[en] The fluorescence lifetime of Cr sup(3+) in GdA10 sub(3) was measured in the range 1.8 - 4.2 K in magnetic fields up to 6 T. The results show a remarkable dependence of the transition probabilities on magnetic order. A model based on the exchange interaction between Cr sup(3+) in highly excited states and the Gd sup(3+) ions is proposed. (author)

[en] Published in summary form only

No abstract available

No abstract available

[en] Published in summary form only

[en] A new technique for the optical spectroscopy of adsorbed molecules is introduced. It is based on the detection of the phonons emitted during nonradiative relaxation. A high sensitivity was achieved by using superconducting tunnel junctions as detectors. A light power of the order of 1 μW was sufficient for the spectroscopy of submonolayers of tetracene. Molecules deposited on a cold substrate had a spectrum similar to the one of isolated molecules in a solvent. Deposition, or annealing, at room temperature, however, yielded spectra like those of single crystals

[en] In this paper, the electric-dipole transition induced by exchange is used to explain the strong dependence of spin- and parity-forbidden transitions of Cr⁺³ on the sublattice magnetization of an antiferromagnet host. copyright 1997 The American Physical Society

[en] Short communication

No abstract available

No abstract available