Recent advances in high resolution spectroscopy with tunable lasers have made it possible to determine a new value of the Rydberg constant with an almost tenfold improvement in accuracy over recent other experiments. Our research group at Stanford University, i.e. M. H. Nayfeh, S. A. Lee, S. M. Curry, I. S. Shahin, and myself, has recently completed a measurement of the absolute wavelength of the optically resolved 3D5/2 - 2P3/2 component of the red Balmer line Hα of atomic hydrogen and Dα of deuterium.1 Doppler broadening was eliminated by saturation spectroscopy2 with a pulsed tunable dye laser. An iodine stabilized He-Ne laser served as wavelength standard.3 The same measurements provide a new precise value for the Hα – Dα isotope shift. In addition, the splittings between the stronger fine structure components in the optical spectrum were determined to within a few MHz.
KeywordsFundamental Constant High Resolution Spectroscopy Rydberg Constant Marker Resonance Fine Structure Line
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