On the Effect of Increasing the Radiative-Transition Rate Near a Nanosize Point

A short review of theoretical and experimental studies concerning the photoexcited florescence and Raman scattering of light for a substance in a space containing small material bodies is presented. Calculations of the radiativetransition probability for atoms (molecules) in the vicinity of bodies with a size much smaller than the light wavelength are performed. The probabilities of the singlephoton and doublephoton transitions are shown to increase by factors of 9 and 81 in the vicinity of a nanosize sphere with dielectric constant ||\ 1. The probability of a radiative transition in the vicinity of the vertex of a conic needle bearing up against a plane (both with || 1) increases by factors of (/R _in)² and (/R _in)⁴ for singlephoton and doublephoton transitions, respectively (R _in is the curvature radius for the needle vertex). This theoretical result is suggested as an explanation of the effect of increasing the radiation process intensity in the experiments carried out in the studies cited below.     

Photostability of Molecules of Aromatic Amines in a Polymeric Matrix

In the temperature range T = 5–295 K, the spectralluminescent properties and curves of thermostimulated luminescence (TSL) of molecules of triphenylamine (TPA), trirtolylamine (TTA), triranisolamine (TAA), and N,N'diphenylbis(3methylphenyl)(1,1'biphenyl)4,4'diamine (TPD) in polystyrene and 4Brpolystyrene matrices have been investigated. It has been found that photoirradiation at room temperature in the region of the lowest electron transition of molecules leads to a decrease in the intensities of the luminescence, photoluminescence, and TSL bands, as well as to the formation of new deep traps for charge carriers. At equal irradiation doses these changes in TPD are noticeably less pronounced than in TPA, TTA, and TAA. The higher photochemical stability of TPD molecules compared to TPA, TTA, and TAA is attributed to the difference in the mechanisms of nonradiative deactivation of the triplet states of molecules.     

Monochromatization of synchrotron radiation for nuclear resonant scattering experiments

An introduction to monochromatization of synchrotron radiation in the energy range of 5–30 keV is presented for applications involving nuclear resonant scattering. The relevant relationships of the dynamical theory of Xray diffraction are used to explain basic concepts of monochromatization. These relations are combined with raytracing techniques to design highenergyresolution monochromators. Transmissionoptimized and energyresolutionoptimized designs that achieve high energy resolutions (10⁶)< E/E < 10⁸) are discussed separately. Practical silicon monochromators of both types are presented for a variety of nuclear resonances in this energy range.     

Segregation of Components as a Result of High‐Power Laser Irradiation of Heterogeneous Condensed Media

The effects of periodic segregation of components in metastable (supercooled or supersaturated) binary alloys in the course of kinetic phase transformations as a result of laser irradiation of heterogeneous systems were studied analytically. Nonlinear processes of temporal and spatial selforganization of concentrationrelated structures were simulated using (i) a selfconsistent system of timedependent twodimensional equations for the distribution function for the sizes and spatial coordinates of the newphase particles and (ii) balance equations for the temperature and concentration of dissolved components; the latter equations account for nonlinearity of the particlesource function, sinks, for dependences of the phasetransition temperature on the surface curvature of particles and on the concentration of components, and for diffusive motion of particles in space. The domain of existence for the instabilities under consideration and the characteristics of the formed crystallizationrelated periodic structures are determined. It is established that nanoclusters formed during supersaturation of crystallizing material may play an important role in generation of selfoscillatory crystallization modes. Hydrodynamic aspects of liquidphase concentrationrelated stratification in heterogeneous systems based on immiscible components are considered.     

Heterogeneous Chemiluminescence of Crystal Phosphors on X‐Ray or UV Irradiation

Using a highvacuum assembly with molecular beams and setups with an implemented atom probe, we investigated atomic and molecular adsorption luminescence of the oxides CaOBi and MgO in O and O₂ beams and also radicalrecombination luminescence excited by H and O atoms in ZnS and in ZnS,CdS samples activated with silver, copper, and the rareearth element Tm. It is established that exposure to UV light and xray radiation of the CaOBi, MgO, and ZnSTm samples, where the mechanism of direct excitation of heterogeneous chemiluminescence (HCL) is realized, does not influence the characteristics of the heterogeneous chemiluminescence, whereas similar exposure of the ZnS,CdSCu,Al and ZnS,CdSAg samples and of selfactivated ZnS, in which the excitation of heterogeneous chemiluminescence is due to the ionization of the lattice, leads to an increase in the intensity of heterogeneous chemiluminescence up to five orders of magnitude. The mechanisms of the phenomenon are considered.     

Calculation of the Tautomeric Properties of 3‐Formyl‐Tetrinic Acid by the ab initio and DFT Methods

We have carried out a nonempirical quantumchemical calculation with full optimization of the geometry of all theoretically possible tautomeric forms of 3formyltetrinic acid (FTRA) according to the Møller–Plesset secondorder perturbation theory with the use of a 6–31G(d) double zeta basis set. The correlation corrections to the total energy of molecules for optimized geometric configurations were calculated in the 631G(d,p) basis. All the possible tautomeric forms of FTRA and the harmonic vibrational frequencies were also calculated within the density functional theory (DFT) with the use of the Perdew–Burke–Ernzerhof (PBE) functional in a threeexponent basis. It is shown that FTRA in vapors (in the perfect gas approximation) exists in the form of a mixture of three enol forms, among which two exoforms predominate. The frequencies and forms of normal vibrations for each cisenol tautomer in the region of vibrations of ketogroups and double bonds differ widely, which permits identification of the tautomers present in the mixture. The possible mechanisms of enolenol transformations of 3acyltetrinic acids are discussed.     

Increase in the Gain of a Laser with Autoinjection of Priming Radiation in the Formation of Giant Pulses

Optical schemes of lasers that ensure the formation of giant pulses from narrowband, freeoscillation priming radiation with a change in the Qfactor and simultaneous increase in the gain coefficient and in the coefficient of filling a resonator with an active substance are developed. The results of experimental investigations of the parameters of singlepulse radiation of ruby lasers with electrooptical switching of a linear composite resonator are given.     

On the law of approach to saturation in manganese-magnesium ferrite

The law of approach to saturation is studied for three differently porous samples of polycrystalline sintered Mn-Mg ferrite. Such an internal fieldH is sought that the dependenceI=I _s(1–a/H ²) might be satisfied. The changes which occu rin such a dependence, if the fieldH is changed by a certain multiple of the magnetization, ere investigated by calculation. Relations are derived for this case, which are satisfied very well by the experimental values. The properties of the effective anisotropy constants ara dealt with and, on the basis of temperature measurements, these constants are ascribed with very great probability to the internal form anisotropy.

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- Mn-Mg- . , I= I_S(1-a/H²). , , . , . .

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Reported on in the form of preliminary results in the Institute of Semi-conductors, Academy of Sciences, USSR, in Leningrad on 17. 10. 1960.

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In conclusion the author would like to thank Dr. S. Krupika, C. Sc., K. Závta, C. Sc., grad. phys. R. Gerber and grad. phys. E. Kratochvílová for valuable discussions and A. Hadincová for help in the measurements and for carefully making the numerical calculations and graphs.     

Influence of Solvent Polarity and Viscosity on Nonradiative Processes in Oligothiophenes with Intramolecular Charge Transfer

By the methods of luminescence, picosecond spectroscopy, and quantumchemical calculations the mechanisms of electron excitation energy deactivation in some oligothiophenes with intramolecular charge transfer depending on the solvent polarity and viscosity have been investigated. While for 2Npiperidino5(2,2dicyanovinyl)thiophene (PDCVT) the main channel of nonradiative deactivation is the transition to a lower intermediate state with a twisted double bond controlled by the medium viscosity, in the case of (E){2[25piperidino2thienyl]6(trifluoridemethyl)4H4pyranylidene}propanedinitryl (PTFDN) fluorescence quenching is initiated by the solvent polarity. For two other oligothiophenes, 2Npiperidino5cyanothiophene (PCT) and 2Npiperidino5cyanoterthiophene (PCTT), differing in the length of the thiophene chain, we have revealed, along with the effective quenching of fluorescence in shortchain PCT (independent of the solvent polarity and viscosity), an increase in the radiation capacity in PCTT with increasing polarity of the solvent. The possible mechanisms of nonradiative deactivation in the investigated oligothiophenes are discussed.     

Absorption Spectra of Excited Ruby Crystals

We have investigated the absorption spectra of excited laser single crystals of ruby. The longlived increase in absorption depending on the degree of excitation is observed in optically excited crystals of ruby in a wide spectral range. Moreover, in the absorption spectrum of a postexcited ruby we discovered the excitationinduced longlived kinetic instability, namely, the noiselike quasiline component variable in time and over the spectrum and imposed on the smooth spectral curve.     

Manifestation of Extracoordination in the Resonance Raman Spectra of Water‐Soluble Cation Co‐Porphyrins

Resonance Raman spectra (RRS) of Co(II) and Co(III)5,10,15,20tetrakis(4Nmethylpyridinium)porphyrin ((Co^II(TmpyP4), and Co^III(TMPyP4)) in aqueous solutions at different pH as well as in organic solvents (methanol, ethanol, DMSO, DMF) are obtained. The increased sensitivity of the oscillation frequencies ₂, ₄, ₈, and ₆ — the markers of the oxidation state of a metal — to the nature of an axial ligand has been revealed. For Co^III(TmpyP4), the shifts of the indicated frequencies in extracoordination have turned out to be twofold larger than those for Co^II(TmpyP4). The spectral effects observed are related to different electron influence of the extraligands on the system of the porphyrin ring. In the case of Co(III)porphyrin, interaction of the d orbitals of the metal and the e _g ^*orbitals of the macrocycle is more efficient since its ionic radius is smaller than for the Co(II)complex. For Co^III(TmpyP4), a linear correlation between the oscillation frequencies ₂, ₄, ₈, and ₆ and the experimental Gutmann parameters characterizing the electronacceptor properties of solvents is found.     

Change in the Absorption Spectra of Membranes Containing Co(III)‐ and Sn(IV) Tetraphenyl Porphyrins as a Result of the Use of Anion‐Selective Electrodes Based on Them

Electronic absorption spectra of the components of the membranes of anionselective electrodes containing Co(OH) and Sn(OH) Sn(OH)₂ tetraphenyl porphyrins (TPP) as electroactive substances and various softeners and lipophilic ionic additives have been investigated. 2Nitrophenyloctylic ether, bromonaphthalene, dibutyl phthalate, and dioctyl phthalate were used as softeners; tetradecyl ammonium nitrate and tetrakis(4chlorophenyl)potassium borate were used as ionic additives. To investigate the electronic absorption spectra, we dissolved the membranes in cyclohexane at different pH before and after their use. The influence of the acidity and the nature of a softener on the position and intensity of the absorption bands of metalloporphyrin in a membrane is discussed. It is shown that the use of membranes containing Co(OH)TPP in highly acidic media is accompanied by its demetallation and the formation of protonized forms of TPP. The membranes based on Sn(OH)₂TPP are more stable in acid media.     

Influence of Close‐Range Dipole‐Dipole Interactions on the Real Part of the Susceptibility of a Dense Resonance Medium

Based on a solution of the stationary modified Bloch equations, an investigation is made of the influence of the effect of internal optical bistability (IOB) on the behavior of the refractive index of a dense resonance medium as a function of the constant b of closerange dipoledipole interactions, frequency detuning, and the intensity of optical radiation. The conditions of existence of the IOB effect of the system dense resonance medium + optical radiation are found and the dynamics of the loop width of the hysteresis dependence of the population difference of the resonance levels of the medium on the characteristics of the system is traced. The domains of the parameters are determined in which the effects of selffocusing and selfdefocusing of the radiation propagating in a dense resonance medium can take place.     

Systems Approach to Optimization of the Regimen of Photodynamic Therapy of Solid Sarcoma M-1 Using the “Fotosens” Preparation as Example

A systems analysis of the interaction between objects (tumor, healthy tissue, radiation, and photosensitizer of the singlet state of oxygen) involved in photodynamic therapy was carried out. A schematic diagram of the biologically significative processes proceeding under these circumstances was proposed. This schematic diagram can serve as a basis for a systems approach to the optimization of photodynamic therapy. The efficiency of the systems approach in photodynamic therapy was demonstrated using Fotosens and Khlorin S preparations, carotene, and dodecaprene -carotene in biological experiments on Wistar rats and mouses inoculated for the solid sarcoma M-1.     

Calculation of Out‐of‐Plane Vibrations of a Porphin Molecule

Using the DFT/B3LYP method with the base set 631G^**, we carried out calculation of the frequencies of the normal vibrations of porphin and of its five isotopic types. Scaling of force constants for outofplane vibrations has been performed in independent natural coordinates. The symmetry coordinates are introduced and a force field for outof plane vibrations of a porphin molecule in independent coordinates of symmetry is obtained. A new correlation of the frequencies of vibrations in the type of the symmetry B _1u for the isotopic type of the d ₂ porphin molecule is suggested on the basis of discrete analysis of the distribution of a potential energy.     

Spectral‐Luminescence and Generation Properties of 1‐Aza‐2‐Methyl‐6‐Aminopyrene and of Its Protolytic Forms

Spectral manifestations of protolytic forms of 1aza2methyl6aminopyrene in ethanol and aqueous solutions are investigated. The ionization constants of the protolytic forms are determined. The generation properties and photostability of a neutral molecule and a cation in excitation by an excimer XeCl laser are studied.     

SYNFOS

An expression for the amplitude of a pulse of synchrotron radiation coherently scattered in the forward direction by a Mössbauer absorber consisting of randomly oriented paramagnetic ironcontaining molecules (for example, a frozen solution of a ⁵⁷Fe protein) in an applied magnetic field is derived from the theory of optics. It is assumed that the hyperfine splittings present in the Mössbauer nuclei can be described in the framework of the spinHamiltonian formalism. In the general case of a thick Mössbauer sample of this kind the response on an incident monochromatic and fully polarized beam cannot be given analytically because of the integrations involved. How nuclear forwardscattering for this general case is evaluated in the program package called SYNFOS is outlined.     

Quantum Theory of Self‐Phase Modulation of Ultrashort Light Pulses in a Medium with Inertial Electronic Nonlinearity

We develop a systematic quantum theory of formation of ultrashort light pulses in a squeezed state at selfphase modulation. The response time of the electronic Kerr nonlinearity of the medium is accounted for and the dispersion of linear properties of the medium is described in first approximation. The theory uses the approach based on the momentum operator for the electric field. The response function of the nonlinearity is contained in the interaction operator. The results obtained are valid when the pulse duration is far greater than the nonlinear response time and the carrier pulse frequency is offresonance. It is established that the instantaneous spectral distribution depends quasistatically on the pulse form. In the general case, the spectral distribution of the quadraturesqueezed component is defined by both the response time of the nonlinearity and the magnitude of the nonlinear phase addition. It is also shown that the frequency at which suppression of quantum fluctuations is greatest can be controlled by adjusting the phase of the initial coherent light pulse. It is found that, by registering the quadraturesqueezed pulse using a balanced homodyne detector, the squeezing effect can be efficiently measured if the timedependent phase of the heterodyne pulse obeys a specific dependence defined by the pulse form. The spectral photonnumber distribution of the quadraturesqueezed pulse is studied, and the photon antibunching effect is found for the photon number in a limited spectral band.     

Amplification Coefficient of the Anti‐Stokes Component of Raman Scattering

The theory of intracavity parametric interaction of the components of Raman scattering is developed in the prescribedintensity approximation, which takes into account the reverse reaction of the excited waves to the pumpingwave phase. It is shown that one can substantially improve the conversion efficiency or the amplification coefficient of the antiStokes component by selection of the intracavity geometry, the optimum phase relation between the interacting waves, the pumping level, and the phase mismatch.     

Two‐Wave CO2 Laser with Loss Modulation in Both Channels

The nonlinear dynamics of a twowave CO₂ laser with continuous pumping by an electric discharge and loss modulation in both channels is investigated theoretically. In modulation of losses with the same frequencies it is possible, by changing the shift of the phases of modulating signals, to monitor simply enough the amplitude, form, duration, and depth of modulation and also the repetition rate of radiation. Depending on the shift of phases, the maximum response can be concentrated in the lowfrequency region or propagate also to the region of high frequencies. If losses in both channels are modulated with different frequencies, a change in the relationship between these frequencies predominantly leads to a change in the shape, magnitude, and structure of response in the lowfrequency region of the amplitudefrequency characteristic (AFCh). In the highfrequency region of the amplitudefrequency characteristic, beginning from the peaks of the doubling of the vibration period, where inphase modes of radiation are implemented, the response virtually does not change. Similar regularities are observed on change in the shift of phases.