Crystals were located in a 1.25 mm wide gap between the central and the outer conductor where field strength was maximum. The salt solution reservoirs in each coil end of the capillary were located outside the slab-line, hence were not exposed to MMW.
High microwavepower levels mainly led to increased, but largely recoverable, lattice defects owing to the evaporation of crystal water. At lower microwavepower levels, the presence of the microwave field resulted in localized reproducible changes in the mean-square displacements (B factors). The average B factor was found to increase with microwavepower, consistent with an increase in temperature. However, the B factors of the atoms in a few highly localized sites in the protein showed reproducuble changes upon microwaveexposure that are not explained by heating.