Facultatea de Fizică şi Inginerie / Faculty of Physics and Engineering

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    Self-absorption of violet radiation in ZnO thin films produced on ZnSe crystal surfaces by isovalent substitution method [Articol]
    (Elsevier, 2018) Goglidze, T.I.; Dementiev, I.V.; Covali, A.V.; Goncearenco, E.P.; Nedeoglo, Natalia; Nedeoglo, Dmitrii
    Photoluminescence (PL) spectra of ZnO thin films produced by isovalent substitution method by means of thermal treatment of zinc selenide single crystal substrates in air are studied in 350 – 750 nm range at room temperature. Irrespective of annealing temperature (500 – 870 °C) and annealing time (20 – 120 min), PL spectra consist of a short-wavelength violet radiation with maximum localized between 396 and 423 nm and a long-wavelength yellow-orange radiation with maximum localized between 575 and 600 nm. Both PL bands are attributed to donor-acceptor (DA) pairs. It is shown that the violet PL band intensity decreases and the yellow-orange PL band intensity increases with increasing ZnO film thickness that is caused by self-absorption of the short-wavelength radiation and energy transmission to DA-pair centres of the long-wavelength radiation.
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    Determinarea stadiului de vegetație, a calității și tipului solului prin măsurări ale spectrelor optice [Articol]
    (CEP USM, 2020) Spincean, Veaceslav; Caraman, Mihail; Chirița, Arcadii; Paladi, Florentin
    Sunt cercetate spectrele de reflexie difuză și de fotoluminescență pentru probe de sol și de frunze colectate la diferite stadii de dezvoltare. Stadiul de vegetație a frunzelor și tipul lor poate fi determinat atât după marginea benzii de reflexie difuză în intervalul 460÷520 nm, cât și după valoarea numerică a coeficientului de reflexie difuză în regiunea pantei dependenței Rd(λ).Este determinat intervalul spectral în care se poate stabili calitatea și tipul solului după mărimea coeficientului de reflexie difuză.
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    Crystalline structure and photoluminescence of GaSe-CdSe nanocomposite [Articol]
    (2015) Dmitroglo, Liliana; Evtodiev, Igor; Caraman, Iuliana; Kantser, Valeriu; Untila, Dumitru; Stamate, Marius; Gasin, Petru
    A material consisting of CdSe and GaSe crystallites with average dimensions of 34 nm and 30 nm respectively was obtained by heat treatment at 753K and 853K of GaSe single crystal plates in Cd vapors during 24 hours. As a result of Cd atoms interaction with Se atoms CdSe layers are formed both onto outer surface and at interface of layered Se-Ga-Ga-Se packages. CdSe crystallites on the surface grow in the form of plates along C6 crystallographic axis. Photoluminescence spectra of the composite, at 78K and 300K, contain predominant bands from the luminescent emission of GaSe and CdSe components.
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    Photoluminescence of n-ZnSe single crystals doped with iodine by vapour phase diffusion [Articol]
    (2006) Avdonin, A.N.; Nedeoglo, Dmitrii; Nedeoglo, Natalia; Sirkeli, Vadim; Ivanova, G.N.
    Photoluminescence spectra of n-ZnSe single crystals doped with iodine are investigated in the temperature range from 83 to 300 K. It is shown that the edge PL band is formed by overlapping of the PL lines attributed to ISe donor-bound ecxitons (I2I) and VZn acceptorbound excitons (D1I). A model of radiation mechanisms, which explain the redistribution of the edge and long-wave PL bands intensities with increasing doping level of the samples, is proposed.