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Institute: search.filters.UBSInstitut.Stuttgart Research Centre of Photonic Engineering (SCoPE)Institute: search.filters.UBSInstitut.4. Physikalisches InstitutEnd date: 2019Author: search.filters.author.Weiss, Thomas

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Now showing 1 - 3 of 3
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    ItemOpen Access
    Short-range surface plasmonics: localized electron emission dynamics from a 60-nm spot on an atomically flat single-crystalline gold surface
    (2017) Frank, Bettina; Kahl, Philip; Podbiel, Daniel; Spektor, Grisha; Orenstein, Meir; Fu, Liwei; Weiss, Thomas; Horn-von Hoegen, Michael; Davis, Timothy J.; Meyer zu Heringdorf, Frank-Joachim; Giessen, Harald
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    ItemOpen Access
    Surface- and tip-enhanced resonant Raman scattering from CdSe nanocrystals
    (2015) Sheremet, Evgeniya; Milekhin, Alexander G.; Rodriguez, Raul D.; Weiss, Thomas; Nesterov, Maxim; Rodyakina, Ekaterina E.; Gordan, Ovidiu D.; Sveshnikova, Larisa L.; Duda, Tatyana A.; Gridchin, Victor A.; Dzhagan, Volodymyr M.; Hietschold, Michael; Zahn, Dietrich R. T.
    Surface- and tip-enhanced resonant Raman scattering (resonant SERS and TERS) by optical phonons in a monolayer of CdSe quantum dots (QDs) is demonstrated. The SERS enhancement was achieved by employing plasmonically active substrates consisting of gold arrays with varying nanocluster diameters prepared by electron-beam lithography. The magnitude of the SERS enhancement depends on the localized surface plasmon resonance (LSPR) energy, which is determined by the structural parameters. The LSPR positions as a function of nanocluster diameter were experimentally determined from spectroscopic micro-ellipsometry, and compared to numerical simulations showing good qualitative agreement. The monolayer of CdSe QDs was deposited by the Langmuir–Blodgett-based technique on the SERS substrates. By tuning the excitation energy close to the band gap of the CdSe QDs and to the LSPR energy, resonant SERS by longitudinal optical (LO) phonons of CdSe QDs was realized. A SERS enhancement factor of 2 × 10 3 was achieved. This allowed the detection of higher order LO modes of CdSe QDs, evidencing the high crystalline quality of QDs. The dependence of LO phonon mode intensity on the size of Au nanoclusters reveals a resonant character, suggesting that the electromagnetic mechanism of the SERS enhancement is dominant. Finally, the resonant TERS spectrum from CdSe QDs was obtained using electrochemically etched gold tips providing an enhancement on the order of 10 4 . This is an important step towards the detection of the phonon spectrum from a single QD.
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    ItemOpen Access
    Modeling of second-harmonic generation in periodic nanostructures by the Fourier modal method with matched coordinates
    (2018) Defrance, Josselin; Schäferling, Martin; Weiss, Thomas
    We present an advanced formulation of the Fourier modal method for analyzing the second-harmonic generation in multilayers of periodic arrays of nanostructures. In our method, we solve Maxwell’s equations in a curvilinear coordinate system, in which the interfaces are defined by surfaces of constant coordinates. Thus, we can apply the correct Fourier factorization rules as well as adaptive spatial resolution to nanostructures with complex cross sections. We extend here the factorization rules to the second-harmonic susceptibility tensor expressed in the curvilinear coordinates. The combination of adaptive curvilinear coordinates and factorization rules allows for efficient calculation of the second-harmonic intensity, as demonstrated for one- and two-dimensional periodic nanostructures.