Pakutavad lõputöö teemad

Synthesis of red phosphors with pre-defined emission wavelength based on Mn4+-doped hexafluorides

Juhendaja: A. Vanetsev

Microwave-hydrothermal and/or metathesis synthesis of Mn4+-doped nanoparticles of M12M2F6 or M1M2F6, where M1 – Na, Ca, Rb, Ag or Ca, Sr, Zn, Mn2+, Ba and M2 – Si, Ge, Sn, Ti, Zr for white LED applications. Potentially Mn4+-doped phases are one of the best candidates for white LED applications as red-emitting phosphors, but there is a string of problems starting from phase and morphology control and to optimal position of absorption and emission bands in spectra.

Synthesis of multifunctional d- and f-metal doped carbon dots

Juhendaja: A. Vanetsev

This is a new, fast growing topic. Carbon dots are very flexible in terms of composition and they possess very interesting optical and magnetic properties. The idea is to dope them with luminescent or magnetic ions to enhance/modify properties.

Reactions between nanoparticles and ALD layer as a path for new materials

Juhendajad: A. Vanetsev, A. Tamm

Study of the reactions between nanoparticles and ALD thin films on their surface. ALD (atomic layer deposition) is a technique, which allows to grow thin films of a material over surfaces of any type and complexity. Usually, functionality of a substrate and functionality of a film are considered separately, but we aim to study the chemical interactions between ALD layer and substrate nanoparticles in order to obtain materials with otherwise unachievable properties (e.g., magnetic or fluorescent).

Plasma-induced processing of nanomaterials in liquids

Juhendaja: A. Treshchalov

The synthesis of surfactant-free nanomaterials (graphene, metal nanoparticles) is a challenging task for nanotechnology and applications as components in electrical devices, catalysts, biochemical sensing. A compact reactor is suggested and developed for plasma treatment of water solutions. When a plasma jet interacts with a liquid surface a lot of short-lived chemically active species (radicals, electrons, positive and negative ions) penetrate into the water and activate electrochemical reactions while water acts as a heat sink and heat can be quickly dissipated. The aim of the work is to study: 1) The pathways of nucleation and growth of metal (Ag, Pt) nanoparticles; 2) Mechanisms of reduction of graphene oxide as well as the nature of the electrostatic stabilization of these nanomaterials by in situ monitoring the UV–VIS absorption of the water solution during the plasma treatment.

Conical refraction in biaxial crystals and its use for laser beam shaping

Juhendaja: V. Peet

Using He-Ne laser, the effect of conical refraction in biaxial KGW crystals will be studied. Main features of the effect as Hamilton-Lloyd ring, Poggendorff dark ring, and axial spikes will be measured and analyzed. The polarization pattern of conically refracted light and the formation of some special types of laser beams as Bessel and Laguerre-Gauss ones will be studied.

Solvothermal and microwave-hydrothermal synthesis of near-infrared emitting nanocrystals of rare-earth fluorides

Juhendajad: A.S. Vanetsev, Yu.V. Orlovskiy

Nanoparticles emitting in the near infrared (NIR) region fit very well for bioimaging and visualization tasks in medicine, particularly for cancer tumors, as human body is most transparent in the NIR region. The main problem of these materials is fluorescence quenching. We are developing a synthetic approach, which will allow maximizing the fluorescence brightness of these materials through a control of phase composition, crystallinity and morphology of nanoparticles. However, the high brightness is not the only the goal of the study. By analyzing the fluorescence decay in time (fluorescence kinetics) we are detecting the crystal structure defects unavailable for detection by other methods.

 

Kõrge lahutusvõimega fluorestsentsmikroskoopia

Juhendaja: V. Palm

Kõrge valgustundlikkusega CCD kaameraga varustatud konfokaalmikroskoop võimaldab uurida nt plasmoonseid mikrostruktuure ja nende interaktsiooni fluorestseeruvate molekulidega. Sobivate objektide puhul on võimalik saavutada tundlikkust üksikute molekulide tasemel. Bakalaureuse töö on suurel määral seotud aparatuurse osa omandamisega. Sellest võib välja kasvada ka magistritöö teema.

Teemandi luminestsentsitsentrite rakendamine optiliste temperatuurisensoritena

Juhendajad: L. Puust, I. Sildos

Teemat täidab üliõpilane Caius Miller

Bioloogiliste kudede optiliseks vaatluseks tuleb kasutada lähi-infrapunast kiirgust ( ca 750–950 nm), millele kude on enam-vähem läbipaistev. Osutub, et teatud lisanditega teemanti kristallid neelavad ja kiirgavad just selles diapasoonis ja oletatavasti ka säilitavad oma kiirgamisvõime nanokristallis, kui viimane asetada bioloogilisse vesikeskkonda. Enamus  elutegevusest toimub toatemperatuuri ümbruses. Teemandi lisandikiirguse mõned karakteristikud  on küllalt tundlikud temperatuuri muutustele selles temperatuuripiirkonnas. Töö eesmärgiks ongi uurida lisandatud teematide optilisi spektreid ja nende rakendamist bioloogilistes kudedes mikroskoopiliste optiliste temperatuurisensoritena.