Equipment

Ultrashort laser pulses are available over a wide range of wavelengths extending from the UV to the mid-IR, through a variety of lasers, nonlinear optical frequency conversion processes, and a state-of-the-art regenerative amplifier system. These short light pulses are used for time-resolved optical spectroscopy, and for nonlinear optical (NLO) spectroscopy. Time-resolved luminescence measurements are performed using a streak camera (Hamamatsu Streakscope) which allows for the parallel detection of the luminescence spectrum as a function of time (~20ps resolution). Even higher time resolution, only limited by the duration of the laser pulses (<80fs from a mode-locked Ti:sapphire laser), is achieved with "pump-probe" measurements. In such measurements, a first pulse excites the sample and a second pulse, delayed by making it traverse a longer distance, is used to probe the light-induced changes in the sample as a function of time. In NLO spectroscopy, such as second-harmonic light scattering (Hyper-Rayleigh scattering), use is made of the extremely high peak-intensities reached in these ultra-short light pulses, leading to new "nonlinear" phenomena not occurring at more usual intensities.

Our Raman scattering spectrometer is an 80cm Dilor XY-800, with triple monochromator allowing for multi-channel liquid nitrogen cooled CCD detection or single-channel PM detection. Four different lasers can be used as light source in a wide range from violet to NIR. This too is a much-used standard research tool with exceptional features.

Visible and near-infrared fluorescence spectroscopy with high sensitivity and throughput

Optimising the excitation source(s), the illumination and collection geometry, and the detectors an instrument for fluorescence measurements in the visible and near-infrared (350-2200 nm) has been developped with very high sensitivity and sample througput.
As a flexible source, a Xe flash-lamp with monochromator is chosen for high intensity illumination at a chosen wavelength, but also various laser sources can be coupled onto the sample.
The excitation and collection assembly is home built with parabolic mirrors for optimal efficiency.
Parallel detection of the spectra is performed with array detectors in the visible (cooled Si CCD detector) and in the near-infrared (cooled InGaAs diode array).