Charge transfer enhances two-photon absorption in transition metal porphyrins
Jonathan L Humphrey1, Darius Kuciauskas
1Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, Virginia 23284-2006, USA.
Abstract:
Two-photon absorption processes were investigated in electropolymerized Fe(III), Mn(III), and Co(II) 5,10,15,20-tetrakis-(4-hydroxytetraphenyl)porphyrin films. Degenerate four wave mixing (DFWM) spectroscopy with 100 fs pulses in the near-IR spectral region was used. Metalloporphyrins with strong charge transfer (CT) transitions in the linear absorption spectra also show enhanced two-photon absorption. (Metalloporphyrin two-photon absorption cross section, delta, increases >10 times over that for the metal free porphyrin.) This effect was attributed to a two-photon induced charge transfer between the metal ion's d orbitals and the pi-system of the porphyrin. Correlation of one- and two-photon absorption properties of transition metal porphyrins suggests a new and simple approach to improve organic materials for photonic applications.
Related Concept Videos
Ions and Ionic Charges
Photoelectric Effect
Properties of Transition Metals
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
Atomic Fluorescence Spectroscopy
The Electrical Double Layer


