The main icOS setup

It is composed of three reflective objectives mounted on a modified MD2 minidiffractometer. It is dedicated to steady-state measurements by UV-Vis abs, fluorescence emission and Raman spectroscopy (excitation at 514, 633 or 785 nm). Continuous time-resolved experiments can be performed in UV-Vis abs and fluorescence emission spectroscopy with a time resolution of 50 to 500 ms.

The online UV-Vis absorption setup

It is available on the CRG beamline BM07, for UV-Vis absorption and fluorescence emission spectroscopy. Continuous time-resolved experiments are possible with a time resolution of 500 ms.

The online Raman setup

It is available on beamline ID30B, next to the icOS Lab, for 785 nm excitation. 

The TR-icOS setup

The time-resolved in crystallo optical spectroscopy (TR-icOS) instrument in the icOS lab is a set-up dedicated to measuring time-resolved UV-Vis absorption spectra on protein crystals on the microsecond to second time scale at room temperature. It utilises a pump-probe scheme, with a tunable nanosecond laser as the pump (possible wavelengths: 355 nm, and between 410 and 2750 nm) and a microsecond xenon flash lamp as the probe to record the transient spectra. A motorised aperture wheel also makes it possible to perform power titration measurements with adjustable pulse energies of 1 µJ - 100 µJ at the sample position.The instrument is optimised for the spectroscopic characterisation of optimal delay times and laser powers before time-resolved diffraction experiments on the microsecond + time-scale (i.e. at ID29) but it is also possible to perform static spectroscopic measurements both aerobically and anaerobically.

Technique: Time-resolved UV-Vis absorption spectroscopy 

Delay times possible: 3 µs - 12 s

Temperature: Room temperature

Crystal size recommended: 10 - 50 µm single crystals (or a slurry of microcrystals)

A few μL of crystal slurry are loaded between 2 layers of COC (100 μm each)/spacer to avoid crystal dehydration during measurements. The magnetic sample holders can also be prepared in advance. It is also possible to measure spectra anaerobically for oxygen-sensitive samples by replacing the COC layers with an oxygen barrier film and preparing the holders in an anaerobic glovebox.