Zeeman Effects in Transient Spectral Hole-Burning of the R1 Line of NaMgAl(Oxalate)3·9H2O/Cr(III) in Low Magnetic Fields

Abstract

Transient spectral hole-burning experiments, using diode lasers, in minute external magnetic fields of <16 mT are reported for the lower-energy 2E ← 4A2 spin-flip transition of NaMgAl(oxalate)3·9H2O/Cr(III). Ground- and excited-state g factors can be accurately determined by an analysis of multiple side holes observed in the selective hole-burning experiments of the R1(±3/2) and R1(±1/2) transitions with B||c and B⊥c. The observed g factors, (R1) = 1.38 ± 0.04, (R1) = 2.00 ± 0.08, and (R1) = 1.82 ± 0.08, imply a large variation from trigonal behavior that is caused by a low-symmetry component of the ligand field. The zero-field hole widths in a 0.5% crystal are ∼19 ± 5 MHz and 23 ± 5 MHz for holes at the low-energy edge of the R1(±1/2) line and the high-energy edge of the R1(±3/2) transitions, respectively. Upon application of a magnetic field of B||c = 7 mT, a substantial narrowing of the hole width is observed for the R1(±1/2) transition, with an upper limit for the homogeneous line width of ∼1 MHz. The present work illustrates the potential of diode lasers in the determination of the magnetic properties of transition-metal complexes by transient spectral hole-burning experiments in low magnetic fields.