In this thesis, I present a new method we developed to study low frequency (< 700 cm⁻¹) vibrational dynamics: Time-resolved third-harmonic generation (TRTHG) spectroscopy. Among a variety of vibrational spectroscopy techniques, TRTHG differentiates itself with robustness, versatility, and simplicity. In TRTHG experiment, that involves only two ultrashort laser pulses, the...
In this dissertation, my research work on excited state dynamics of small organic molecules in solutions is presented. Using femtosecond stimulated Raman spectroscopy (FSRS) as the main experimental tool, the excited state hydrogen-bonding dynamics (ESHBD) of Coumarin 102, a common laser dye molecule, in ethanol solution is examined with <150...
The development and applications of a 0.2 cm⁻¹ resolution
Nd-YAG laser powered coherent anti-Stokes Raman
spectroscopy, CARS, spectrometer for gas phase studies is
chronicled in this thesis. Applications including CARS
lineshape analysis, resonant CARS, and CARS of transient
species and excited state molecules is reported.
The intensity of the signal...
Applications of several methods of coherent nonlinear Raman Spectroscopy have been made in this thesis research. The theory and potential of one of these, Photoacoustic Raman Spectroscopy (PARS), is discussed in chapter two. Experimental results are presented which illustrate the sensitivity of this method and establish sampling conditions for maximum...
The CARS apparatus at OSU was modified to permit studies in the 0-500 cm⁻¹ spectral region. The new low frequency capabilities were then used to study molecular clusters formed in free expansion jets of carbon dioxide. A strong cluster band was observed at 73 cm⁻¹, with a weaker shoulder at...
The techniques of coherent anti-Stokes Raman spectroscopy (CARS)
and inverse Raman spectroscopy (IRS) are used to examine carbon dioxide
aggregation in a supersonic jet expansion. To promote the formation of
small clusters, a BMW injector valve is modified to permit its use as a
pulsed nozzle at very cold temperatures....
The high resolution stimulated Raman spectrometer at OSU was
modified to improve its sensitivity and to extend its range of
applications to low Raman shifts and to the spectroscopy of solids and
liquids. As part of the characterization of the spectrometer, optical
Stark effects on rotational and vibrational transitions of...