Scanning microscope for high speed pump-probe ASOPS – spectroscopy of single metallic nanostructures

O. RISTOW; M. HETTICH; A. BRUCHHAUSEN; T. DEKORSY

Bad Honnef, Germany

Workshop; Wilhelm- und Eles Heraeus Seminar on “Quantum Optics of Nano- and Micromechanical Systems”; 2009

Physikzentrum Bad Honnef (Germany)

We present the implementation and the first results of a scanning stage microscope coupledto a high-speed asynchronous optical sampling (ASOPS) pump-probe experiment [1]. Thismethod is based on two asynchronously linked femtosecond unidirectional ring lasers of1 GHz repetition rate, one providing the pump pulse while the other provides the probepulse. The time delay between both pulses is realized by introducing a fixed off-set of 10 kHzin the repetition rates of the two lasers.The absence of mechanical moving parts, as used in conventional pump-probe experiments,allows for very fast scanning rates and an unprecedented signal to noise ratio [2].We have coupled this set-up to a microscope, achieving a focal spot size of approximately1.3 μm. Furthermore using a CCD camera and a motorized scanning stage we are able toselect and resolve single nanostructures as well as to scan larger samples with high spatialresolution.We show preliminary results of pump-probe experiments investigating the dynamics of goldnano-pyramids grown on glass and silicon substrates, and we demonstrate the potential of thissystem for the investigation of time-resolved vibrational properties of single metallic nanostructures.