Branching ratios for the decay of n=3 hydrogen atoms in axial and transverse electric fields.

Abstract

The branching ratios for the n=3 to n=2 Balmer-\ensuremath{\alpha} decay of hydrogen atoms in axial and transverse electric fields in the range 0--1000 V/cm have been calculated with use of a density-matrix formalism to take into account the time evolution of the atomic states in the presence of an electric field. The branching ratios are useful when the production of 2s hydrogen atoms is measured with the use of an electric field and when it is desired to correct for cascade contributions from the n=3 level. The total n=3 to n=2 branching ratio is found to depend on each of the 14 independent quantities which determine the axially symmetric n=3 density matrix, thus emphasizing the need to determine the complete density matrix including the off-diagonal coherence terms. If the off-diagonal density-matrix elements are not known, it is preferable to use transverse electric fields since, in this configuration, the contributions to the branching ratios from the off-diagonal terms are less than with axial electric fields. For transverse fields of approximately 200 V/cm, the contribution from the off-diagonal terms are nearly zero.