Hamburg 2009 – scientific programme
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MO: Fachverband Molekülphysik
MO 13: Molekülphysik Poster 1
MO 13.25: Poster
Tuesday, March 3, 2009, 16:30–19:00, VMP 8 Foyer
Ultra-broadband single-beam CARS spectroscopy probing CH-vibrations at 3000 cm-1 — •Christina Müller1, Sangam Chatterjee2, Bernhard von Vacano3, and Marcus Motzkus1 — 1FB Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35043 Marburg, Germany — 2FB Physik, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany — 3Polymer Physics, BASF SE, Carl-Bosch-Str. 38, D-67056 Ludwigshafen, Germany
In order to probe a complete coherent anti-Stokes Raman scattering (CARS) spectrum of more than 3000 cm-1 with a single-beam excitation, pulses having an extreme bandwidth are required. In this contribution we demonstrate the extension of the combination of ultra-broadband pulses created in a photonic crystal fibre (PCF) and pulse shaping for non-linear coherently controlled spectroscopy by using two pulse shapers. The first shaper compresses the initial pulse from the laser source to its Fourier limit then acting as pump for the PCF. White light generated within the fibre is characterised and pre-compressed using SHG FROG traces obtained after the beam passed the second pulse shaper. Correction of pulse distortion, especially due to the microscope objectives needed to create CARS frequencies, is accomplished by maximisation single-beam CARS signal using the second shaper again in a closed-loop optimisation scheme. Spectral resolution in any single-beam measurement is as well achieved with the second shaper through sinusoidal phase functions. Pulses as short as 12 fs have been used successfully to probe molecular vibrations corresponding to CH-bonds settled in a range of more than 3000 cm-1.