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Title: Spectroscopy of a narrow cooling transition in Holmium
We report on accurate measurements of the hyperfine constants of the narrow cooling transition of neutral Holmium at 412.1 nm. This transition has a linewidth of 2.3 MHz and a Doppler temperature of 55 microK which renders it suitable for second stage laser cooling. The proximity of the wavelength to the strong cooling transition at 410.5 nm[1] renders this transition convenient for first and second stage cooling using a combined optical setup. The hyperfine constants were measured using Doppler free saturated absorption spectroscopy in a hollow cathode discharge. Relative measurements of the locations of the hyperfine levels were made using an EOM modulator with an RF offset relative to a stable ULE cavity reference. The A and B hyperfine constants were determined to be A= 715.85±0.15 MHz and B= 1013±16.0 MHz which significantly improves on the precision of earlier measurements.  more » « less
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Bulletin of the American Physical Society
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National Science Foundation
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