Feasibility tests of transmission x-ray photoelectron emission microscopy of wet samples

We performed feasibility tests of photoelectron emission spectromicroscopy of wet samples in the water window (285-532 eV) soft x-ray spectral region. Water was successfully confined in an ultrahigh vacuum compatible compartm ent with x-ray transparent sides. This water cell was placed in the MEPHIST O spectromicroscope in a transmission geometry, and complete x-ray absorpti on spectra of the water window region were acquired. We also show micrograp hs of test samples, mounted outside of the compartment, and imaged through the water. This technique can be used to study liquid chemistry and, at lea st to the micron level, the microstructure of wet samples. Possibilities in clude cells in water or buffer, proteins in solution, oils of tribological interest, liquid crystals, and other samples not presently accessible to th e powerful x-ray photoelectron emission spectromicroscopy technique. (C) 20 00 American Institute of Physics. [S0034-6748(00)04501-9].