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| Searle Chemical Laboratory 023 |
| Searle Chemical Laboratory 023 |
| 773-834-1877 |
| 773-702-0805 |
| moran@uchicago.edu |
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| Ph.D. Physical Chemistry, Kansas State University |
| B.S. Chemistry, University of Nebraska at Omaha |
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| Optical properties of an organic chromophore assembly depend on interactions between the individual units that comprise the assembly. At one extreme, the units do not interact and the properties of the assembly are determined solely by the identities of the constituents. However, the properties of the assembly become increasingly collective as the inter-unit interaction strengthens. A clear physical picture is not easily revealed using linear measurements due to the complexity of the problem and limited number of dependent variables. We therefore use nonlinear time-resolved methods such as the pump-probe, transient anisotropy, and photon-echo techniques to extract this information. Studies of novel monomer and dimer molecular systems are currently underway.
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| An amplified Ti:Sapphire laser system and OPA were recently built to study nonlinear responses at a variety of visible wavelengths. The laser produces 50 fs pulses centered at 800 nm. The OPA is a two-stage design in which the near-infrared portion of a continuum is amplified in KNBO3, then either doubled (SHG) or summed with an 800 nm pulse (SFG) in a BBO crystal to produce visible pulses tunable from 450-750 nm. The transparency range and large nonlinear coefficient of KNBO3 are advantageous for generating wavelengths less than 470 nm. Spectra of the OPA output for the wavelength range in which we are now working are shown below along with a spectrogram of a compressed pulse.
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