Related Experiment Video
Updated: May 18, 2026
15:58
Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Reactant-product quantum coherence in electron transfer reactions
1Department of Physics, University of Crete, Heraklion 71103, Greece.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 26, 2012
Summary
Quantum superposition states between reactants and products are suppressed in electron transfer reactions due to intermediate states. This finding impacts understanding quantum dynamics in radical-ion-pair reactions.
Area of Science:
- Quantum Chemistry
- Chemical Physics
- Theoretical Chemistry
Background:
- Electron transfer reactions are fundamental in chemistry and biology.
- Quantum superposition is a key concept in quantum mechanics.
- Understanding quantum dynamics is crucial for reaction mechanisms.
Purpose of the Study:
- To investigate the physical meaning and prevalence of quantum superposition states in electron transfer reactions.
- To determine the conditions under which these superposition states exist or are suppressed.
- To relate quantum coherences to the dynamics of spin-selective radical-ion-pair reactions.
Main Methods:
- Theoretical investigation of quantum superposition states.
- Perturbation theory analysis.
- Feynman diagrams for intuitive description.
Main Results:
- Quantum superposition states between reactants and products are strongly suppressed in electron transfer reactions.
- These superpositions do not pertain to leading orders of perturbation theory.
- An intermediate manifold of states separates reactants from products, causing suppression.
Conclusions:
- Quantum superposition is generally not a valid description for the transition between reactants and products in electron transfer reactions.
- The suppression is explained by the presence of intermediate states.
- This work provides insights into the quantum dynamics of radical-ion-pair reactions.
Related Concept Videos
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:27π Electron Effects on Chemical Shift: Overview
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, resulting in...
02:45E2 Reaction: Kinetics and Mechanism
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:16Energy Transfer in Chemical Reactions
Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ones formed. In general, kinetic energy is the form of energy powering any type of matter in motion. Imagine a person building a brick wall. The energy it takes to lift and place one brick on top of another is the kinetic energy—the energy matter possesses because of its motion. Once the wall is in place, it stores potential energy. Potential...