We have built a high-energy-resolution monochromator for nuclear resonant scattering from the 9.4 keV nuclear transition of 83Kr. The monochromator consists of two highly asymmetric silicon single crystals arranged in a dispersive geometry and produces an energy bandwidth of 2.3 meV. This monochromator has been successfully used for a study of nuclear forward scattering and nuclear resonant inelastic scattering from a 83Kr sample that was solidified in a diamond anvil cell at 2.15 GPa and room temperature.