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FTIR under water? Do not reproduce!

How does Bruker’s vacuum research spectrometer deal with water?

What would you understand by “FTIR spectroscopy in water”? Yes, you may think about FTIR ATR or reflection measurements on water-solid or water-air interfaces, or transmission measurements for e.g. protein water solutions in thin liquid cells. The latter experimental setups are typical in biological applications, like protein structural analysis, or kinetic studies of biomolecular folding, binding and catalysis.

In the heart of Europe, the Institute of Biotechnology (IBT), which is part of the Biotechnology and Biomedicine Center of the Czech Academy of Sciences and Charles University in Vestec (BIOCEV) center of excellence, is exactly working on such topics. One of their research programs, “Dynamics of Biological Processes” headed by Dr. Gustavo Fuertes (see webpage), aims to understand light-induced structural, dynamical and functional changes of photosensitive proteins on timescales ranging from femtoseconds to hours. Steady-state and time-resolved FTIR spectroscopy in water is essential to achieve their goals.

The Bruker VERTEX 70v vacuum research spectrometer is used to yield data with temporal resolution down to a few nanoseconds. Such time resolution is the highest available for FTIR technique and can only be achieved using step scan measurement mode. Furthermore, only vacuum spectrometers are able to provide the utmost step scan performance due to their stability and precision in a fully evacuated optical bench.

Water is an ideal solvent for many biological macromolecules, but it is also a very strong IR absorber. Therefore, it is a tricky task to perform FTIR spectroscopy in water with adequate signal intensity. High performance FTIR spectrometers, skilled sample preparation and smart measurement setups, are often required.

The Biophysical facility of the Centre of Molecular Structure (CMS) at BIOCEV includes five FTIR sampling accessories to cover all biomolecular applications. Their setup is particularly useful for the investigation of light-triggered biological phenomena in aqueous solutions or hydrated films.

Unfortunately, one of the spectroscopy laboratories of BIOCEV was accidentally flooded and many sensitive instruments and devices were severely affected. Anyhow, we are proud to report that the Bruker vacuum spectrometer survived this “under water experiment” without severe problems. Only the PC and one electronics card had to be replaced, while the whole optics bench with all optical components inside was well-protected under vacuum. This accidental “experiment” proves the unique quality of Bruker vacuum spectrometers. However, we do neither recommend to repeat it nor do we guarantee that it will always end that positive!