Abstract

We report a remeasurement of the Rydberg constant, to a precision better than one part in 10⁹, via a single photon determination of the Balmer-α wavelength in both hydrogen and deuterium. The new value reflects the redefinition of the meter, a reexamination of corrections and improvements of the experimental apparatus. These changes include a National Bureau of Standards laser (³He-²⁰Ne, ¹²⁷l₂), which is accurate to 1.6 parts in 10¹⁰, an improved dye laser, flatter mirrors, elimination of nonlinearities in pressure scanning, digital recording, a longer etalon (100 cm), and a reexamination of systematic effects and corrections. The result for the Rydberg constant is R = 109 737.315 68(8) cm, where c = 299 792 458 m/s by definition. This result is not in significant disagreement with the preceding measurement by Amin et al.¹ but significantly disagrees with the measurement by Hildum et al.² Another experiment to measure the Balmer-β transition is now under way. We report the progress of this experiment.

© 1986 Optical Society of America