A. I. Demin

Far-infrared radiation effect on the structure and properties of proteins

This paper describes the effect of far-infrared radiation on the activity and secondary structure of albumin, alcohol dehydrogenase, peroxidase and trypsin. For the first time the data obtained allowed a conclusion that enzymatic activity changes under the influence of radiation having the wavelength of 90 μm. No disruptures of polypeptide chains or oligomerization of proteins were obtained. It has been shown that albumin secondary structure calculated from circular dichroism spectra changes lineary according to dose of laser emission.

Experiment with a cw N2O gasdynamic laser and its qualitative comparison with a CO2 laser

Preliminary experimental data concerning an N2O/N2 thermally excited and selectively pumped mixing cw gasdynamic laser are reported and compared with those concerning a CO2/N2 laser operating at similar conditions.

Analysis of data on the vibrational-relaxation constants in CO2−N2−H2O mixtures, and optimization of a gasdynamic CO2 laser

The optimum stagnation parameters and compositions of the C02-N2-H20 mixture are optimized on the basis of data on the vibrational-relaxation constants. The influence of the uncertainty in the relaxation constants on the optimization results is analyzed.

Simplified calculations for prediction of parameters of 18.4‐μm CO2 continuous‐wave gasdynamic lasers

A simplified analytical model of the CO2 cw gasdynamic laser operating on the Q branch of the 0310?1000 radiative transition is presented in this paper. The population inversion, gain, and maximum available vibrational energy to be converted into the 18.4‐μm wavelength radiation field are calculated together with corresponding values of the temperature(s), pressure(s), nozzle cross‐section area(s), and laser output per unit mass flow in an ideal adiabatic approximation. The influence of the relaxation of the coupled ν1 and ν2 vibrational modes and of the cavity losses on the laser output power are considered.

Shock‐tube CO2 gas‐dynamic laser operating on the (0310)⇄(10°0) transition at 18.4 μm

Laser action at 18.4 μm has been obtained between the (0310) and (1000) levels in a shock‐tube‐driven CO2/Ar gas‐dynamic laser. The pulse duration was equal to about 4 ms, giving the output power up to 2 W extracted from a 10‐cm3 volume cavity mounted within a nozzle of 60° divergence angle and 0.5‐mm throat height 67‐mm downstream of the nozzle throat.

Low‐stagnation‐temperature characteristics of cw N2O and CO2 gasdynamic mixing lasers pumped by nitrogen or air

Experimental data collected from a N2O/N2(air) thermally excited and selectively pumped cw gasdynamic mixing laser are reported for a range of low stagnation temperatures and compared with data from a CO2/N2(air) laser. Lasers operating with air yield practically identical output as with usual nitrogen pumping.

Saturation parameter and small‐signal gain of cw CO2 and/or N2O mixing gasdynamic lasers

The small‐signal gain of cw CO2 and/or N2O mixing gasdynamic lasers has been measured by varying the cavity losses with the aid of two rotating coupled NaCl plates placed within the cavity and looking for the generation cutoff point. The saturation parameter has been determined on the basis of measured values of respective small‐signal gains by experimentally recovering the output power‐cavity losses relation. The measurements yielded α0≃1.1 m−1 and Is≃3.2 kW/cm2 for CO2, and α0≃1.0 m−1 and Is≃3.0 kW/cm2 for a cw N2O mixing gasdynamic laser.

Study of the appearance of IR pulsed laser generated wave of reflection and conduction as detected in polycrystal high-temperature superconductors

We present the reflection investigation results for the first stage of the Reflection and Conduction Wave (RCW) appearance (low energy density conditions). The phenomenon of the RCW represents a reversible process which arose after irradiation of the sample at room temperature by long pulse of IR laser.

Gasdynamic CS2 laser with an aim of increasing the efficiency and expanding the spectral range of lasers of this type

The gasdynamic CS2 laser is investigated theoretically and experimentally. It is theoretically demonstrated that the efficiency of the gasdynamic lasers can be increased by using molecules with lower-lying laser and pumping levels than in the case of C02 or N20 gasdynamic layers. Calculations show that under gasdynamic laser conditions, inversion should set in for an entire series of CS2 molecular transitions in the range 11.4–117 μm. Lasing with wavelength 11.4 μm was obtained in experiment on the (0001)-(1000) transition.

Comparison of CO2 and N2O gasdynamic laser emission energies in systems with mixing

Gasdynamic C02 and N20 lasers are compared in systems with mixing in the near transcritical flow region. It is shown that at T0 > 1300°K the C02-GDL energy is double that of the N20 GDL, but when the lasing temperature is raised the C02 GDL cuts off somewhat earlier than the N20 GDL. It is established that the increase of the lasing energy when an inert gas is added to the mixing GDL of the design investigated by us cannot be attributed to the influence of this inert gas on the kinetics of the vibrational processes.