The objective of the section for optical probe/femtosecond stimulated Raman spectroscopy is to provide a maximally extensive range of pumping and probing options. Both of these can be linked to other experiments, PXS and HHG sources, and can also operate independently. While each element of the optical probe facility is based on relatively established (but still a state-of-the-art) technology, the combination of such a broad range of femtosecond spectroscopic techniques will be truly unique, particularly because all of them might be used on a single sample simultaneously.
The target of the pumping capabilities is to provide users with the option to pump experiments seamlessly with sub-100 fs pulses covering a region from 190 nm up to 15 µm, plus some regions in the terahertz range. All pulses in this range can also be spectrally analyzed for transient changes, such as absorption and stimulated emission, on a shot-to-shot basis. This should allow a broad range of time-resolved experiments to take place including time-resolved protein structures and multidimensional vibrational and electronic spectroscopies. Programmable pulse shapers should also make it possible to perform experiments focused on coherent control and coherent spectroscopies. The concept is based on the highly flexible modular nature of the setup that allows users to perform custom experiments with minimum reconstruction time. Users simply describe what type of pulse sequences (in terms of wavelength, mutual delays, etc.) they want to apply to the sample and what kinds of signals are expected.
In addition to the possibility to inspect extremely fast processes (sub-5 fs), the design should allow arbitrary long delays between pump and probe pulses to be measured. Time-resolved experiments involving processes spanning from a few femtoseconds to a few seconds will be possible to perform within a single session. This option is particularly useful for studying biological samples, which are very organized on multiple levels.