Laser-induced fluorescence spectroscopy in the near ultraviolet has allowed detailed investigations relating to jet-cooled free radicals that are of importance for the understanding of combustion and atmospheric processes.

Each of three basic coherent transient phenomena (optical nutation, free polarization decay photon echo) can be generated by sufficiently abrupt modulation of the interaction between the matter and radiation. This can be performed by rapid commutation of either radiation parameters, or the parameters of the matter. I present here comparative analysis of these two approaches (the first one, using electro-optical switching of the resonant laser power to create the pulses for the gas excitation and the second one, based on the Stark switching of vibro-rotational levels in a gas, excited by CW laser radiation), used in our experiments in molecular gases, from the point of view of both their capability to generate various coherent transients and their sensitivity to the intensity of laser radiation.

Investigation of the photoinduced processes in pure C₆₀ films and in C₆₀ films doped by Ti or Sn was performed by means of sub-100 fs resolution spectrometer. Excitation by 100 fs laser pulses with photon energy above and below the mobility edge revealed that both charged and neutral components appear during the excitation pulse. At both excitation wavelengths electrons and holes are generated by direct optical excitation and not due to singlet-singlet annihilation. Anions are created with a delay of 10^-13 - 10^-11 s in a result of electrons capture by C₆₀ molecules. Compared to the pure fullerene this process is faster for Sn-doped and slower for Ti-doped sample. Oxygen uptake in the film is mainly responsible for the observed characteristic features of the relaxation in Ti-doped C₆₀. For Sn-doped C₆₀ the yield of charge carriers photogeneration is noticeably larger than for pure C₆₀. Non-monotonic relaxation, observed in the former case, is explained by the charge exchange between C₆₀ anion and metal.

The low temperature (20 K) electronic absorption and emission spectra of terrylene (C₃₀H₁₆) and perylene (C₂₀H₁₂) isolated in Kr matrix are presented. The spectra of both chromophores reveal similar multiplet structure, and in each spectrum, six different sites were identified. In order to understand the origin of observed site-splitting, the theoretical calculations of complex system -- chromophore embedded into Kr matrix -- were carried out by means of MM+ method. The optimization of system structure yielded six different types (sites) of embedding chromophore molecules into Kr crystal lattice. As calculations have shown, the nearest environment of each embedding type distinguishes by its specific density of Kr atoms packing, on which basis the relationship between theoretically calculated sites and observed spectral features was established.

We present low temperature absorption and fluorescence spectra of terrylene and its derivative di-tert-butylterrylene (DTBT) in the series of n-alkanes -- from n-octane to n-dodecane. Calculations by means of MM+ and INDO/S methods were carried out with the aim to establish how the guest molecules of the chromophore are embedded into the host crystalline lattice of n-alkanes, special attention being paid to the n- nonane matrix.

Laboratory device and operate principle of optical echo- spectrometer ensuring viewing of a quantum transition branch type by means of looking for a photon echo (PE) shape under the fluent realignment of resonant radiating frequency within research oscillatory -- fluctuate band of the molecular gas (vapors of molecular iodine) are discussed.

The light scattering from a nano-sized object formed by two or three dipole atoms (polarizable components) is studied in detail using a microscopic approach. The atoms are considered to be linear Lorenz oscillators interacting via the electromagnetic field only. For simple configuration of nano- object, the self-consistent electromagnetic problem is solved analytically. It is shown that the near-field interaction between the dipole atoms can give rise to a dramatic modification of the polarizing characteristics of atoms and the total polarizability of nano-object. We point out the existence of a number of resonance peaks in the frequency dependences. The shift of resonance peaks from the position of the resonances corresponding to the isolated atoms depends mainly on the interatomic distances and can significantly exceed the natural linewidth. Generally, the resonance characteristics of atoms depend on various system parameters such as the atomic polarizabilities (i.e. the eigen- frequencies), the number of atoms, and the interatomic distances. The scattered light intensity detected in wave zone is shown to depend essentially on the configuration of nano- object, the light frequency, polarization, and direction of external wave.

Infrared absorption spectra and internal rotation of 1,2-di- (p-XC₆H₄)ethanes (X equals Br, NO₂) have been investigated. The magnitude of the barrier to internal rotation of 1,2-di-(p-bromophenyl)ethane has been estimated. The analysis of IR spectra of 1,2-di-(p-nitrophenyl)ethane in liquid and crystalline states and its solutions has allowed to make conclusion about the presence of the dynamic equilibrium of the trans and gauche conformations. The division of the absorption bands into components and the factor analysis have been used in the interpretation of the IR spectra. The enthalpy and entropy differences of the trans and gauche conformations have been determined and besides these values are discovered to be anomalous large as compared with ones which are usually observed for the conformational equilibria.

A nonrelativistic theory of non-local light-matter interaction is developed. Wave functions and energies of spherically symmetric bound states of hydrogen atom with self-consistent field are calculated. The obtained results are compared with the classical results of quantum mechanics.

This paper describes regularized wavelets and numerical algorithms for a regularized wavelet-analysis based on the Bayes strategy. This program includes the investigation of a possibility for finding a basis in terms of a multiresolution analysis under condition that a scaling function would satisfy the properties of a regularization operator and an orthonormal basis simultaneously. Examples of application of the regularized wavelets in the differentiation of composite simulated spectra with a fractal noise are considered.

In the paper one of possible reasons for explanation of strange transport in the turbulent plasma in the presence of a fluctuating magnetic field is discussed. A model of self- similar fluctuations in the magnetic field is investigated in terms of the microscopic theory based on a kinetic diffusion equation for plasmas. A problem of non-Markovian evolution for fluctuations in a magnetic field is discussed and the appearance of anomalous transport is illustrated. It is shown this particular class is of special interest for the description of subdiffusive process.

Optocapacity spectroscopy method is offered. This method based on the characteristic of semiconductors to change conduction at the influence of optical radiation. Conduction changing is registered through capacity change between metallic plates, to which fits an under investigation sample. The method is noncontact and allows to research samples of semiconductors, which thickness less, than diffusion length of free carriers of charge.

Free polarization decay and photon echo were detected as heterodyne signals in the weak component of radiation, polarized at right angle to the principal part of exciting radiation. Coherent responses were generated in 13CH3F gas by Stark switching of molecular levels in a gas excited by CW CO2 laser radiation at 9P (32) line. The specific features of this technique in comparison with the conventional Stark switching method of coherent transients generation is considered.

Multiple photon echo signals were found to be the reflection of the oscillation structure of the primary echo signals formed by excitation of two-level active centers. Amplitude pulses are of the same length, but their amplitude is different. The length of the pulse is comparable with the delay between them. The primary photon echo of the oscillation structure is shown to exist in the intervals (-t₁,t₁) and (-2t₁,2t₁). It was established that under certain correlation between the amplitudes of exciting pulses the oscillation signal structure becomes asymmetric. That is why in the regime of square-law detection of the primary photon echo signal its asymmetry oscillation structure is observed in the form of frequent of isolated signals (multiple photon echo), the distance between them being equal to the pulse length.

The experiments on primary and backward photon-echo (PE) in extended crystals of ruby are presented.

It is studied the mechanism of an impurity optical frequencies shift by the heat ballistic phonons in ruby. The photon echo is used as phonon detector. The optical frequencies shift is the same for the distinctive ion groups. It is the basic result of given work:

One qubit is mapped to two level system in the standard model of quantum computation: a typical example is a spin-1/2 system. Further progress requires the use of network of multilevel quantum systems of different physical origin in solids: optical levels, large or strong interacting spins etc. We propose virtual qubit formalism and show how the quantum objects state space can be used as a basis for multiqubit information recording and processing in a quantum computer. It is suggested to map the qubits into solid state NMR spin system collective states instead of the state of the individual spin. Such an approach introduces the stable computational basis without any additional actions and allows to obtain the universal set of quantum gates, which operation time is determined only by the RF pulses.

Some problems of the optical data processing, based on long- lived photon echo, are analyzed theoretically.

The excitation of stimulated echo by two pulses of Gaussian white noise, which are originated from a single source and short coherent pulse is considered. The present work studies the nonlinear properties of average amplitude of the echo as function of the spectral power density. The mean value of the complex envelope of the echo is obtained by solving stochastic Bloch equations in Stratonovich sense. The results can be used for analysis of nonlinear excitation characteristics based on saturation effect in photon and spin processors.

Mode of photon echo (PE) exciting is theoretically considered, when in quality the pulse-code is used a set of pulses with the different time and polarizing characteristics. It is offered to consider a combination of polarizing and peak-time characteristics of a PE signal in algebra of quaternion. A principle of information processing with quaternion representation of signals is experimentally realized.

Fiber-optic head is developed and fabricated for information reading out from and writing-down to hard carriers. Fiber- optic scanner using this head is realized on the basis of existing computer printers and plotters and its characteristics are investigated. Fiber-optic technique is used for excitation of photon echo. Photon echo was observed with multimode fiber when it was coupled with initial pulsed laser radiation in quasi-singlemode regime. Predictions are made for the possibility of creation photon-echo fiber-based echo-processors and their possible schemes are proposed.

Possibilities of the using of a photon echo (PE) phenomena at the creation of informational-measuring systems of the speed control of an internal ballistic motion of a gas, of a visual control branch types of quantum transition of the molecular gas by a peak-temporary shape of a photon echo, and of distance measurement are discussed. The influence of lunar cycle phases to the process of formation of an echo-response is shown on an example of research of an echo-dielectric permeability, registered in a water physiological solution of chloride natrium.

The principle of operate and structured scheme of optical high-tension measurement current transformer on photon echo are considered in work. It is described about checking of branch type of working quantum transition. It is discussed about a motivation of ranges of current measurement and a way of accuracy improving of measurement.

Possibilities of photon echo technique in sensing of atmosphere are explored. As example the vapor of molecular iodine is considered as the promising resonant medium for the photon echo lidar (PE-lidar). The two schemes of PE-lidar are discussed and the ways of their optimal use for the atmosphere sensing are analyzed.

A kinetic equation making use the Fokker-Planck approximation describing a single-mode micromaser field generation in case of a multiparticle correlated atomic ensemble is derived. As example, N particle atoms states produced by a cloning and telecloning are considered and noise of the micromaser generation is founded.

It is shown numerically that a thin layer of semiconductor quantum dots has a threshold transmission characteristic for the ultrashort incident pulse. Weak pulses mainly reflect from layer while pulses with amplitudes above the threshold mainly transmit. The coherent interaction of optical pulses with the layer of quantum dots causes the forming of peaks of superradiation on the profile of transmitted pulses. The phenomenon is accompanied by rapid temporal evolution of ellipticity and azimuth angle across the pulse duration.

The arrangement of experiments on stopping of light pulses is generalized on the non-collinear falling of initial waves. Kinetic equations describing the recording and retrieving of information are derived in the framework of nonequilibrium statistical operator method. Their holographic solution is obtained. It shows that the direction of retrieved wave is defined by phase synchronism condition appropriate to dynamic holography in general. With that, the information is stored in such quantum holography on Einstein-Podolsky-Rosen pairs of atomic transitions thus providing extremely dense recording of information with possibility of its quantum processing after recording and subsequent non-demolition read out of computed result.

In the frames of quantum electrodynamics, the behavior of spontaneous decay is investigated for a single two-level atom embedded into a microscopic object (cluster). The transition frequency of cluster atoms is supposed to be considerably detuned from the transition frequency of decaying atom. The consideration is performed on the base of fully microscopic quantum-electrodynamical approach with simultaneous solution of Heisenberg equations for atomic and quantum field operators. The special attention is paid to the investigation of renormalization of spontaneous emission rate due to proper account of discrete structure of medium. The formula for decay rate is obtained without using the notion of refractive index. It is obtained that spontaneous decay strongly depends on the geometrical arrangement of atoms in microstructure. For some form of clusters, decay rate is found to be considerably large compared to its vacuum value that is not the case for macroscopically large dielectrics.

The method of elimination of boson operators is used to theoretically analyze the possibility and optimal conditions of superradiance regime of laser cooling of crystals and glasses doped with rare-earth ions. A set of kinetic equations governing the processes of laser cooling and optical superradiance in a multilevel system is derived for the pulsed regime. It is demonstrated that the efficiency of laser cooling in this regime is proportional to a factor N²(lambda) ²Kn_S, where N is the number of active impurity centers, (lambda) is the superradiance wavelength, K is the number of superradiance channels, and n_S is the number of superradiance events per second.

On the basis of the master equation for the density matrix the dynamics of the three-level atom interacting with two mode of quantum electromagnetic field in the damped cavity has been considered. The behavior of the mean populations of the atomic levels and photon numbers in modes has been investigated.

Theoretical model is constructed for solid state lasers with internal refrigeration effect. Kinetic equations are derived in the framework of nonequilibrium statistical operator method for self-cooling and radiation balanced lasers. Predictions are made for the ways of their practical implementation.

We investigate effects of nonlocality in time of interaction of an atom with its surroundings on the spectral line broadening. By using an exactly solvable model, we show that these effects can be very significant: In some cases nonlocality in time of interaction of an atom with its surroundings can give rise to the spectral line splitting.

We investigate the effects of nonlocality in time of interaction on the dynamics of open quantum systems. We show that the generalized quantum dynamics allows one to take into account nonlocality in time of the interaction of an atom with its surroundings in describing spectral line broadening.

Kinetic equation governing the evolution of phase difference for the radiation in correlated laser is derived using nonequilibrium statistical operator method. It is converted into an equivalent Fokker-Planck equation for the P- representation. The solutions of last equation show that spontaneous radiation doesn't pose the Schawlow-Townes quantum limit on gravitational wave detection in active interferometer based on correlated laser with coherent beating provided that the width of locking zone connected with correlation effect is larger than the laser radiation natural width.

The real and imaginary part of the linear ac susceptibility and real nonlinear (cubic) ac susceptibility is investigated in terms of quantum spin glass droplet model. The temperature dependence and frequency one is calculated by analytical and numerical methods on the basis of the linear and nonlinear dynamical response theory in quantum mechanical systems. Slow quasi-equilibrium dynamics and divergence of the nonlinear ac susceptibility is found. Numerical calculations of frequency dependence illustrate the crossover between high and low frequency behaviors. It is supposed the existence of glass- like type transition at non-zero temperature while at zero temperature the results coincide with previous one.

The problem of describing optical turbulent structures, arising in resonant media with high Fresnel numbers, is reviewed. The consideration is based on the probabilistic approach to pattern selection, ascribing a probability distribution of patterns to systems with multiple possible structures. The most probable structure corresponds to the minimal expansion exponent, or to the minimal expansion rate, characterizing the phase-space expansion of a dynamical system. Turbulent photon filamentation is studied. The most probable filament radius and the number of filaments are found, being in good agreement with experiment.

Second harmonic generation was considered with regard to dispersion of nonlinear susceptibility, and second- and third- order dispersion of the group-velocities. The case of a finite phase mismatch is analyzed and analytically. The steady state pulses of the fundamental and second harmonic waves were found. Modulation instability of the continuous wave solution is considered. The correction terms for MI thresholds, which are resulted from dispersion of non-linear susceptibility, were found.

Self-induced transparency under two-photon and Raman resonances is studied theoretically in the cases of small angular momentum of resonant transition and essentially different intensity of resonant waves. The last corresponds to the condition of experiment of Grabtchikov et al [Phys.Rev.Lett.81,5808 (1998)]. The problem with account to wave polarization was reduced to generalized Maxwell-Bloch equations which are exactly integrable by the inverse scattering transform method.

The soliton formation is considered which is feasible in quasi-resonant media of multilevel atoms modeled by the generalized two-level systems, taking account of the dynamic Stark effect. A soliton solution of the extended Maxwell-Bloch equations system is found, bistability properties thereof being predicted.

Transient phenomena such as free polarization decay and photon echo in dense resonant media taking into account short-range dipole-dipole interaction of atoms are investigated.

The theoretical investigation of acoustic self-induced transparency for longitudinal-transversal acoustic pulses at their propagation in system of resonant paramagnetic impurities with effective spin S equals 1/2 and S equals 1, along to external magnetic field (Faradey geometry) is carried out. Among the obtained solutions is present essentially new result. On the basic of analysis of this solutions the conclusion is made that the presence of the longitudinal component leads to modulation of the transversal component carrying frequency.

We present a new, to our knowledge, method of Stokes-anti- Stokes Raman amplification in fiber, based on our idea of anti-Stokes generation at stimulated Raman scattering in media with variations of third order nonlinearity ((chi) ⁽³)) along longitudinal coordinate. By numerical simulation the quasi-phase matching conditions at different pump wave intensity are obtained. The dependence of layers lengths on pump wave intensity is computed. We received the models of media in which the Stokes-anti-Stokes amplification coefficient is higher than 10 dB.

The stability of polarization, areas and number of self- induced transparency (SIT)-solitons on an output the LaF₃: Pr3⁺ sample is theoretically researched versus of the polarization direction and the area of the input linearly polarized laser pulse. For this purpose the Vector Area Theorem is rederived taking into account directions of the dipole matrix element vectors of the six different subgroups of Pr3⁺ ions. It is shown that there are SIT solitons, which polarizations are directed so between as along the crystallographic axes in the LaF₃:Pr3⁺. For an absorbing medium the interference of these ion's subgroups reduces that SIT-solitons are stable if its polarization is directed between the crystallographic axes. Solitons are nonstable, if its polarization are directed along one of the crystallographic axes: a small change of an input pulse polarization reduces to a soliton splitting up into two separate solitons, which polarizations are directed between the crystallographic axes under an angle +30 and accordingly -30 degrees to the given axis. For an amplifying medium it is just on the contrary.

Equations of coherent stimulated Raman scattering (SRS) are analytically solved in the prescribed pump field approximation. The intensity of Stokes and anti-Stokes waves for different spatial mismatching is determined. Efficiency of anti-Stokes generation is found to be maximal for its definite value. The expression for angular size of anti-Stokes ring depending on the length of sample, the laser pulse energy and other parameters of the problem is obtained.

A model of superradiant scattering of light from a Bose- Einstein condensate based on a semi-classical approach is proposed. Choosing coherent states with definite momentum as a basis of atomic states we derive a Maxwell-Bloch equations for the system considered and obtain their solutions that describe the temporal evolution of intensity of scattering light and population of the coherent atomic states.

The results of theoretical and experimental investigations of optical superradiance in a pyrene doped biphenyl crystal in a cavity are presented. The set of equations of motion for the collective population difference, photon number and medium polarization are solved for two time intervals corresponding to superradiance kinetics in a cavity.

The multipulse regime of excitation of optical superradiance in both two- and multilevel systems is theoretically investigated. It is demonstrated that this regime is the generalization of the triggering regime of superradiance excitation. The possibilities of information processing and laser cooling of solids under this superradiant regime are discussed.

A four-level model, involving the ground, one-exciton and two- exciton states as well as a high-lying molecular term through which the two-exciton state annihilates, is used for analyzing the bistable optical response of an ultrathin film built up of oriented molecular aggregates. We focus on the effects of inhomogeneous broadening of the exciton optical transitions and exciton-exciton annihilation on bistability of the film response. It turns out that the inhomogeneous broadening, preventing generally the occurrence of bistability, may be suppressed considerably due to a fast exciton-exciton annihilation.

The generation of reflected and transmitted waves in induced superradiance is investigated. It is demonstrated that the exponential increase in the amplitude of the total field at the linear stage of the process may be accompanied by a periodic coherent exchange between the forward and backward waves in a sample. Transition to the nonlinear stage in a certain phase of this exchange determines the predominance of the transmitted or reflected wave in the pulse. The influence of the area of the initiating pulse and the sample length is considered.

Under analysis is the influence of the local field upon the competition of transitions in the process of superradiance from incompletely excited thin layer of three level atoms ((Lambda) -diagram of the operating transitions). It is highlighted that while the upper sublevel of the lower doublet starts degenerating, there is a superradiant regime, where the combinative transition leads the development of the superradiance pulse, and the time of the pulse delay depends on the parameters of the local field and splitting of the lower doublet.

We investigate possible regimes of one -- or two -- color mode superradiance of femtosecond optical pulses and accompanying parametric generation of infrared pulses, which contain a few periods of field oscillations, in quantum-well heterolasers of micrometer length under cw pumping. The effects of strong magnetic field and inhomogeneous broadening of electronic levels of dimensional quantization in quantum wells are analyzed.

A new scheme for generation of coherent radiation on the intersubband transition without population inversion between subbands is presented. The scheme is based on the resonant nonlinear mixing of the optical laser fields on the two interband transitions that are generated in the same active region and serve as a coherent drive for the infrared field. The two-wavelength lasing on the interband transitions can be achieved at substantially lower threshold current than population inversion and gain on the intersubband transition. This may ensure stable high-power room-temperature operation. Due to parametric, inversionless nature of generation, the proposed lasers are especially promising for the long- wavelength operation above 20 micron.

The structure of the radiation field inside periodical multilayer including resonant ⁵⁷Fe layers, as a function of the angle (in vicinity of the Bragg peak), energy or time, has been analyzed for the cases of the energy-resolved or pulsed excitation by synchrotron radiation. It has been shown that the variations of the angle of incidence in vicinity of the Bragg angle allow to scan across the bilayer depth and to get from reflectivity spectra itself the depth selective information on the magnetic ordering in an interface region.

We considered the scattering of Mossbauer radiation by nuclei in soft ferromagnets whose magnetization reverses periodically under the influence of external radio-frequency magnetic field. In the framework of the step-wise reversals model we analyzed a few effects such as splitting of Mossbauer lines, short enhancement of coherent radiative channel and suppression of incoherent (reaction) those following the reversals of the magnetic field at the nuclei. Basic optical equations are presented as well.

The possible variants of amplification of gamma radiation without inversion is analyzed for the six level model nuclear system I_g equals 3/2 and I_e equals 1/2 which can be influenced by the bichromatic radiofrequency (RF) field. The variant of amplification without inversion has been found with no bichromatic radiofrequency (RF) field. If it is still necessary then the amplitudes of the particular monochromatic components should be no equal.

Nuclear forward scattering (NFS) of synchrotron radiation (SR) is being modeled in metal proteins containing the single paramagnetic centers of integer spin (Fe²⁺). It is known the spin fluctuations in the electron environment of Moessbauer ion Fe²⁺ will be manifested itself in NFS if a sample undergoes the influence of applied magnetic field of a few Tesla. Under the condition we are analyzing how the resonant response (RR) of a sample to SR pulse will be changed due to the both spin-lattice and spin-spin interactions.

A process of stimulated Mandelshtam-Brillouin (MB) light scattering was investigated in solutions with critical point of stratification and singular point. Temperature dependence of a behavior of the electrostriction coefficient was determined. Some changes in its value in the vicinity of critical points were revealed. Observed changes are different and depend on a nature of the critical point.

The nucleation and growth of local molten regions (LMRs) during the light irradiation was detected using high-speed camera and long-focus microscope. In situ dependences of sizes and density (quantity per cm^-2) of LMRs are interpreted in the frame of the following model. A great amount of heat is transferred to the semiconductor surface during light pulse irradiation. This proces is nonstationary and the heat is not distributed homogeneously over the thickness of the sample. As a result, a specific short-lived state is formed, in which the semiconductor surface is superheated in the solid-state phase with respect to the equilibrium melting temperature. Some surface areas, which contain the defects, begin to melt. Temperature of these local molten regions immediately decreases down to the equilibrium melting temperature. The created LMRs begin to absorb the heat from neighboring superheated solid regions. As a result, the temperature of superheated regions decreases down to the equilibrium melting point. No new local molten regions are formed and the sizes of existing local molten regions increase due to absorption of the energy of light pulse. To study the main features of local melting more detail in-situ investigations of mechanism of this effect were carried out at incoherent light irradiation with different pulse durations and irradiation power densities. The last our results agree with the superheating model. Also the dynamics of phase transitions on the surface of implanted silicon at different regimes of light pulses is investigated using high-speed camera and special diffraction gratings. The diffraction gratings were formed using ion implantation and the effect of local melting. The dynamics of diffraction during and after the light pulse irradiation was studied.

The theory of interference of light based on a principle of a superposition of waves does not cover completely experimental data. The alternative concept of interference based on the assumption of interaction of light beams by way of exception from the law of their independence is considered. Is shown that within the frame of this concept it is possible to reach the best agreement between the theory and experimental data.

The supposition about a presence of the secondary emission of a screen edge under the action of the falling radiation in the diffraction phenomenon in optics is put forward. The treatment of a diffraction of light for rectilinear edge of the opaque screen and on a narrow slot is given within the framework of such supposition.