Dynamics of Molecular Excitons

Chapter 1 Introduction
1.1 Motivation and objective
1.2 Frenkel and Wannier excitons
1.3 Disorder, fluctuations, and measure of delocalization
1.4 Utility and limitations of exciton models

Chapter 2 Microscopic derivation of Frenkel exciton-bath Hamiltonian
2.1 Aggregates of chromophores
2.2 Aggregates of chromophores embedded in host media
2.3 Summary and additional remarks

Chapter 3 Linear spectroscopy of molecular excitons
3.1 Absorption lineshape
3.2 Stimulated emission lineshape
3.3 Model calculations
3.4 Summary and additional remarks

Chapter 4 Exciton transfer rates and hopping dynamics
4.1 Transfer between two exciton states: Förster theory’s and its generalizations
4.2 Transfer between groups of exciton states
4.3 Master equation approaches and long range exciton hopping dynamics
4.4 Summary and additional remarks

Chapter 5 Quantum dynamics of molecular excitons
5.1 Projection operator formalism
5.2 Second order approximations
5.3 Fourth order approximations
5.4 Harmonic oscillator bath with linear coupling
5.5 Summary and additional remarks

Chapter 6 Excitons and quantum light
6.1 Interaction of materials with quantum light
6.2 Microscopic derivation of Förster’s spectral overlap expression
6.3 Polariton
6.4 Summary and additional remarks

Chapter 7 Time-resolved nonlinear spectroscopy of excitons
7.1 General assumption of material Hamiltonian
7.2 Two-pulse spectroscopy
7.3 Four wave mixing spectroscopy
7.4 Summary and additional remarks

Chapter 8 Examples and applications
8.1 Excitons in natural light harvesting complexes
8.2 Excitons for photovoltaic devices
8.3 Excitons for structural determination
8.4 Summary and additional remarks

A.1 Solution of eigenvalue problems for the simple Frenkel exciton models
A.2 Some identities for averages involving harmonic oscillator models

Dynamics of Molecular Excitons provides a comprehensive, but concise description of major theories on the dynamics of molecular excitons, intended to serve as a self-contained resource on the topic. Designed to help those new to this area gain proficiency in this field, experts will also find the book useful in developing a deeper understanding of the subject.

The starting point of the book is the standard microscopic definition of molecular Hamiltonians presented in commonly accepted modern quantum mechanical notations. Major assumptions and approximations involved in constructing Frenkel-type exciton Hamiltonians, which are well established, but are often hidden under arcane notations and approximations of old publications, are presented in detail. This will help quantum chemists understand the major assumptions involved in the definition of commonly used exciton models.

Rate theories of exciton dynamics, such as Förster and Dexter theories and their modern generalizations, are presented in a unified and detailed manner. In addition, important aspects that are often neglected, such as local field effect and the role of fluctuating environments, are discussed. Various quantum dynamics methods allowing coherent dynamics of excitons are presented in a systematic manner in the context of quantum master equations or path integral formalisms. The author also provides a detailed theoretical explanation for the major spectroscopic techniques probing exciton dynamics, including modern two-dimensional electronic spectroscopy, with a critical assessment of the implications of these spectroscopic measurements. Finally, the book includes a brief overview of major applications including an explanation of organic photovoltaic materials and natural light harvesting complexes.

• Covers major theories of exciton dynamics in a consciously concise and easily readable way
• Bridges the gap between quantum dynamics working with phenomenological exciton Hamiltonian and quantum chemistry construct reliable models amenable for dynamics calculations from ab initio calculations
• Explores modern nonlinear electronic spectroscopy techniques to probe exciton dynamics, showing how it is applied

Materials scientists, engineers and physics scientists working in the areas of spectroscopy, exciton dynamics and photonics