Related Experiment Video
Updated: Jul 30, 2025
07:11
ARL Spectral Fitting as an Application to Augment Spectral Data via Franck-Condon Lineshape Analysis and Color Analysis
Published on: August 19, 2021
2.5K
Vibrations That Do Not Promote Vibronic Coupling Can Dominate Observed Lineshapes in Two-Dimensional Electronic
1Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India.
The Journal of Physical Chemistry Letters
|May 12, 2023
Summary
Impulsively generated wavepackets reveal distinct origins of coherence map lineshapes in bacteriochlorophylls and photosynthetic reaction centers. This clarifies their spectroscopic significance for understanding ultrafast electronic relaxation and designing functional vibronic couplings.
Area of Science:
- Ultrafast spectroscopy
- Photochemistry
- Quantum dynamics
Background:
- Impulsively generated wavepackets probe vibronic couplings governing electronic relaxation.
- Coherence maps (CMs) in multidimensional spectroscopy visualize wavepacket dynamics.
- Understanding CMs is crucial for deciphering mechanisms and designing functional molecular systems.
Purpose of the Study:
- To distinguish the origins of similar diagonal node-like coherence map lineshapes.
- To connect spectroscopic observations with underlying microscopic processes in electronic relaxation.
Main Methods:
- Multidimensional spectroscopy
- Analysis of coherence maps (CMs)
- Theoretical modeling of wavepacket dynamics and electronic relaxation pathways
Main Results:
- Distinct origins identified for CM nodal lineshapes in bacteriochlorophyll monomers versus photosynthetic reaction centers (RCs).
- Bacteriochlorophyll nodal lines arise from wavepacket survival on multiple electronic states.
- RC nodal lines result from coherent transfer of non-participating wavepackets to an acceptor.
Conclusions:
- Microscopic interference between electronic relaxation pathways directly influences observed CMs.
- This work resolves spectroscopic ambiguities and provides new mechanistic insights.
- Establishes CMs as a powerful tool for understanding and designing functional vibronic couplings.
Related Concept Videos
01:27π Electron Effects on Chemical Shift: Overview
1.1K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.1K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.1K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
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...
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...
1.1K
01:24IR Spectroscopy: Molecular Vibration Overview
2.5K
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
2.5K
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
1.2K
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as...
1.2K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
1.6K
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this...
1.6K
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
1.4K
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to...
According to Hooke's law, the vibrational frequency is directly proportional to...
1.4K