Study of exchange-coupled pairs of Cr3+ions in Rb3Cr2Cl9

Abstract

The spectrum of Cr3+ pairs in Rb3Cr2Cl9 has been studied using high resolution optical absorption and Zeeman spectroscopy in magnetic fields up to 13 T. In particular, a detailed investigation of transitions from the pair ground manifold (4 A 2×4 A 2) to the singly-excited pair manifold (4 A 2×2 T 1) has been made and the results are discussed in terms of a recent new theoretical approach to the problem of pairs of D3h symmetry. The vibronic spectrum associated with the pair transitions to the (4 A 2×2 T 1) manifold has also been measured and it is shown that it may be explained in terms of strong spinphonon coupling to a small number of A1g modes.