crystals from low-temperature solutions and its functioning are described.

The ignition temperature of the 40% H2 + air mixture in the presence of metallic palladium (70°C, 1 atm) was found to be ~200°C lower than above the platinum surface (260°C, 1 atm). In addition, Pd initiated the ignition of (30–60% H2 + 70–40% CH4)stoich + air mixtures at temperatures below 350°C, while Pt foil did not initiate the burning of these mixtures up to 450°C. The effective activation energy of ignition over Pd was evaluated to be ~3.5 kcal/mol. It was found using a hyperspectral sensor that the system of emission bands of H2O* was absent in the range 570–650 nm in the presence of leucosapphire; a possible explanation of this phenomenon was given. An explanation was proposed for the appearance of an additional source of excited water molecules emitting in the range 900–970 nm.

The results of the experimental study of the passage of UV-C radiation (with a spectral range from 100 to 280 nm) through the atmosphere are presented, and these data on the passage of solar radiation through the atmosphere is compared with those obtained using the MODTRAN program.