Resolution of hyperfine structure

With this technique the Doppler width could be reduced by two orders of magnitude below the natural linewidth, and spectral structures within the Doppler width could be resolved. Examples are the resolution of hyperfine structure components in an 12-beam using a single-mode argon laser (tunable within a few gigahertz) or the investigation of the upper state hfs-splitting in the atomic... 

The resolution of hyperfine structure by ENDOR is a well-established method to obtain the structure of the trapping sites of paramagnetic species as shown already in seminal work on single crystals [46]. Information about the local geometry of ions or molecules surrounding the species can also be obtained from powder... 

The technique of Fourier-transform microwave spectroscopy (FTMS) has been applied to the study of a number of weakly bonded complexes, the observation of weak isotopic species, and the resolution of hyperfine structure. It is characterized by higher resolution and sensitivity than conventional Stark-modulated spectroscopy. The superior resolution is demonstrated in Figs. 24 and 25. 

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