Metastable Hydrogen Molecules. II. Fine Structure of Parahydrogen

Abstract

The fine structure of the $N=2$ rotational level of the $(1{\ensuremath{\sigma}}_{g}, 1{\ensuremath{\pi}}_{u})c^{3}\ensuremath{\pi}_{u}$ state of parahydrogen, very probably in the $v=0$ vibrational level, has been measured directly by means of the molecular beam magnetic resonance method. The zero field intervals are: $f(J=2\ensuremath{\leftrightarrow}J=1)=4928.003\ifmmode\pm\else\textpm\fi{}0.010$ Mc/sec, $f(J=3\ensuremath{\leftrightarrow}J=2)=5898.105\ifmmode\pm\else\textpm\fi{}0.012$ Mc/sec. The spin-spin and spin-orbit interaction constants are in agreement with theoretical predictions based on a simplified hydrogenic model.