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DTSTART:20220101T000000
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DTSTART;TZID=Europe/Moscow:20231108T153000
DTEND;TZID=Europe/Moscow:20231108T170000
DTSTAMP:20260905T141249
CREATED:20231031T104028Z
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SUMMARY:Effect of surface charged groups on colloidal\, optical properties and cellular uptake of inorganic nanoparticles
DESCRIPTION:Mikhail Artemyev\nBelarusian State University \n\nEffect of surface charged groups on colloidal\, optical properties and cellular uptake of inorganic nanoparticles \nSurface charged groups play enormous role in colloidal stabilization of inorganic nanoparticles in aqueous solutions. They also govern such important characteristics\, as electrophoretic mobility\, ability to electrostatic interaction with different objects from solid surfaces to biomolecules. Here\, I present our recent results on how to introduce different types of charged groups in the surface shell of semiconductor and metal nanoparticles\, how the sign and the magnitude of the surface charge and the type of groups affect colloidal stability of nanoparticles in aqueous media. Surprisingly\, the surface charge affects not only their electrophoretic mobility\, but indirectly their hydrodynamic size measured by DLS. Both strong negative and positive surface charge is capable to quench the photoluminescence of semiconductor quantum dots and cause a spectral shift of plasmon resonances in silver nanoparticles. Moreover\, various types of cells demonstrate selective uptake of colloidal quantum dots with specific surface charge. All of that demonstrates practical perspectives for utilization of charged plasmonic and semiconductor nanoparticles as the optical nano-sensors and markers. \n  \n  \nAbout Speaker\nGraduated chemistry department of BSU in 1985. Defended Ph.D. in physical chemistry in 1991\, in 2009 defended Dr.Sci. thesis. From 1985 up to now is an employee of RIPCP\, from 2010 head of laboratory of nanochemistry. The main scientific activities lie in the synthesis of colloidal semiconductor and metal nanoparticles\, investigating their optical properties\, photochemical and electrochemical behavior\, interaction with biomolecules and cells. Published more than 200 scientific papers\, IF =45. \n 
URL:https://unam.bilkent.edu.tr/en/event/effect-of-surface-charged-groups-on-colloidal-optical-properties-and-cellular-uptake-of-inorganic-nanoparticles/
CATEGORIES:UNAM Seminars
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DTSTART;TZID=Europe/Moscow:20220615T123000
DTEND;TZID=Europe/Moscow:20220615T133000
DTSTAMP:20260905T141249
CREATED:20220614T062227Z
LAST-MODIFIED:20220614T062629Z
UID:6648-1655296200-1655299800@unam.bilkent.edu.tr
SUMMARY:Probing leaky and guided exciton-polaritons in resonant planar structures
DESCRIPTION:Anton Samusev\nITMO University \n\nPlanar periodic structures such as metasurfaces and photonic crystal slabs strongly coupled to an exciton resonance attract particular attention since they provide vast opportunities for on-demand engineering of the dispersion of guided and leaky polariton resonances. In this regard\, experimental characterization and control of the over modes’ dispersion is of great importance. In this talk\, I will show both what new physical phenomena appear in such systems and how these effects can be directly observed in the experiment. \nIn the first part of the talk\, I will show an experimental approach allowing to retrieve the real [1\, 2] or even full complex [3] dispersion of both leaky and evanescent waves in arbitrary planar structures. The method is based on back focal plane microspectroscopy combined with a solid immersion lens (SIL) separated from the sample by a precisely controlled nanoscale air gap (Otto geometry). Varying the gap allows for extracting both real and imaginary parts of the wavenumber of surface waves propagating in an arbitrary in-plane direction. \nIn the second part of the talk\, I will switch gears to another implication of dispersion engineering in planar structures – the possibility of realization of strong light-matter coupling regime with excitons in transition metal dichalcogenides [4\, 5] and perovskites [6]. I will highlight the nonlinear [4\, 6] and topological [5] properties of exciton polaritons in such systems enabled by finely tuned custom designs of the photonic band structure. \nFinally\, we will discuss how to directly observe and analyze guided exciton-polaritons in planar waveguides either made of a perovskite or based on high-index dielectric slab integrated with transition metal dichalcogenide monolayer. I will show how direct variation of radiative losses via changing the SIL-sample distance in such systems allows for the control of Rabi splitting\, and extraction of exciton-photon coupling strength along with the intrinsic properties of excitons in the sample under study. \nReferences\n1. Pidgayko\, D.\, Sinev\, I.\, Permyakov\, D.\, Sychev\, S.\, Heyroth\, F.\, Rutckaia\, V.\, Schilling J.\, Lavrinenko A.\, Bogdanov A. and Samusev\, A.\, “Direct imaging of isofrequency contours of guided modes in extremely anisotropic all-dielectric metasurface”\, ACS Photonics\, Vol. 6\, No 2\, 510-515\, 2018.\n2. Permyakov\, D. V.\, Sinev\, I. S.\, Sychev\, S. K.\, Gudovskikh\, A. S.\, Bogdanov\, A. A.\, Lavrinenko\, A. V. and Samusev\, A. K.\, “Visualization of isofrequency contours of strongly localized waveguide modes in planar dielectric structures”\, JETP Letters\, vol. 107\, No 1\, 10-14\, 2018.\n3. Permyakov\, D. V.\, Kondratiev\, V. I.\, Pidgayko\, D. A.\, Sinev\, I. S. and Samusev\, A. K.\, “Probing Optical Losses and Dispersion of Fully Guided Waves through Critical Evanescent Coupling”\, JETP Letters\, vol. 113\, No 12\, 780-786\, 2021.\n4. Kravtsov\, V.\, Khestanova\, E.\, Benimetskiy\, F. A.\, Ivanova\, T.\, Samusev\, A. K.\, Sinev\, I. S.\, Pidgayko\, D. A\, Mozharov\, A. M.\, Mukhin\, I. S.\, Lozhkin\, M. S.\, Kapitonov\, Yu. V.\, Brichkin\, A. S.\, Kulakovskii\, V. D.\, Shelykh\, I. A.\, Tartakovskii\, A.I.\, Walker\, P. M.\, Skolnick\, M. S.\, Krizhanovskii \, D. N. and Iorsh\, I. V.\, “Nonlinear polaritons in a monolayer semiconductor coupled to optical bound states in the continuum”\, Light: Science & Applications\, Vol. 9\, No. 1\, 1-8\, 2020.\n5. Li\, M.\, Sinev\, I.\, Benimetskiy\, F.\, Ivanova\, T.\, Khestanova\, E.\, Kiriushechkina\, S.\, Vakulenko\, A.\, Guddala\, S.\, Skolnick\, M.\, Menon\, V. M.\, Krizhanovskii\, D.\, Alù\, A.\, Samusev\, A. and Khanikaev\, A. B.\, “Experimental observation of topological Z2 exciton-polaritons in transition metal dichalcogenide monolayers”\, Nature communications\, Vol. 12\, No 1\, 1-10.\n6. Masharin\, M. A.\, Shahnazaryan\, V. A.\, Benimetsky\, F. A.\, Krizhanovskii\, D. N.\, Shelykh\, I. A.\, Iorsh\, I. V.\, Makarov S.V. and Samusev\, A. K.\, “Polaron-enhanced polariton nonlinearity in lead halide perovskites”\, arXiv preprint arXiv:2201.10265\, 2022 \n  \n  \nAbout The Speaker\nAnton Samusev holds the position of Assistant Professor at School of Physics and Engineering\, ITMO University\, St. Petersburg\, Russia. Since the PhD defense in 2011 at Ioffe Institute\, St. Petersburg\, Russia\, he is leading a scientific group currently comprising 3 Assistant Professors\, 4 Postdocs\, PhD\, MS and BS students. The scientific interests of the group lie at the confluence of the fields of nanooptics\, solid state and laser physics. The research topics include experimental studies of the near- and far-field properties of optically resonant nanoantennas and metasurfaces weakly or strongly coupled to 2D and 3D materials with pronounced excitonic response (transition metal dichalcogenides\, perovskites)\, dispersion engineering of optical surface waves in structured media\, phase change materials\, topological photonics\, photon emission from tunnel junctions\, single-photon emitters and others. Since 2017 Anton lectures the course “Introduction to Experimental Nanophotonics” within the “Nanophotonics and metamaterials” MS program at ITMO University. \nJoin Zoom Meeting\nhttps://zoom.us/j/5876884794?pwd=OUNFRTZKZDNRMm5MWjJjSlhnMXFNUT09https://zoom.us/j/95581724217 \n\n \n 
URL:https://unam.bilkent.edu.tr/en/event/6648/
CATEGORIES:UNAM Seminars
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