Origin of the two-component 1437-nm emission structure

Determine whether the two partially overlapping components of the 1437-nm erbium emission in solid neon and solid argon arise from inequivalent trapping sites or from crystal-field splitting of the relevant erbium levels.

Background

The shielded 4f-to-4f transition near 1437 nm exhibits two partially overlapping components in both solid neon and solid argon. Their separation is small, approximately 1 inverse centimeter or less, and their relative weights change with annealing and temperature.

The available spectra cannot distinguish whether the components reflect different local trapping environments or level splitting induced by the crystal field. Similar excitation spectra for the two components provide some support for the crystal-field interpretation, but do not resolve the issue.