M. P. Dergachov

Dnepropetrovsk National University, Yekaterinoslav, Dnipropetrovs'ka Oblast', Ukraine

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Publications (9)1.12 Total impact

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    ABSTRACT: Spontaneous emission of laser dye molecules (rhodamine 6G and pironin G) em- bedded into pores of synthetic opal photonic crystals is studied in the spectral re- gion of 520-650 nm. It is ascertained that the emission spectra are greatly de- pendent on the photonic stop-band position and the spectral distribution of pho- ton density of states. A dependence of spectral position of the emission band from the dielectric contrast is found. PACS: 78.67-n , 78.55.Mb UDC: 535.361
    Ukrainian Journal of Physical Optics - UKR J PHYS OPT. 01/2010; 11(1).
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    Ukrainian Journal of Physical Optics - UKR J PHYS OPT. 01/2009; 10(4).
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    ABSTRACT: The photonic dispersion, the group-velocity dispersion, the effective mass, refractive index, and the spectral distribution of the density of photonic states near the edge of the photonic stop band are numerically calculated in the one-dimensional model for photonic crystals based on synthetic opals. The fluorescence spectra of rhodamine 6G and 2,5-bis(2-benzoxazolyl)hydroquinone molecules infiltrated into a synthetic opal are measured. For both substances, it is observed that the spontaneous emission intensity in the range of the photonic stop band is appreciably suppressed. A blue shift of the fluorescence spectrum of rhodamine 6G molecules is revealed. Secondary emission of synthetic opals infiltrated with colloidal silver is observed in the Stokes range under excitation of opals by radiation at λ = 400 nm. The spectrum of the secondary emission is located in the range 450–590 nm, which contains the stop band and intervals near its edges.
    Optics and Spectroscopy 11/2008; 105(6):919-923. · 0.56 Impact Factor
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    ABSTRACT: The emission of rhodamine 6G and 2,5-bis(2-benzoxazolyl)hydroquinone molecules embedded in synthetic opal photonic crystals are studied in the spectral range of 520–620 nm. It is found that the intensity of spontaneous emission is suppressed in the spectral region corresponding to the photonic stop band and is amplified on its “blue” side.
    Ukrainian Journal of Physical Optics. 01/2008;
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    Moiseyenko V.N, Dergachov M.P, Burak Ya.V
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    ABSTRACT: Raman spectra of isotopically substituted Li2B4O7 (LB4) crystals have been measured within a wide temperature region (290–1040 K). Temperature dependences of the parameters of vibrational modes with participation of lithium ion have been analyzed. The character of temperature dependences of the frequency and the damping constant of these modes testifies disordering of lithium sublattice and a possibility of order-disorder phase transition in the vicinity of 750 K. Resonant and anharmonic interaction effects have been found to determine spectral intensity distribution in the Raman spectra of LB4 crystals at high temperatures. The possibility of appearance of lithium plasmon vibration in the Raman spectra has been discussed.
    Ukrainian Journal of Physical Optics. 01/2006;
  • V.N. Moiseyenko, M.P. Dergachov, Ya.V. Burak
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    ABSTRACT: The Raman and infrared reflection spectra of Li2B4O7 crystals doped with potassium, silver and copper ions are measured at 300 K. The damping increase of the Raman lines and the changes in the oscillator strengths for a number of reflection bands are observed in the doped crystals. The results obtained due to theoretical fitting of the spectra are discussed in the framework of heavy isotopic impurity model. The analysis of the experimental and theoretical data has allowed to assume that the potassium and silver ions represent substitution impurities, while the copper ions are probably the interstitial ones.
    Ukrainian Journal of Physical Optics. 01/2006;
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    Moiseyenko V.N, Dergachov M.P, Burak Ya.V
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    ABSTRACT: Isofrequency temperature dependences of Rayleigh and hyper-Rayleigh scattering intensities have been measured in isotopically substituted Li2B4O7 crystals within a wide temperature range (300–1000 K). The dependences contain two anomalies in the vicinities of 520 and 800 K. The first anomaly is associated with hopping of lithium ions between two non-equivalent positions, with the activation energy of about 0.23 eV. The second one results from the first-order order-disorder phase transition due to the melting of lithium sublattice. The temperature dependence of the relaxation time obtained by analysing quasi-elastic light scattering spectra is satisfactorily described, using the theoretical relation typical for such the phase transitions, with the relevant parameters Tc = 790 K and D = 0.95.
    Ukrainian Journal of Physical Optics. 01/2005;
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    ABSTRACT: Raman spectra of LiB3O5 and Li2B4O7 crystals have been studied. Raman scattering efficiency and oscillator strengths of some polar vibrations were estimated. Contribution of various vibrations to nonlinear optical coefficients according their assignment has been discussed. Influence of K+ and Ag+ impurity ion on Raman spectra of Li2B4O7 have been studied. Anomalies of the isofrequency temperature dependencies of Raman spectral intensity observed at T equals 235 K are interpreted in terms of the translation structural phase transitions.
    Proc SPIE 02/2000;
  • V. N. Moiseyenko, M. P. Dergachov, V. G. Shvachich
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    ABSTRACT: The emission spectra of nonlinear media with periodical modulation of the second-order susceptibility that are based on synthetic opals infiltrated by Ba(NO3)2, LiIO3, and KH2PO4 are studied using radiation with λ = 400 and 407 nm for excitation. The spectral angular distribution of the emission in the range of 420–650 nm is revealed, as well as the dependence of its spectrum on the photonic stop-band parameters and the exciting radiation characteristics. The emission spectrum of samples with a low dielectric contrast has the shape of a symmetric band with a maximum at 525 nm and a half-width of about 100 nm. The observed emission is interpreted as spontaneous parametric light scattering in a spatially inhomogeneous nonlinear medium.
    Optics and Spectroscopy 112(2). · 0.56 Impact Factor