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In the Arctic zone of Siberia, large diamond occurrences have been discovered in volcaniclastic, sedimentary-volcaniclastic, volcanosedimentary, and sedimentary rocks of the upper Ladinian strata and the base of the Carnian (Triassic) strata. They are confined to the Primorye mineragenic zone, which is traced along the Laptev Sea water area from the western Verkhoyansk area to eastern Taimyr. We have first identified a specific range of diamonds in these deposits. Among the rounded crystals of varieties I, II, V, and VII, there are grains with a light carbon isotope composition and high nitrogen contents. They have no analogues in typomorphic features in the known primary deposits of Yakutia but are completely similar to diamonds in the Rhaetian, Early Jurassic, Late Jurassic, Early Cretaceous, Neogene, and Quaternary commercial placers and placer occurrences, which suggests their formation as a result of the erosion of Triassic sources.

Pyrolysis-free gas chromatography-mass spectrometry was used to determine the gas phase composition of inclusions in phenocrysts from basalts and rhyolites of the Men’shii Brat Volcano (Medvezh’ya caldera, Iturup Island). Among more than 300 compounds detected in the inclusions, hydrocarbons are predominant (52-92 rel.%). These hydrocarbons (С₁-С₁₇) are alkanes, alkenes, alcohols, polycyclic aromatic hydrocarbons, ethers and esters, aldehydes, ketones, and carboxylic acids as well as sulfonated, nitrogenated, and halogenated organic compounds. Inorganic substances, which are predominantly CO₂, H₂O, SO₂, and N₂, are present in subordinate amounts. The organic compounds are interpreted as products of abiogenic synthesis of hydrocarbons in magmatic gases. This fundamentally new information about the composition of magmatic fluid suggests that mantle and crustal magmas can transport hydrocarbon substance.

The calculated line intensities of the 1-0, 2-0 and 3-0 absorption bands of the radioactive hydrogen chloride isotopologue H³⁶Cl are presented. The line positions were calculated using the Dunham coefficients obtained with the help of the isotopic independent spectroscopic constants. The line intensities of these bands were calculated using the effective dipole moment parameters obtained with the help of the isotopic substitution equations based on the effective dipole moment parameters of the H³⁵Cl isotopologue. The latter were fitted to the line intensities presented in the HITRAN2020 database.

The methane spectrum is studied near R (3) and R (4) multiplets of the first vibrational overtone in the 298-720 K temperature range with a tuning diode laser. We have developed the technique for laser radiation measurement and frequency calibration with the use of a high-stability plain-mirror interferometer. The coefficients of collisional broadening by nitrogen are calculated at different temperatures.

The results of experimental studies of absorption spectra of pure NH₃ at room temperature in the ranges 6604.3-6606.3 and 6611.6-6613.5 cm^-1 and pressure of up to 0.04 atm are presented. The measurements were carried out at the Department of Diode Laser Spectroscopy of the Institute of General Physics at a high-sensitivity high-resolution diode laser spectrometer with a signal-to-noise ratio of ~ 1400. The spectra were analyzed using a Voigt contour. The results of retrieving the parameters of spectral absorption lines are presented: the positions of centers, intensities, and coefficients of collisional self-broadening and shifts. A comparison was made with the parameters from HITRAN database. A two-fold difference between the measured intensities of a number of lines and the HITRAN values was found.

The absorption spectrum of stable dimers in the long-wave wing of the rotation H₂O band is estimated proceeding from available experimental data on the H₂O continuum absorption in this region and calculations on the basis of the asymptotic line wing theory. The spectral line contour of the rotational band describing the spectral and temperature behavior of the H₂O continuum absorption in the 8-12 mm range was used in the calculations. The spectrum derived does not conflict with computations with the dimer model of the continuum absorption.

Nitric acid plays an important role in atmospheric chemistry; therefore, it is currently monitored by various methods and instruments. Ground-based FTIR method based on spectral measurements of solar radiation by Bruker Optics IFS 125HR spectrometers allows to retrieve not only the total column HNO₃, but also its content in several atmospheric layers. We analyze time series of HNO₃ measurements at St. Petersburg NDACC site between 2009 and 2021. We demonstrate that FTIR measurements can provide information on HNO₃ content in at least two atmospheric layers; the degrees of freedom for signal in average totals 3.1. The mean random error of HNO₃ measurements amount to 3.9, 14 and 1.6% for total atmospheric, tropospheric (up to 15 km), and stratospheric (above 15 km) content, respectively. Thus, the FTIR-method considered is more sensitive to changes in the stratospheric HNO₃ content. The absorption of solar radiation by nitric acid in the measured spectra overlaps with the absorption by water vapor; therefore, the information content and accuracy of HNO₃ measurements are maximal in winter and minimal in summer: in winter, measurements are carried out mainly at low sun and low humidity, and in summer, vice versa.

The results of a comparison of the time series of the turbulent mixing layer height, which is determined from the height-time distributions of the kinetic energy dissipation rate of turbulence and from the height-time distributions of the gradient Richardson number are presented. It is found that only under conditions of atmospheric boundary layer instability due to convection, estimation of the height of the turbulent mixing layer from the height-time distributions of the Richardson number gives results close to those obtained from the distributions of the kinetic energy dissipation rate of turbulence. In other cases, the height of the mixing layer found from the Richardson number can be significantly underestimated.

The phenomenon of reflection of light radiation from crystalline particles oriented in the atmosphere, as well as the physical laws and possible conditions contributing to its occurrence, are considered. A variant of registration of mirror layers using a panoramic optical station (AllSky system) is described.

The time and space derivatives of the air temperature and its products with the wind vector components are analyzed for the cases where the temperature and wind fields are resolved into the deterministic, meso-gamma scale, and turbulent parts. Ultrasonic thermoanemometer measurements in the surface air layer are used for the analysis. The variability ranges of the derivatives are estimated including meso-gamma scale variations in the temperature and wind fields. The variability ranges of these derivatives are compared with those of the “classical” derivatives (when only deterministic and turbulent parts are considered). The derivatives of the components which contain meso-gamma scales are shown to be comparable with the components which include only turbulent parts.