Theoretical studies of pump-probe and Raman experiments on condensed phase systems
The complex nature of condensed-phase systems requires that simplifications be made in the description of the dynamics. In this thesis two possible avenues of simplification are examined; the averaging over bath degrees of freedom and the consideration of a subset of the system of interest. A theory for resonant and near-resonant ultrafast pump-probe spectroscopies of condensed-phase systems is presented. The multimode Brownian oscillator model, which accounts for both optically active and optically inactive (bath) degrees of freedom, is shown to model the features of pump-probe spectroscopies in a variety of realistic experimental configurations. Electronic dephasing, the time-dependent Stokes shift, and quantum beats are analyzed, and comparison is made to photon echo spectroscopy. Quantitative calculations are performed for femtosecond pump-probe experiments on a conjugated polymer; comparison with experimental results reveals excellent agreement between theory and experiment, both for the pump pulse tuned to the excitonic resonance and for the pump pulse tuned below that resonance. Molecular dynamics simulations are employed to calculate the Raman and infrared spectra of liquid water and water clusters in the range 0-1000 cm[sup [minus]1]. The librational peak in the Raman spectrum of the liquid has a strong dependence on the anisotropy of the assumed gas-phase polarizability tensor. The cluster results reveal that most of the spectroscopically probed dynamics of the liquid are present in clusters as small as N = 5 cluster, with some bulk-like dynamics even present in the dimer spectra. The librational peaks in the pentamer spectra redshift with increasing temperature. Molecular dynamics simulations are used to calculate the optical Kerr effect (OKE) for small rare-gas clusters, using a many-body potential based on the Drude oscillator model. Pairwise additive potentials predict the same OKE signal as does the many-body approach.
- Research Organization:
- Rochester Univ., NY (United States)
- OSTI ID:
- 7112235
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
74 ATOMIC AND MOLECULAR PHYSICS
LIQUIDS
DYNAMICS
OPTICAL PUMPING
RAMAN SPECTROSCOPY
MOLECULAR CLUSTERS
SOLIDS
DEGREES OF FREEDOM
KERR EFFECT
POLYMERS
RARE GASES
WATER
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELEMENTS
FLUIDS
GASES
HYDROGEN COMPOUNDS
LASER SPECTROSCOPY
MECHANICS
NONMETALS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PUMPING
SPECTROSCOPY
665000* - Physics of Condensed Matter- (1992-)
664200 - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)