We perform part of our work at free electron lasers (FELs), mostly the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory.
FELs are currently the most powerful sources of ultrafast short wavelength pulses covering the spectral range from the vacuum ultraviolet over the soft x-ray range to the hard x-ray domain. Soft x-rays provide element and site sensitivity to electrons within a molecule. Combining this with femtosecond resolution delivers a powerful tool for understanding ultrafast electronic processes in quamtum matter.
Our work uses soft x-ray pulses at the oxygen K-edge (this means the absorption edge due to the 1s electron of oxygen). We typically excite the molecules with UV pulses to start the chemical change of a molecule. We then probe with the soft x-ray pulses to understand the excited state dynamics. The photo shows our apparatus (with the mangetic bottle spectrometer from R. Feifel).