Zeeman spectroscopy of Be impurity in GaAs to 30 T

Absorption measurements have been made in fields to 30 T of the far-infrared optical transitions associated with the Be impurity in GaAs. The order and magnitude of the splitting of the ground state has been clarified by low-field (to 6 T) photo-thermal ionisation spectroscopy measurements of the C line. In light of the new high-field data the G line is now believed to comprise two unresolved components. At high magnetic field (above 25 T) a new feature appears which increases in energy with field at a much greater rate than the other transitions; this is thought to originate in valence-band Landau levels