W(100) - With and Without Hydrogen

We have carried out a synchrotron x-ray diffraction study of the pure W(100) reconstruction transition as a function of temperature as well as the room temperature phases and phase transition of W(100) with submonolayer coverages of hydrogen. For clean W(100) we find that below the transition temperature of 250K, the sqrt 2 x sqrt 2 R45degrees diffraction peaks have an intrinsic width, larger than the instrumental resolution, corresponding to finite sized domains.