A liquid flow cell to study the electronic structure of liquids with soft X-rays

We describe the design of a temperature-controlled flow-through liquid cell dedicated to the study of liquids with soft X-rays. The cell can be operated with internal ambient pressure and is mounted on a standard vacuum manipulator, making it compatible to the ultra-high vacuum environment required in synchrotron beamlines. The liquid is separated from the vacuum by a thin membrane, allowing the use of soft X-ray photon-in–photon-out techniques such as X-ray emission and fluorescence-yield X-ray absorption spectroscopy to study the electronic structure of liquids and liquid–solid interfaces. Special care was taken for a rapid and effective flow of the liquid inside the cell in order to minimize local heating and beam damage effects. To illustrate the capabilities, oxygen K X-ray emission spectra of D2O and H2O are presented and briefly discussed together with possible problems that may arise from X-ray-induced oxide formation at the membrane–liquid interface.