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Your search keyword '"Lednev, V. N."' showing total 193 results
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193 results on '"Lednev, V. N."'

2. Air ions induced aerosol sensing by eye-safe LIDAR

Author

Pershin, S. M., Zavozin, V. A., Grishin., M. Ya., Lednev, V. N., Boldin, G. A., Bezrukov, L. B., Mezhokh, A. K., and Sinev, V. V.

Subjects
Physics - Atmospheric and Oceanic Physics, Physics - Optics
Abstract

Low concentrations aerosols quantification is rather challenging for LIDAR instruments due to eye-safety restrictions so high energy pulses cannot be utilized to improve the sensitivity. Highly sensitive but eye-save LIDAR has been developed for the quantification of the water droplet aerosol which was induced by air ions. Few days sensing of aerosols in closed tunnel revealed a strong correlation between air optical transparency (LIDAR measurements) and concentrations of positive/negative ions (ion counter Sapphir 3-M). The correlation coefficient was observed to be almost unity for the air transparency signal and air ions unipolarity coefficient. High sensitivity of the water droplet aerosol quantification makes the developed eye-safe LIDAR a perspective instrument for space resolved measurements of the air ions distribution. Space and time resolved measurements of air ions exhalation can be a new instrument for tectonic activity study including new earthquake forecasting indicators search.

Published
2023

10. Laser excitation of gigahertz vibrations in Cauliflower mosaic viruses suspension

Author

Tcherniega, N. V., Pershin, S. M., Bunkin, A. F., Donchenko, E. K., Karpova, O. V., Kudryavtseva, A. D., Lednev, V. N., Mironova, T. V., Shevchenko, M. A., Strokov, M. A., and Zemskov, K. I.

Subjects
Physics - Optics
Abstract

The interaction of laser pulses with the Cauliflower mosaic virus (CaMV) in a Tris-HCl pH7.5 buffer is investigated. 20 ns ruby laser pulses are used for excitation. Spectra of the light passing through the sample and reflected from it are registered with the help of a Fabri-Perot interferometer. Stimulated low-frequency Raman scattering (SLFRS) in a CaMV suspension is registered. The SLFRS frequency shift, conversion efficiency and threshold are measured for the first time, to the best of our knowledge., Comment: 6 pages, 3 figures

Published
2018
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11. Laser induced breakdown spectroscopy for multielement analysis of powder materials utilized in additive technologies

Author

Lednev, V. N., Sdvizhenskii, P. A., Grishin, M. Ya., Davidov, M. A., Stavertiy, A. Ya., Tretyakov, R. S., Taksanc, M. V., and Pershin, S. M.

Subjects
Physics - Applied Physics
Abstract

Powder materials utilized in additive technologies were quantitatively analyzed by laser induced breakdown spectroscopy for the first time. Laser induced breakdown spectroscopy mapping of loose metal powder attached to the double-sided adhesive tape provided high reproducibility of measurements even for powder mixtures with large difference of particles densities (tungsten carbide particles in nickel alloy powder). Laser induced breakdown spectroscopy analytical capabilities for tungsten and carbon analysis were estimated by calibration curve construction and accuracy estimation by leave-one-out cross-validation procedure. Laser induced breakdown spectroscopy and X-ray fluorescence spectroscopy techniques comparison revealed better results for laser induced breakdown spectroscopy analysis. Improved accuracy of analysis and capability to quantify light elements (carbon etc.) demonstrated large perspectives of laser induced breakdown spectroscopy as a technique for express on-site multelement analysis of powder materials utilized in additive technologies.

Published
2018
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12. Induced crystallization method of rapid metal melts 3d-printing

Author

Oshurko, V. B., Lednev, V. N., Mandel, A. M., and Solomakho, K.

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

A solution for the most important problems in 3D printing technology (long print times, small build volumes and limited material properties) is proposed. Method is based on the fact that temperature of melts crystallization can be shifted up by pressure. Required pressure can be created by Ampere force caused by electric current in the melt flow. Magnetohydrodynamical model (with heat taken into account) is developed. It has been shown that additional heating of melt by this current can be overcome by appropriate choice of tunable parameters and introduction of some additional magnetic field. Range of parameters where this induced crystallization can take place is found.

Published
2018

17. Stimulated low-frequency Raman scattering in tobacco mosaic virus suspension

Author

Karpova, O V, Kudryavtseva, A D, Lednev, V N, Mironova, T V, Oshurko, V B, Pershin, S M, Petrova, E K, Tcherniega, N V, and Zemskov, K I

Subjects
Physics - Optics
Abstract

Laser pulses interaction with tobacco mosaic virus (TMV) in Tris-HCl pH7.5 buffer and in water has been investigated. 20 ns ruby laser pulses have been used for excitation. Spectrum of the light passing through the sample was registered with the help of Fabri-Perot interferometer. In the case of TMV in water we observed in the spectrum only one line of the exciting laser light, for TMV in Tris-HCl pH7.5 buffer second line appeared, corresponding to the stimulated low-frequency Raman scattering (SLFRS) on the breathing radial mode of TMV. SLFRS frequency shift by 2 cm-1, (60 GHz), conversion efficiency and threshold are measured for the first time to the best of our knowledge., Comment: 7 pages, 3 figures, accepted for publication in Laser Physics Letters

Published
2016

49. Laser-induced luminescence of boron-doped synthetic diamond at various laser pulse durations

Author

null Khmelnitsky R. A., null Bondarenko M. G., null Tarelkin S. A., null Kuznetsov M. S., null Sdvizhenskii P. A., null Lednev V. N., null Danilov P. A., and null Oleynichuk E. A.

Abstract

Excitation of type IIb synthetic diamond by ultrashort laser pulses in the visible range causes broadband luminescence in the UV visible range; the observed luminescence band can be attributed to the A band characteristic of diamonds. The photoluminescence spectra were obtained at different laser pulse durations (0.3-6.2 ps) depending on the pulse energy. A nonlinear dependence of the luminescence yield on the intensity of ultrashort pulses is established. Keywords: broadband luminescence, boron doped diamond, two-photon luminescence, A-band.

Published
2022
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