Browsing by Subject "Excitation spectrum"

Now showing 1 - 3 of 3

Open Access
Colloidal nanoplatelet/conducting polymer hybrids: excitonic and material properties
(American Chemical Society, 2016) Guzelturk, B.; Menk, F.; Philipps, K.; Kelestemur Y.; Olutas M.; Zentel, R.; Demir, Hilmi Volkan
Here we present the first account of conductive polymer/colloidal nanoplatelet hybrids. For this, we developed DEH-PPV-based polymers with two different anchor groups (sulfide and amine) acting as surfactants for CdSe nanoplatelets, which are atomically flat semiconductor nanocrystals. Hybridization of the polymers with the nanoplatelets in the solution phase was observed to cause strong photoluminescence quenching in both materials. Through steady-state photoluminescence and excitation spectrum measurements, photoluminescence quenching was shown to result from dominant exciton dissociation through charge transfer at the polymer/nanoplatelet interfaces that possess a staggered (i.e., type II) band alignment. Importantly, we found out that sulfide-based anchors enable a stronger emission quenching than amine-based ones, suggesting that the sulfide anchors exhibit more efficient binding to the nanoplatelet surfaces. Also, shorter surfactants were found to be more effective for exciton dissociation as compared to the longer ones. In addition, we show that nanoplatelets are homogeneously distributed in the hybrid films owing to the functional polymers. These nanocomposites can be used as building blocks for hybrid optoelectronic devices, such as solar cells.
Open Access
Experimental conditions for the excitation of thin disk whispering-gallery-mode resonators
(Electromagnetics Academy, 2013) Yurchenko, V. B.; Altintas, A.; Ciydem, M.; Koc, S.
Measurements of mm-wave excitation spectra of highorder whispering gallery modes in free-space cylindrical disk resonators as functions of resonator thickness have been made. Resonators in the form of tight stacks of thin dielectric disks excited via dielectric waveguides have been used in the experiment. Experimental conditions for the excitation of thin-disk resonators have been found. A simple approach for the modeling of resonator spectra and recovery of dielectric parameters has been proposed.
Open Access
Synthesis of symmetrical multichromophoric bodipy dyes and their facile transformation into energy transfer cassettes
(2010) Bozdemir, O. A.; Cakmak, Y.; Sozmen F.; Ozdemir, T.; Siemiarczuk, A.; Akkaya, E. U.
Multichromophoric boron-dipyrromethene (Bodipy) dyes synthesized on phenylene-ethynylene platforms have been be converted to energy transfer cassettes in a one-step chemical transformation. Excitation energy transfer processes in these highly symmetrical derivatives were studied in detail, including time-re-solved fluorescence spectroscopy techniques. Excitation spectra and the emission lifetimes suggest efficient energy transfer between the donor and acceptor chromophore. These novel energy transfer cassettes, while highlighting a short-cut approach to similar energy transfer systems, could be useful as large pseudo-Stokes shift multichromophoric dyes with potential applications in diverse applications.