K.R. Hoffman

Does Er@C60 emit light?

We present the results of recent investigations into the production, isolation and optical characterization of erbium metallofullerenes. Near-infrared emission from Er 3+ has been previously observed from Er 2 @C 82 . However, Er 2 @C 82 cannot be responsible for all of the observed emission near 1.5 μm. This paper describes recent attempts to determine the source of this additional Er 3 + emission from metallofullerenes. Our work focuses on using sublimation techniques in order to separate the numerous metallofullerene molecules created in the reaction process. Based on these studies we tentatively assign the observed emission to Er@C 60 .

Circular dichroism and Raman optical activity in antiferromagnetic transition-metal fluorides

The Raman optical activity (ROA) of magnons in rutile-structure antiferromagnetic FeF2 (TN=78 K) is studied as a function of temperature and applied magnetic field. For exciting light incident along the c axis, ROA is observed for magnons but not for phonons. In zero field, a small splitting (0.09 cm−1) of the two acoustic-magnon branches is observed for the first time by inelastic light scattering. The splitting in applied magnetic field is found to reduce with increasing temperature in accordance with theory. No ROA is detected for two-magnon excitations. In optical absorption measurements performed over thirty years ago, a very small circular dichroism (CD) was observed in the magnon sidebands of other simple rutile antiferromagnetic fluorides (MnF2 and CoF2). The origin of this CD was not understood at the time. The Raman studies of the one-magnon Raman scattering in FeF2 have demonstrated that in zero field the degeneracy of the antiferromagnetic magnon branches is lifted by a weak magnetic dipole-di...