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Published on: June 28, 2018
Stark spectroscopy of mixed-valence systems
Lisa N Silverman1, Pakorn Kanchanawong, Thomas P Treynor
1Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
Summary
Stark spectroscopy quantifies charge delocalization in mixed-valence systems. Analyzing changes in electric dipole moments reveals insights into electron transfer, even in complex environments like photosynthetic reaction centers.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Materials Science
Background:
- Mixed-valence systems exhibit distinct electronic states with varying electric dipole moments.
- These states are interconvertible via intervalence charge transfer (ICT) transitions.
- ICT transitions are influenced by charge transfer distance and electron delocalization.
Purpose of the Study:
- To investigate the application of Stark spectroscopy for quantifying electron delocalization in mixed-valence systems.
- To explore the complexities of Stark analysis, including classical and non-classical effects on bandshape.
- To demonstrate the utility of Stark spectroscopy in well-defined, complex environments.
Main Methods:
- Utilizing Stark spectroscopy to probe changes in electric dipole moments of ICT transitions.
- Analyzing Stark spectra to extract quantitative information on charge delocalization.
- Examining the influence of external electric fields on transition band positions and intrinsic bandshapes.
- Addressing complications from inhomogeneous broadening in immobilized samples.
Main Results:
- Stark spectroscopy provides quantitative data on the degree of electron delocalization in mixed-valence compounds.
- Classical Stark analysis is applicable in limiting cases, while intermediate cases exhibit complex, non-classical Stark effects influencing bandshapes.
- Detailed analysis is feasible even in intricate systems, such as the radical cation of the special pair in photosynthetic reaction centers.
Conclusions:
- Stark spectroscopy is a powerful tool for characterizing electron delocalization in mixed-valence systems.
- Understanding non-classical Stark effects is crucial for accurate analysis of bandshapes and parameters.
- The method's applicability extends to complex biological systems, offering insights into charge transfer dynamics.
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