A Common-Path Interferometer for Time-Resolved and Shot-Noise-Limited Detection of Single Nanoparticles

We give a detailed description of a novel method for time-resolved experiments on single non-luminescent nanoparticles. The method is based on the combination of pump-probe spectroscopy and a common-path interferometer. In our interferometer, probe and reference arms are separated in time and polarization by a birefringent crystal. The interferometer, fully described by an analytical model, allows us to separately detect the real and imaginary contributions to the signal. We demonstrate the possibilities of the setup by time-resolved detection of single gold nanoparticles as small as 10 nm in diameter, and of acoustic oscillations of particles larger than 40 nm in diameter

Heilpädagogische Diagnostik. Zur wissenschaftlichen Stigmatisierung von Kindern und Jugendlichen, die an den Folgen von sexualisierter Gewalt litten

Der Beitrag beschäftigt sich mit struktureller, epistemischer und sexualisierter Gewalt an Kindern und Jugendlichen, die von der Jugendwohlfahrt in Österreich betreut wurden. Viele dieser Jugendlichen besuchten zugleich eine einrichtungsinterne Schule, in der sich die Gewalt fortsetzte, ebenso wurden viele bereits im Zuge der flächendeckenden Schuleingangsuntersuchungen mit Gewalt konfrontiert. Die vorliegenden Ergebnisse gehen zurück auf Forschungen im österreichischen Bundesland Kärnten. Da die Hauptakteure österreichweit agierten, sind die Ergebnisse des Forschungsprojektes – trotz seines Ausgangspunktes in Kärnten – nicht regional beschränkt. (DIPF/Orig.

Enhancing the optical excitation efficiency of a single self-assembled quantum dot with a plasmonic nanoantenna

We demonstrate how the controlled positioning of a plasmonic nanoparticle modifies the photoluminescence of a single epitaxial GaAs quantum dot. The antenna particle leads to an increase of the luminescence intensity by about a factor of eight. Spectrally and temporally resolved photoluminescence measurements prove an increase of the quantum dot's excitation rate. The combination of stable epitaxial quantum emitters and plasmonic nanostructures promises to be highly beneficial for nanoscience and quantum optics.Comment: 5 pages, 4 figure

Ultrafast spectroscopy of single molecules

We present a single-molecule study on femtosecond dynamics in multichromophoric systems, combining fs pump-probe, emission-spectra and fluorescence-lifetime analysis. At the single molecule level a wide range of exciton delocalisation lengths and energy redistribution times is revealed. Next, two color pump-probe experiments are presented as a step to addressing ultrafast energy transfer in individual complexes

Cascaded four-wave mixing in tapered plasmonic nanoantenna

We study theoretically the cascaded four-wave mixing (FWM) in broadband tapered plasmonic nanoantennas and demonstrate a 300-fold increase in nonlinear frequency conversion detected in the main lobe of the nanoantenna far-field pattern. This is achieved by tuning the elements of the nanoantenna to resonate frequencies involved into the FWM interaction. Our findings have a potentially broad application in ultrafast nonlinear spectroscopy, sensing, on-chip optical frequency conversion, nonlinear optical metamaterials and photon sources