Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations

Abstract

The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) anin situcalibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-57Fe-enriched [Fe4S4Cl4]=and 10%-57Fe and 90%-54Fe labeled [Fe4S4Cl4]=has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3–4 h to about 30 min. Although the quick-switching calibration is notin situ, it is suitable for normal NRVS measurements.