Related Experiment Video
Updated: May 18, 2026

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Evidence for the Two-State-Two-Mode model in retinal protonated Schiff-bases from pump degenerate four-wave-mixing
Jan Philip Kraack1, Tiago Buckup, Marcus Motzkus
1Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, D-69210 Heidelberg, Germany.
Abstract:
We apply spectrally-resolved pump degenerate four-wave-mixing for the characterization of excited state low-frequency vibrational coherences during the initial events in excited state double-bond isomerization of retinal protonated Schiff-bases. A set of low-frequency coherences in the energetic range of 100-350 cm(-1) appears in the dynamics already for very early delays after initial excitation (<100 fs). The modulations are rapidly damped (<800 fs) and detectable only in a certain time window after initial excitation (<0.6 ps). Following the initial relaxation process, which leads the molecule to a stationary point in the S(1) state, it is not possible to re-excite the coherences in the excited state. Based on our observations, we conclude that the activation of the coherences is only possible to occur in a well-defined region of the excited state potential near the Franck-Condon region. Our results give direct experimental indication for the validity of the "Two-State-Two-Mode model", frequently applied for the interpretation of retinal isomerization dynamics.
More Related Videos
Related Concept Videos
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
¹H NMR of Labile Protons: Deuterium (²H) Substitution
¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...

