We report a study of a semiconductor disk laser (SDL) based on the AlxGa1 – xAs/AlyGa1 – yAs heterostructure, emitting at a wavelength near 780 nm, pumped by a pulsed dye laser with emission wavelengths of 601 and 656 nm. Use is made of a structure with a built-in Bragg mirror and 10 quantum wells (QWs) arranged in depth with a period equal to half the wavelength of laser radiation in the structure. Under pumping with λ = 601 nm, a power of 9.3 W is reached at a wavelength of 782 nm with a differential efficiency of 12

The photophysical and photochemical properties of the protonated forms of both covalently bound biphotochromic dyad D44N containing two styrylbenzo[f]quinoline (SBQ) photochromes and corresponding cyclobutane CB44N containing two benzo[f]quinoline (BQ) substituents have been studied. CB44N is formed from D44N as a result of a reversible [2+2] photocycloaddition (PCA) reaction. The dyad and cyclobutane contain the 3-hydroxy-2-naphthoic acid (NA) moiety as a bridging group. It has been shown that the protonation of nitrogen atoms in the SBQ and BQ groups leads to bathochromic shifts in the absorption spectra and bathofloral shifts in the fluorescence spectra of the dyad and cyclobutane. In the protonated dyad, the quantum yield of the PCA reaction decreases, presumably due to the Coulomb repulsion, which prevents the cations of the protonated SBQ photochromes from approaching each other. In protonated cyclobutane, the quantum yield of the reverse four-membered ring opening reaction (retro-PCA), on the contrary, increases due to the absence of a competitive process of energy transfer from BQ to NA, which was previously observed in neutral cyclobutane.

Spectral, luminescent, and photochemical properties of 3-styrylbenzo[f]quinoline derivatives with a methoxy group in the 2-position (2MSBQ) and a methoxymethylene group in the 4-position (4MMSBQ) of the styryl moiety have been investigated. Both compounds luminesce in the range of 380–480 nm and undergo reversible photoisomerization with quantum yields of 0.2–0.5. The side reaction of photocyclization of the cis-isomer is observed for 2MSBQ in addition to photoisomerization. Upon protonation, photocyclization is blocked and both compounds undergo only photoisomerization, with the quantum yields of photoisomerization increasing and those of fluorescence decreasing. The absorption and fluorescence spectra shift bathochromically. Geometry and electronic structure of the compounds were calculated with the use of DFT by a B3LYP/6-31G* method. By calculation using the TD-B3LYP/6-31G* method and the analysis of the transitions between molecular orbitals, the observed differences in the absorption spectra of 2MSBQ and 4MMSBQ have been explained. The comparison of the obtained results with the SBQ derivatives studied earlier shows several interesting substituent effects, which are explained in terms of the diabatic mechanism of photoisomerization.

The photophysical and photochemical properties of the protonated form of an unsymmetrical biphotochromic dyad D2 containing derivatives of 3-styrylbenzo[f]quinoline (SBQ) as photochromes have been studied. In hydrochloride of the dyad, D2.2HCl, interphotochromic energy transfer is observed, whose efficiency, estimated from the data of fluorescence spectroscopy, is 92%. Under the action of light, hydrochloride D2.2HCl undergoes the photoisomerization reaction of SBQ photochromes. In addition, upon prolonged irradiation of D2.2HCl, side reactions additional to photoisomerization are observed, the main of which, according to mass spectral studies, are breaking the bridging ether bond CH2–O between two SBQ photochromes, and the addition of an ethanol molecule to the ethylene group of one of the photochromes. These reactions lead to the destruction of the dyad and prevent it from functioning as a photonic switch and a molecular logic gate.

Paramagnetic resonance of ZnSe: Fe single crystals was studied at 120 K. Parameters of the spin Hamiltonian were determined for the monoclinic dimer complex Fe3+–Cu+ and a second discovered Fe3+ center, which appears due to association of the iron ion with a K+ ion in a Zn2+ position or with a zinc vacancy. Effect of illumination of the zinc selenide samples by blue, green and red light on the paramagnetic resonance spectrum was investigated.

The experimental results of a mass spectral analysis of volatile organic compounds in a gaseous sample, obtained using an original design of an ion source based on the Penning ionization of a gas sample by excited metastable inert gas atoms, are presented. Using ANSYS software, a gas-dynamic simulation of reagent gas flow from discharge zone to ionization region was carried out to analyze the effect of gas flow profile on the transport of metastable atoms and ionization efficiency. The n -octane and toluene samples diluted with helium at 100 ppb mole concentrations were used for our experiments. The resulting mass spectra of n -octane and toluene samples containe far more intensive molecular ions in comparison to n -octane and toluene electron ionization mass spectra from the NIST database. The sensitivity of 5 ions per 1 pg and 130 ions per 1 pg was achieved for n -octane and toluene molecular ions using the developed ion source combined with our mass spectrometer. The corresponding detection limits are 2.3 pg s –1 for n-octane molecular ions and 0.08 pg s –1 for toluene molecular ions. The detection limit for the reported ion source was considered theoretically.

The electron paramagnetic resonance (EPR) spectra of iron-doped ZnSe single crystals were studied. In addition to cubic Fe 3+ and Mn 2+ centers and also Fe 2+ , and Cr 2+ centers, monoclinic Fe 3 + complexes locally compensated by Cu+ ions were revealed. Some trigonal centers with a spin of 3/2 were also found and studied. The zero-field splittings of monoclinic centers were measured, and the parameters of the monoclinic and trigonal spin Hamiltonians were determined. The nature of trigonal centers was discussed.

Исследованы спектры парамагнитного резонанса монокристаллов ZnSe, легированных железом. Кроме кубических центров Fe3+ и Mn2+, а также центров Fe2+ и Cr2+ обнаружены моноклинные комплексы Fe3+, локально компенсированные ионами Cu+. Также обнаружены и исследованы тригональные центры со спином 3/2. Измерены начальные расщепления моноклинных центров, определены параметры моноклинного и тригонального спиновых гамильтонианов. Обсуждается природа тригональных центров. Работа выполнена в рамках государственного задания Минобрнауки России для Уральского федерального университета (3.6115.2017/8.9), Программы президиума РАН 1.26 в КФТИ КазНЦ РАН и при поддержке Программы повышения конкурентоспособности НИЯУ МИФИ. Измерения проведены на спектрометре трехсантиметрового диапазона Центра коллективного пользования Современные нанотехнологии" Уральского федерального университета и высокочастотном перестраиваемом спектрометре Казанского физико-технического института. DOI: 10.21883/FTT.2017.10.44967.118

The work was aimed at assessing in vivo the analgesic properties of ten decahydroquinoline derivatives (pharmacologically active substances, PAS) and deter- mining the role of opioid receptors in mechanism of their action. Among the derivatives studied, pronounced analgesic properties at a dose of 1/4 LD50 was ob- served for two compounds (PAS-70 and PAS-71), while four compounds (PAS-66, PAS-69, PAS-74, PAS-76) produced weak and short anesthetic effects. PAS-70 and PAS-71 showed analgesic action even in a dose of 1/8 LD50. The maximum effect of PAS-70 and PAS-71 was developed within 20 - 60 min after administration and lasted for two hours (PAS-70 in a dose of 1/4 LD50, PAS-71 in doses of 1/4 and 1/8 LD50). The analgesic effect of PAS-70 (at 1/4 LD5,) and PAS-71 (at 1/4 and 1/8 LD50) significantly exceeds that of reference drugs metamizol (1/4 LD5) and ketorolac (1/4 LD50). The mechanism of drug action is not related to opioid receptors.

On the basis of low-temperature (5 K) microphotoluminescence measurements in a wide ZnSe/ZnMgSSe quantum well, the existence of isolated quantum emitters in this heterostructure is demonstrated. Characteristically, the corresponding emission lines experience stepwise spectral shifts by a few meV on a time scale of 1–10 min. The unconventional properties of the observed emitters are explained by considering the picture of a system with a large dipole moment in the ground state, such as a single donor–acceptor pair or a similar system located near an extended defect.

Pulse-periodic lasing at wavelengths of 2.8 and 3.3 µm is obtained in the Cr2+:CdSe single-crystal laser. In the region of 2.8 µm, the pumping conversion is 28% (more than 50% of the absorbed energy). In the region of 3.3 µm, lasing is achieved at several tunable narrow lines appropriate for using in remote lidars. The pumping conversion in this spectral region is more than 17% (more than 30% of absorbed energy).

The objective of this work is the study of the ion mobility dependence of electrospray Gramicidin S ions [M + 2H]2+ on the ion bunch drift velocity under variation of the specific electrical field strength at certain gas number density in the range from 0 to 300 Td. The ion mobility measurements were carried out under rotational excitation of ions using custom built gas filled segmented radio frequency quadrupole with the nitrogen buffer gas pressure of 1.9 Pa. The resulting ion mobility dependence of [M + 2H]2+ Gramicidin S ions upon the bunch drift velocity is essentially weaker, than it could be expected from the hard sphere collision model. By comparing the acquired ion mobility dependencies with the theoretical ones derived from the hard sphere collision model we suppose that the attractive polarization potential takes an essential part into the ion-molecular interaction even for such big organic ions as Gramicidin S.

The exciton states in Zn(Cd)Se/ZnMgSSe quantum wells with various degrees of diffusive spreading of interfaces are studied by optical spectroscopy methods. Luminescence lines of free excitons are identified. It is shown that, in addition to exciton level shift, heterointerface spreading enhances exciton-phonon coupling and increases the energy shift between maxima of emission lines of free and bound excitons. The major causes of the observed phenomena are discussed.

An output power of 0.85 W with a differential efficiency with respect to absorbed pump power of 55.4% is achieved for a Cr2+:CdSe laser with a wavelength of 2.6 µm under optical pumping with a semiconductor disk laser with a wavelength of 1.98 µm.

A three-dimensional numerical model of a diode laser with a resonant grating of quantum wells (QWs) and an external mirror is developed and used to calculate diode laser pulses that are long compared to the time of reaching a stationary regime and are short enough to neglect heating of the medium. The consistent solutions of the Helmholtz field equation and the system of diffusion equations for inversion in each QW are found. A source of charge carriers can be both an electron beam and a pump laser beam. The calculations yielded the longitudinal and radial profiles of the generated field, as well as its wavelength and power. The effective threshold pump current is determined. In the created iteration algorithm, the calculation time linearly increases with the number of QWs, which allows one to find the characteristics of lasers with a large number of QWs. The output powers and beam divergence angles of a cylindrical laser are calculated for different cavity lengths and pump spot radii. After calculating the fundamental mode characteristics, high-order modes were additionally calculated on the background of the frozen carrier distributions in the QW grating. It is shown that all the competing modes remain below the excitation threshold for the pump powers used in the experiment. The calculated and experimental data for the case of pumping by a nanosecond electron beam are qualitatively compared.

Cleavages of undoped nanoscale heterostructures with GaInP/AlGaInP and CdS/ZnSSe quantum wells were studied by scanning probe microscopy. A nanorelief formed on the cleavage surface due to elastic stresses in quantum wells was detected by contact methods. The current method yielded more contrast images. It was shown that the current in undoped heterostructures depends on the Schottky barrier on the probe contact with structure layers, the intrinsic carrier concentration in them, the growth substrate doping level, the intensity and spectrum of external illumination.