Hannover 2020 – wissenschaftliches Programm
Die DPG-Frühjahrstagung in Hannover musste abgesagt werden! Lesen Sie mehr ...
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MO: Fachverband Molekülphysik
MO 9: Femtosecond Spectroscopy I
MO 9.6: Vortrag
Mittwoch, 11. März 2020, 12:15–12:30, f102
Structural Changes in Metal-To-Ligand Charge Transfer States Investigated by Time-Resolved Vibrational Spectroscopy — •F. Hainer1, N. Alagna1, E. Domenichini2, M. Darari3, P. Gros3, S. Haacke2, and T. Buckup1 — 1Institute of Physical Chemistry, Ruprecht-Karls University Heidelberg, Germany — 2University of Strasbourg, CNRS, IPCMS, Strasbourg, France — 3University of Lorraine, CNRS, L2CM, Nancy, France
Iron(II) complexes with nitrogen-heterocyclic carbene (NHC) ligands are about to become promising chromophores for solar energy applications. In spite of the great interest in these compounds, the assignment of the electronic states involved in the excited state relaxation dynamics is still an open question. In this work, we employed femtosecond transient absorption as well as (pump-)impulsive vibrational spectroscopy to investigate the electronic and vibrational dynamics in the relaxation pathway of such an iron(II)NHC complex. Three contributions are identified and the vibrational dynamics in the low-frequency region is discussed. The photoexcitation of an 1MLCT state is followed by ultrafast intersystem crossing (ISC), which is accompanied by an intermolecular vibrational redistribution of 100cm−1 mode. The vibrational modes appearing below 100cm−1 and at 150cm−1 correspond to metal-ligand stretch vibrations and are assigned to the electronic excited state manifold. A deformation vibration of the ligand backbone at 350cm−1 is found to survive the ISC, indicating that the charge remains on the ligand. The results point to a ground state recovery from a 3MLCT without a 3MC state taking part in the dynamics.