For 10 points, name this form of spectroscopy that relies on the recoil-free emission or absorption of gamma rays by a sample, based on an effect named for a German.
Klingelhoffer miniaturized the apparatus used in this technique in the MINOS apparatus, and one effect measured in this experiment is the splitting of spin states by a quadropole moment, which is used to characterize spin states.Â  Other quantities calculated include the magnetic splitting and the isomer shift, which can be used to measure covalency and electronegativity.Â  The apparatus is typically kept cold by liquid nitrogen, and is typically calibrated using the electron capture of Cobalt-57 to Iron-57, which gives a line at 14.4 kev.Â  The sample and source are moved relative to each other by a linear track, and the absorption of the sample is measured at various velocities. Â For 10 points, name this form of spectroscopy that relies on the recoil-free emission or absorption of gamma rays by a sample, based on an effect named for a German. 
Klingelhoffer miniaturized the apparatus used in this technique in the MINOS apparatus, and one effect measured in this experiment is the splitting of spin states by a quadropole moment, which is used to characterize spin states.
Mossbauer spectroscopy 