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Samples of inverted photonic-crystal films, containing planar and rolled-up (in the form of scrolls) CdSe nanocrystals, are studied. The transmission spectra of these structures are recorded. These spectra (along with the change in colour) confirm the incorporation of nanocrystals into the films. The photoluminescence decay dynamics is investigated. It is shown that the photonic-crystal matrix affects significantly the luminescence kinetics of nanostructures. The differences in the decay curves measured for nanocrystals in a photonic-crystal matrix and for their ensemble on a glass substrate are explained by the influence of the photonic-crystal stop band and the orientational effect of crystalline matrix, which orients anisotropic nanocrystals and prevents them from aggregation. The results obtained may be important for potential applications in optoelectronic devices.

The results of the study of the degradation of thermoluminescent materials Li2B4O7:Be + Mn and Li2B4O7:Zn + Mn under the effect of radiation (pulsed electron beam) and laser radiation are presented. As a result of exposure to high doses of radiation, the structure of the samples under study partially acquires an amorphous character, while the effect of radiation exposure is manifested in the optical properties in the appearance of green luminescence due to manganese centers in the tetrahedral environment. With subsequent irradiation with a laser at a wavelength of 350 nm, luminescence centers decay due to photochemical oxidation of manganese by the reaction of Mn2+ → Mn3+. It is shown that Li2B4O7:Be + Mn has a lower radiation resistance than Li2B4O7:Zn + Mn.

Experiments carried out in recent years using single-molecule spectroscopy to study the low-temperature dynamics of some molecular solid-state media with a disordered internal structure made it possible to obtain new information on the dynamics of such media at the local level. In some substances, the time-dependent behavior of the majority of individual spectra of single fluorescent molecules introduced into the studied medium as a local spectral probe corresponded to the predictions of the standard model of tunneling two-level systems. In others, the behavior of most of the spectra of single molecules was more complicated, which it is difficult to describe in the framework of the standard model. This paper is devoted to the analysis of the results of studies of low-temperature spectral dynamics of single fluorescent molecules in a number of disordered molecular systems (amorphous polyisobutylene, toluene, cumene, propylene carbonate). The observed deviations from the predictions of the theory are associated with the microstructure of the systems under study and the sample shape. Possible reasons for the deviations of the observed local spectral dynamics from the predictions of the standard model of tunneling two-level systems are discussed. Inadequately.

Sub-nanosecond luminescence of Mn2+ in Mn-, Sn/Mn-, and Cu/Mn-doped Li2B4O7 ceramics is observed under laser excitation. Picosecond pulsed laser radiation (350–370 nm) generates the frequency-doubled radiation directly in a single microcrystal selected in a ceramic sample, with this secondary radiation falling within the impurity-induced VUV excitation bands of doped Li2B4O7. These excitation bands are attributed to the creation of an impurity-bound intra-anionic exciton in MeiO4–BO3–MnLi complex centres (Mei = Mn, Sn, or Cu). The exciton, in turn, interacts with a nearby Mn2+ ion due to mixing of the Mn2+ excited states with the excitonic states. Exciton annihilation involves Mn2+ energy levels as transient states and causes a sub-nanosecond radiative transition which is accelerated, being accompanied by rearrangement of the surrounding atoms. Excitation within the lower-energy bands is related to the other part of the complex luminescence centre, this is metal-to-ligand intra-anionic charge transfer, which makes an electron accessible to MnLi, while the hole is transferred only during relaxation of the excited structure. Mn2+ radiative transitions are not forced in the latter case, and slow Mn2+ luminescence decay is observed.

A convenient and efficient technique for controlling exact focusing of several noncollinear laser beams into the same point of a luminescent sample is proposed for optical photon-echo spectroscopy and four-wave mixing experiments. The technique proposed is based on a confocal luminescence microscope equipped with a sensitive multichannel detector for visualizing samples with a large magnification. The high efficiency of the scheme developed is confirmed by experimental study of photon echo in a polymer film doped with luminescent dye molecules.

The energy spectrum of low-frequency vibrational modes in amorphous polyisobutylene doped with chromophore tetra-tert-butylterrylene molecules has been measured. The technique for measuring the spectra of vibrational modes in solid amorphous media by single-molecule spectroscopy is described. The measured spectrum is compared with the data on the density of vibrational states (bosonic peak) in pure polyisobutylene, which were obtained by inelastic neutron scattering. It is shown that incorporation of small amounts of tetra-tert-butylterrylene into polyisobutylene did not significantly change the low-temperature vibrational dynamics of the matrix.

The paper summarized the recent results in vibrational dynamics of disordered solids obtained in joint research of Bayreuth University and Institute of Spectroscopy RAS groups via single molecule spectroscopy (SMS). New information about microscopic parameters of the low-frequency vibrational modes (LFMs) in low-temperature glasses was obtained. Studies were based on observations of the line-broadening processes in spectra of single chromophore molecules (SMs) incorporated to disordered matrix as a local spectral probe. Solid organic system, amorphous polymer— polyisobutylene , doped with tetra-tert-butylterrylene molecules, on temperature region 1.6–40 K have been studied. The values of LFM frequencies and SM-LFM coupling constants for the LFMs in the local environment of dopand chromophores were determined. Pronounced distributions of the observed local parameters of LFMs were found. The obtained results demonstrate that SMS is an efficient tool in the study of vibrational dynamics in solid disordered systems on microscopic level.

According to the modern conception, the dynamics of amorphous solids in the intermediate interval of low temperatures (from a few up to dozens of Kelvins) is determined mainly by quasi-localized low-frequency vibrational modes (LFMs). Up to now, it is known very little about a nature and properties of these excitations in disordered solids. High-selective laser spectroscopy of impurity centres, embedded to transparent disordered matrix as a probe, is a very powerful method for deriving information about LFMs. In the two presented papers the results of our photon echo (PE) and single molecule spectroscopy (SMS) studies of LFMs in organic amorphous solids are discussed. In the first part we review the recent results of our PE-studies. Two cases are analyzed: (a) a coupling of chromophores with a continuous broad spectrum of LFMs, which shape was taken from light scattering experiments, and (b) a coupling of chromophores with continuous LFMs spectra, calculated on the base of the soft potentials model. In the second part we consider the results of our studies of LFMs in a glassy polymer on microscopic level using SMS.

The optical dephasing in frozen amorphous toluene doped with octaethylporphine zinc is investigated using the photon echo technique over a wide range of temperatures (0.4–100 K) up to the Debye temperature of solid toluene (T D=100.7 K). The contributions of different mechanisms to the broadening of the zero-phonon line (ZPL) are reliably separated owing to the measurements performed over such a wide range of temperatures. Analysis of the experimental data demonstrates that, at low temperatures, the main contribution to the optical dephasing is determined by the interaction of impurities with fast tunneling transitions in two-level systems. The temperature dependence of the linewidth exhibits a quasi-linear behavior at temperatures below 3–4 K. At higher temperatures, the dominant contribution to the dephasing is made by the interaction of impurities with quasi-local phonons, which leads to a quasi-exponential temperature dependence of the linewidth. It is shown that the latter contribution can be described in the framework of the soft-potential model allowing for a broad spectrum of low-frequency phonon vibrations in the matrix. The temperature of the crossover between the aforementioned two mechanisms of line broadening is determined.

The approach for description of the optical dephasing in doped amorphous solids in the framework of the soft-potential model (SPM) was developed. A procedure for calculation of the homogeneous line width at low temperatures within this model was suggested. The temperature dependencies of the optical dephasing for two amorphous systems, polymethimetacrylate doped with tetra-tert-butylterrylene and zinc-tetraphenylporphine were calculated. Calculations were performed using the parameters known from the literature. The results were compared with the photon echo data for these systems, measured in the broad temperature range. It was found that the SPM describes the temperature behavior of the homogenous line width qualitatively correctly. At temperatures below 2 K, where the main contribution to optical dephasing is associated with tunneling two-level systems, the predicted line width values agree well with the experimental data. At higher temperatures, some difference between the prediction and experimental data was observed and attributed to the effect of impurity on the formation of quasilocal oscillations of the matrix.

We investigated the possible effect of the existence of minimal cutoff distance between two-level system (TLS) and chromophore molecule in glasses on the low-temperature photon echo (PE) and single molecule spectroscopy (SMS) data. Our analysis was based on the tunneling TLS and sudden jump models of glasses. The PE data were considered using the stochastic model of PE in low-temperature glasses as modified by us. Analysis of SMS data was based on the theory of SM line shapes developed by Geva and Skinner [J. Phys. Chem. 101 (1997) 8920]. It was shown that the existence of a minimal approach distance between TLS and chromophore centers results in noticeable changes of the calculated PE and SMS data. These changes increase with increasing of temperature.

We have performed optical photon echo measurements on amorphous toluene doped with zinc-octaethylporphine over a wide temperature interval (0.35–100 K). This broad temperature range, reaching from subkelvins up to the Debye temperature of toluene (100.7 K), enabled a clear separation between the low and high temperature contributions of line broadening processes to the total optical dephasing. The high temperature part of the measured dephasing times was analyzed using recent data from light scattering experiments which determined the spectrum of low-frequency modes of the toluene matrix. The analysis shows that two line-broadening mechanisms contribute mainly to total dephasing: the tunneling transitions of two-level systems, which lead to a power-law temperature dependence of the linewidth at low temperatures (T

A study is made to analyze the possibility of using the soft-potential model in optical investigations of disordered molecular systems with impurities. A procedure is suggested for calculating the temperature dependence of the homogeneous width of a phononless line in amorphous media with impurities within the soft-potential model. A calculation is performed of the temperature dependence of the width of a phononless line (optical dephasing) in an amorphous system of polymethyl methacrylate (PMMA) with an addition of tetratert-butylterrylene (TBT) using the parameters of this system known from the literature. Calculations are performed of the contributions to the width of a phononless line due to the interaction of an impurity with tunneling two-level systems, with thermally activated barrier crossings in double-well potentials, and with quasilocal modes of the matrix. The model calculation results are compared with the experimental data on the photon echo for TBT/PMMA, measured by us in the temperature range from 0.3 to 20 K. It is found that the soft-potential model describes qualitatively correctly the temperature behavior of the homogeneous width of a phononless line. In the temperature range of T < 2 K, where the main contribution to optical dephasing is associated with tunneling two-level systems, the predicted values of phononless line width agree well with the experimental data. At higher temperatures, some difference is observed between the prediction and experimental data, which may be due to the effect of impurity on the formation of quasilocal oscillation of the matrix.

We performed model calculations of the two-pulse photon echo decay (2PE) in amorphous solids at low temperatures in the frame of the theory of Geva and Skinner (J. Chem. Phys. 107 (1997) 7630). The nonexponential shape of the 2PE decay, predicted by this theory, makes the concept of T 2 non-unique. Thus, the measured temperature dependence of the line width depends on the definition of T 2 . This problem was numerically analyzed. 2PE measurements for some amorphous systems have been performed and a strong nonexponential shape of the 2PE decay below 4 K was found.

Optical photon echo measurements on seven doped organic amorphous systems (resoru"n (Res) in D- and D 6 -ethanol (EtOD and EtOD 6 ), tetra-tert-butylterrylene (TBT) in polyisobutylene and in polymethylmetacrylate (PMMA), zinctetraphenylporphine (ZnTPP) in EtOD and EtOD 6 and in PMMA) have been performed in a wide temperature range (0.35}50 K). This wide temperature interval (more than two decades) permits to clearly separate for the "rst time the two di!erent contributions to the line width (optical dephasing): low-temperature broadening which follows a power law, and high-temperature broadening which demonstrates an exponential-like behavior. The values of the exponent a obtained at low temperatures in the cases of TBT and ZnTPP in PMMA matrix show some marked discrepancy with theoretical predictions, which can be attributed to a failure of the standard TLS model for a treatment of these systems or to an inaccuracy of the PMMA parameters calculated in literature. A comparison of the high-temperature part of the line broadening of di!erent dye molecules (ZnTPP and Res), embedded in the same matrices (EtOD and EtOD 6 ) shows that the optical dephasing is determined by two contributions } the dynamics of matrix itself and the dynamics which is related to the doped molecules. ( 2000 Elsevier Science B.V. All rights reserved.

We present the first comparative analysis of spectral data obtained at low temperatures with three different highly selective techniques: two-pulse photon echo (2PE), hole-burning (HB) and single-molecule spectroscopy (SMS) of a polyisobutylene glass (PIB) doped with tetra-tert-butylterrylene (TBT). Our 2PE- and HB-experiments are compared with literature data [Tittel et al., J. Lumin. 64 (1995) 1] obtained by SMS. It is found that the linewidth measured by HB is significantly larger than the mean of the linewidth distribution obtained by SMS. We conclude that a T 2 -dispersion plays an important role in the formation of the linewidth dispersion in TBT/PIB.

Spectroscopic techniques exhibit different sensitivities for line broadening processes in amorphous solids. Photon echo and hole-burning spectroscopy yield averages over the chromophore ensemble. At low temperatures, the results can usually be fitted with a combination of a power-law term — corresponding to the relaxations of two-level systems- and of an exponentially activated contribution of pseudo-local phonon modes. Single-molecule spectroscopy (SMS). in contrast, can resolve the behavior of single dye molecules and yields a distribution of power laws as well as of activation energies. We compare photon echo results for tetra-tert-butylterrylene (TBT) in polyisobutylene (PIB) with SMS data for the same system. The latter were used to simulate numerically the data which would be obtained in an ensemble-averaging experiment. The results of the numerical calculation can be well fitted without assuming a distribution of parameters.

Experimental data on Photon Echoes (PE) in the system terrylene/poly(isobutylene) in the temperature range 0.4–8K are presented and compared with Single Molecule Spectroscopy (SMS) results. From this comparison we conclude that the linewidth distribution in SMS is caused mainly by a large T 2-dispersion (but not slow spectral diffusion). The temperature line broadening is discussed.

The concept of “homogeneous” spectral linewidths in doped amorphous solids and some possibilities to separate the linewidth parts related to the optical dephasing and spectral diffusion (SD) are discussed. The results of the model calculations of the photon echo (PE) decay under conditions of a large dispersion of homogeneous linewidths are presented. The deviations of the PE decay from an exponential due to this dispersion are discussed. The experimental data on incoherent PE in the terrylene/polyethylene system are presented and compared with literature single molecule spectroscopy (SMS) data. It is shown that in this case the dephasing time dispersion plays an important role for the linewidth distribution in SMS. A simple method for separation of the dephasing and SD linewidths in the SMS, based on intensity saturation effects, is considered. The facilities of this method using some SMS data are demonstrated.

On the 17th of January 2002, Roman Ivanovich Personov, one of the founding fathers of site-selective spectroscopy, passed away. The organizers of HBSM’03 asked colleagues of Roman Personov to prepare the present eulogy, which M. Orrit pronounced during the meeting in replacement of Yu.G. Vainer.

Incoherent photon echoes (IPE) decay curve of two differently deuterated ethanol glasses: resorufin in d-ethanol (r/d-e) and resorufin in d 6 -ethanol (r/d 6 -e) have been measured in wide temperature interval (1.7–35 K). At low temperatures the difference in decay times between results of IPE and two-pulse picosecond photon echoes (2PE) were observed and attributed to nanosecond spectral diffusion (SD). The T -dependence of the SD contribution in IPE data was defined and analyzed using Bai-Fayer theory. IPE high temperature results have shown that high-temperature dephasing in r/d-e is caused mainly by interaction with single low frequency mode (LFM). LFM dephasing was analyzed using Osad'ko nonperturbative dynamical theory. The difference in temperature dependencies of dephasing time between r/d-e and r/d 6 -e was observed: the deuteration influenced both on LFM and two-level systems (TLS) contribution to dephasing.

Raman scattering is applied to the study of energy distribution during multiphoton excitation of molecules. The existence of two ensembles-hot and cold molecules-is shown. The fraction of the excited molecules in the upper ensemble is measured for SF(6) and CF(3)I.

Modern techniques allowed measuring the optical spectra of single molecules in transparent hosts. We demonstrate possibilities of Single Molecule Spectroscopy for the study of low-temperature properties of amorphous solids. The overview of the main last results obtained by our group is presented. We are shortly reviewing the newly obtained microscopic information about dynamical processes in low-temperature amorphous solids and about low-energy excitations in these media, such as two-level systems and quasi-localized low-frequency vibrational modes.

The principles of incoherent photon echoes (IPE) are shortly recalled. The results on dynamics in doped organic glasses and polymers (resorufin in d‐ and d6‐ethanol and terrylene in polyethylene) studied by IPE are presented. In all cases the fast dephasing processes are related to coupling with both two‐level systems (TLS) and pseudolocal mode. The nanosecond spectral diffusion (SD) processes has been observed. The IPE‐results are compared with hole‐burning and single molecule spectroscopy (SMS) data.

Until now, in spite of a great number of experimental and theoretical works in study of organic amorphous solids, the basic features of the low temperature dynamics of these mediums are poorly understood. One of the main reason of this is the lack of experimental information about these dynamical processes. In particular, it’s necessary to learn more about optical dephasing in doped organic glasses and polymers for wider temperature interval. It will allow to test the existent theories more correctly and to create new conceptions.

The temperature-dependence of the electronic dephasing for resorufin in d-ethanol glass was measured from 1.7 to 35 K by incoherent photon echo. The difference between two-pulse picosecond photon echo and incoherent photon echo results was obtained and attributed to spectral diffusion in nanosecond time scale.

Roman Ivanovich Personov was born and raised in Moscow. He received a higher education at the Faculty of Physics and Mathematics of the Lenin Moscow State Pedagogical Institute (MSPI), from which he graduated with honors in 1955. After graduating from this institute, he stayed there for postgraduate studies at the Chair of Theoretical Physics. In 1955–1956, Personov served in the Soviet Army, then continuing his post

The temperature dependence of the electronic dephasing of Resorufin in d-ethanol glass was measured from 1.7 to 40 K by incoherent photon echo (IPE) techniques. At T = 8–11 K good agreement between IPE and two-pulse picosecond photon echo (PPE) results was observed. For T 11 K confirm the hypothesis that high-temperature dephasing in this system is due mainly to interaction with a pseudolocal mode.

The resonant Raman scattering spectra of vibrationally highly excited SO2 molecules with the vibrational energy of ∼3.7×104 cm−1 exhibit relatively wide (∼50 cm−1) structurized bands. This spectral width is attributed to the mixing of vibrational levels of the ground electronic state 1A1 due to a non-adiabatic interaction with the vibrational levels of the electronically excited state 1B1.

The method of spectroscopy of spontaneous Raman scattering (RS) with time resolution has been applied for the first time to diagnose the process of multiphoton ir molecular excitation (MPE). Some aspects of RS diagnostics of MPE processes are being analyzed. It has been shown experimentally on SF6 and CF3I molecules that it is possible to study such important characteristics of excitation process as the fraction of molecules involved in the process of excitation, vibrational energy distribution of molecules, stochastization of inner molecular energy.

By the method of double infrared-Raman resonance the stochastization limit E lim in SF 6 and CF 3 I molecules under IR multiple photon excitation is determined: for SF 6 molecules E lim ≲3900±500cm -1 ; for CF 3 I molecules E lim ≲6000 ±500 cm -1 .

High-speed television photon-counting system with digital accumulation was developed for Raman laser spectroscopy.Photosensitive detector consists of three stage image intensifier optically coupled to television tube isocon. The electrostatic gate system of the image intensifier allows to record spectra at the nanosecond time range. The system was used in Raman lidar for remote control of air pollution and in laboratory laser snectrometer for studying Raman spectra molecules SF6 and CF31 excited by CO2 laser. Spectra of various gases recorded by TV system are represented.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.