Optical spectroscopy of individual nanoobjects












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            * Optical spectroscopy of individual nanoobjects
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            Optical spectroscopy of individual nanoobjects (e.g. semiconductor nanocrystals, nanowires

            defects, dopants centers etc.) enables to overcome inhomogeneity in ensembles of such obje
            omnipresent due to impossibility of production of identical objects by the up?to?date nano


            Common measurements on ensembles suffer from the so called inhomogeneous broadening, which
            information on energy levels and transitions in individual nanoobjects. Therefore, startin
            researchers developed various spectroscopic techniques that can indirectly reveal some inf

            by the inhomogeneous broadening, e.g. spectral hole?burning techniques.


            Recent progress of detection devices enabled detecting luminescence spectra directly from 
            nanoobjects. Such techniques are being developed in our laboratory for more than 15 years.
            possible approaches we prefer the luminescence microspectroscopy in a broad optical far?fi

            much less explored than confocal approaches. The reason for such choice is our focus on st
            nanostructures, whose luminescence flux is extremely low due to the indirect band gap ener
            and related long excited?state lifetimes. Thus, our experimental techniques must achieve t

            sensitivity and position stability in order to allow for long acquisition times (typically
            main competitive advantage was gained by successful incorporation of a cryostat in the mic
            set?up – this unique cryo?micro?spectroscopy device is exceptionally stable, giving the ty

            drift below 1 ?m per one hour acquisition at 10 K. Using this set?up we performed several 
            studies, e.g. showing coexistence of quasi?1D and 0D excitons in silicon nanowires, reveal
            phonon lines and phonon?replicas in Si nanocrystals at low T or energy levels of single do

            nanocrystals. Recently we extended our micro?spectroscopy technique into the near?infrared
            region, setting up two parallel detection branches covering a broad range from 350 to 1650
            development consist of incorporation of a time?resolved luminescence detection for both VI

            (the sensitivity is not on the single nanoobject level yet). We apply our micro?spectrosco
            to study other inorganic (Au-nanoclusters and nanorods, SiC, ZnO, MoS2 etc.) and organic m
            organic complexes with lanthanides) and also to measurements in living cell cultures.







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            * Selected outputs
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            • J. Valenta, B. Bruhn, and J. Linnros: Coexistence of quasi-1D and 0D photoluminescence f

              silicon nanowires, Nano Letters 11, 3003-3009 (2011).
            • I. Sychugov, J. Valenta, and J. Linnros: Optical and electrical properties of silicon
              nanocrystals as revealed by single-dot studies (topical review), Nanotechnology 28, 0720

              dx.doi.org/10.1088/1361-6528/aa542b.
            • M. Greben, P. Khoroshyy, I. Sychugov, J. Valenta: Non-exponential decay kinetics: Correc
              description illustrated by slow luminescence of Si nanostructure, Appl. Spectr. Reviews 

              DOI 10.1080/05704928.2018.1517263