Probing metal-to-ligand charge transfer transitions in ruthenium complexes by quantitative two-photon absorption spectroscopy
Abstract
Degenerate instantaneous two-photon absorption (2PA) cross section and 2PA spectrum measurements were used to determine the molecular electric dipole change in the metal-to-ligand charge-transfer transition of ruthenium(II) triscomplexes of 2,2'-bipyridine and 1,10-phenanthroline ligands. Comparison between the 2PA and one-photon absorption (1PA) spectra indicate that the phenanthroline complex has D3 symmetry in the ground state, while the bipyridine complex has its symmetry lowered. The high accuracy of the nonlinear cross section measurements was achieved by means of improved 2PA reference standards, and the dipole change was evaluated using the two essential states model of 2PA applied in the lowest-energy transitions. We demonstrate that quantitative 2PA spectroscopy is a viable alternative to standard methods used to estimate change of molecular dipole moment, and is uniquely informative of the effects of different solvents and local environments on the absorber.
- Publication:
-
Organic Photonic Materials and Devices XX
- Pub Date:
- February 2018
- DOI:
- 10.1117/12.2290363
- Bibcode:
- 2018SPIE10529E..1DS