Browsing by Subject "Dna"

Now showing 1 - 3 of 3

Open Access
Förster-type nonradiative energy transfer for assemblies of arrayed nanostructures: confinement dimension vs stacking dimension
(American Chemical Society, 2014-02-11) Hernandez-Martinez, P. L.; Govorov, A. O.; Demir, Hilmi Volkan
Forster-type nonradiative energy transfer (NRET) provides us with the ability to transfer excitation energy between proximal nanostructures with high efficiency under certain conditions. Nevertheless, the well-known Forster theory was developed for the case of a single donor (e.g., a molecule, a dye) together with single acceptor. There is no complete understanding for the cases when the donors and the acceptors are assembled in nanostructure arrays, though there are special cases previously studied. Thus, a comprehensive theory that models Forster-type NRET for assembled nanostructure arrays is required. Here, we report a theoretical framework of generalized theory for the Forster-type NRET with mixed dimensionality in arrays. These include combinations of arrayed nanostructures made of nanoparticles (NPs) and nanowires (NWs) assemblies in one-dimension (1D), two-dimension (2D), and three-dimension (3D) completing the framework for the transfer rates in all possible combinations of different confinement geometries and assembly architectures, we obtain a unified picture of NRET in assembled nanostructures arrays. We find that the generic NRET distance dependence is modified by arraying the nanostructures. For an acceptor NP the rate distance dependence changes from gamma alpha d(-6) to gamma alpha d(-5) when they are arranged in a ID stack, and to gamma alpha d(-4) when in a 2D array, and to gamma alpha d(-3) when in a 3D array. Likewise, an acceptor NW changes its distance dependence from gamma alpha d(-5) to gamma alpha d(-4) when they are arranged in a 1D array and to gamma alpha d(-3) when in a 2D array. These finding shows that the numbers of dimensions across which nanostructures are stacked is equally critical as the confinement dimension of the nanostructure in determining the NRET kinetics.
Open Access
Generalized theory of förster-type nonradiative energy transfer in nanostructures with mixed dimensionality
(American Chemical Society, 2013-04-16) Hernandez-Martinez, P. L.; Govorov, A. O.; Demir, Hilmi Volkan
Forster-type nonradiative energy transfer (NRET) is widely used, especially utilizing nanostructures in different combinations and configurations. However, the existing well-accepted Forster theory is only for the case of a single particle serving as a donor together with another particle serving as an acceptor. There are also other special cases previously studied; however, there is no complete picture and unified understanding. Therefore, there is a strong need for a complete theory that models Forster-type NRET for the cases of mixed dimensionality including all combinations and configurations. We report a generalized theory for the Forster-type, NRET, which includes the derivation of the effective dielectric function due to the donor in different confinement geometries and the derivation of transfer rates distance dependencies due to the acceptor in different confinement geometries, resulting in a complete picture and understanding of the mixed dimensionality.
Open Access
Highly efficient nonradiative energy transfer mediated light harvesting in water using aqueous CdTe quantum dot antennas
(Optical Society of America, 2010) Mutlugun, E.; Samarskaya, O.; Ozel, T.; Cicek, N.; Gaponik, N.; Eychmuller, A.; Demir, Hilmi Volkan
We present light harvesting of aqueous colloidal quantum dots to nonradiatively transfer their excitonic excitation energy efficiently to dye molecules in water, without requiring ligand exchange. These as-synthesized CdTe quantum dots that are used as donors to serve as light-harvesting antennas are carefully optimized to match the electronic structure of Rhodamine B molecules used as acceptors for light harvesting in aqueous medium. By varying the acceptor to donor concentration ratio, we measure the light harvesting factor, along with substantial lifetime modifications of these water-soluble quantum dots, from 25.3 ns to 7.2 ns as a result of their energy transfer with efficiency levels up to 86%. Such nonradiative energy transfer mediated light harvesting in aqueous medium holds great promise for future quantum dot multiplexed dye biodetection systems. (C) 2010 Optical Society of America.