Abstract
The dielectric function of was measured for the a and b axes in the photon energy range 0.8–4.5 eV at room temperature. By varying the Ca concentration we control the relative abundancy of and We observe that the intensity of the main optical absorption peak at 1 eV is proportional to the number of ions. This rules out the interpretation as a excitation, and it establishes that this is the on-rung bonding-antibonding transition.
- Received 31 May 2000
DOI:https://doi.org/10.1103/PhysRevB.62.16522
©2000 American Physical Society