Внутридоплеровские резонансы, обусловленные фотоионизацией атомов в тонких газовых ячейках

By analogy with the well-tested method of high-resolution spectroscopy in thin gas cells for the processes of optical pumping of atoms, this work shows the possibility of detecting narrow sub-Doppler optical resonances caused directly by straight photoionization of atoms (or molecules) in such cells. The structure of the established nontrivial resonances substantially depends on the probability of photoionization of atoms and dimensions of such a cell, the internal thickness of which is many times smaller than its diameter. Of particular interest is the broadening of the considered sub-Doppler resonances, which is determined directly by the photoionization cross section of atoms and the intensity of radiation causing ionization. Under certain conditions, such photoionization broadening can be measured experimentally with high accuracy, as a result of which it is possible to obtain new important information about ionization processes in atoms and molecules.

Lowest-Order Thermal Correction to the Hydrogen Recombination Cross-Section in Presence of Blackbody Radiation

In the present paper, the correction of the recombination and ionization processes of the hydrogen atom due to the thermal interaction of two charges was considered. The evaluation was based on a rigorous quantum electrodynamic (QED) approach within the framework of perturbation theory. The lowest-order radiative correction to the recombination/ionization cross-section was examined for a wide range of temperatures corresponding to laboratory and astrophysical conditions. The found thermal contribution was discussed both for specific states and for the total recombination and ionization coefficients.

Mass Spectrometry and Its Importance for the Analysis and Discovery of Active Molecules in Natural Products

Mass spectrometry is one of the best techniques for analyzing the structure of a molecule. It usually provides information about the molecular weight of a substance, and it can present atomic mass units and up to ten thousandths of atomic mass units depending on the accuracy of the mass analyzer. In addition, it provides information on the positive ions formed in the ionization process, which is linked to the chemical structure of the molecule and the nature of the bonds. This technique is widely used for analyzing compounds from natural products. The development of the technique combined with the use of software and databases has been remarkable in recent years, improving the ionization processes and the ion analysis. Since natural products generally constitute a mixture of a complex quantity of components, mechanisms have been developed for coupling to chromatographic techniques of various kinds. This review aims to show how mass spectrometry has contributed to the qualitative quality control in natural products, as well as in the finding of new metabolites of industrial interest.

Measurement of the sound velocity of shock compressed water

The sound velocities of water in the Hugoniot states are investigated by laser shock compression of precompressed water in a diamond anvil cell. The obtained sound velocities in the off-Hugoniot region of liquid water at precompressed conditions are used to test the predictions of quantum molecular dynamics (QMD) simulations and the SESAME equation-of-state (EOS) library. It is found that the prediction of QMD simulations agrees with the experimental data while the prediction of SESAME EOS library underestimates the sound velocities probably due to its improper accounting for the ionization processes.

Low-energy constraints on photoelectron spectra measured from liquid water and aqueous solutions

We report on the effects of electron collision and indirect ionization processes on the photoemission spectra of liquid water, specifically at photoexcitation and electron kinetic energies well below 30 eV.

Моделирование реакции сверхвысокочастотного низкобарьерного неохлаждаемого диода Мотта на воздействие тяжелых заряженных частиц космического пространства и фемтосекундных лазерных импульсов

A theoretical analysis of the degradation of the current-voltage characteristic and transient ionization processes occurring in a low-barrier uncooled GaAs Mott diode under the action of heavy ions of outer space and laser pulses simulating them is carried out. The response of the diode to the action of an arsenic ion with an energy of 200 MeV, corresponding to a linear energy transfer of 26 MeV∙cm2/mg, is compared with the response to the action of femtosecond pulses of optical radiation with a duration of 10 fs with a wavelength of 870 nm and 670 nm.