Powerful spectroscopic techniques increasingly involve nonlinear processes that arise due to the convolution of more than one electric field - input laser pulse. Analyzing the output of optical processes like these demands the utilization of deterministic improvement tools. Three-color coherent Raman scattering represents a complex non-degenerate four wave mixing process that includes contributions from both resonant and non-resonant interaction of the three input fields to generate a signal. In order to quantify these contributions, effective differentiation of the non- resonant (background) from the resonant (coherent signal) is required. These contributions can be differentiated based on how the molecular vibrational modes are being excited by the input pulses. The work described here demonstrates the ability of second-order correlation spectroscopy, applied along with an all-Gaussian theoretical model to analyze three color coherent Raman scattering processes. It is shown to discriminate between resonant versus non-resonant four wave mixing processes successfully. A robust, femtosecond/picosecond coherent Raman spectroscope is used to observe how the resonant signal builds up in a finite amount of time for different specimens and how it is can be controlled by input laser pulse shaping. A closed-form solution obtained via an all-Gaussian approach provides confirmatory theoretical proof of the experimental results obtained. This technique is used to study hydrogen bonding, which is a vital molecular interaction for bio-molecular systems and yet lacks a profound understanding of its ways of forming complexes. Furthermore, a novel second-order one-dimensional correlation function is introduced that replicates the results of the diagonal sum of the traditional synchronous two- dimensional correlation function, thus reducing a two-dimensional analysis to one-dimension. Along with the first demonstration of these analyses for coherent Raman scattering, a generalized approach is described, which opens up research opportunities to investigate these optical processes' dependence on multiple controlling parameters.

In thisproject, solubility of butyl paraben in 7 puresolvents and 5 ethanol aqueous solvents has been determined at from 1 ℃to 50 ℃. Thermodynamic properties of butyl paraben have been measured by DifferentialScanning Calorimetey. Relationship between molar solubility of butyl paraben in6 pure solvents and thermodynamic properties has been analyzed. Thisrelationship suggests a method of estimating activity of solute at equilibrium fromcombining solubility data with DSC measurements. Then, activity coefficient accordingto the solubility at different temperatures can be estimated. Duringthe solubility measurements in ethanol aqueous solvents, it is found that whenbutyl paraben is added into aqueous solutions with certain proportion ethanol,solutions separates into two immiscible liquid layers in equilibrium. Water andethanol are primary in top layer, while the butyl paraben is primary in bottomlayer, but the solution turns to cloudy when two layers of solution are mixed. Theaim of this work was to present the phase behaviour of liquid-liquid-phaseseparation for (butyl paraben + water + ethanol) ternary system from 1 ℃ to 50 ℃at atmospheric pressure. Thearea of liquid-liquid-phase separation region in the ternary phase diagram increaseswith the increasing temperature from 10 ℃to 50 ℃. In thisstudy, more than several hundreds of nucleation experiments of butyl paraben havebeen investigated in ethyl acetate, propanol, acetone and 90% ethanol aqueoussolution. Induction time of butyl paraben has been determined at 3 differentsupersaturation levels in these solvents, respectively. Free energy ofnucleation, solid-liquid interfacial energy, and nuclei critical radius havebeen determined according to the classical nucleation theory. Statistical analysis ofinduction time reveals that the nucleation is a stochastic process with widevariation even at the same experiment condition. Butyl paraben nucleates most difficultlyin 90 % ethanol than in other 3 solvents, and most easily in acetone. The interfacialenergy of butyl paraben in these solvents tends to increasing with decreasemole fraction solubility in these solvents. Coolingcrystallizations with different proportions of butyl paraben, water and ethanolhave been observed by Focused Beam Reflectance Method, Parallel VirtualMachine, and On-line Infrared. The FBRM, IR curves and the PVM photos show someof the solutions appeared liquid-liquid phase separation during coolingcrystallization process. The results suggest that if solutions went throughliquid-liquid phase separation region during the cooling crystallizationprocess the distribution of crystals crystal was poor. Droplets from solutions withsame proportion butyl paraben but different proportions of water and ethanolhave been observed under microscope. Induction time of the droplets has been determinedunder the room temperature. Droplets from top layer or bottom layer of solutionwith liquid-liquid phase separation on small glass or plastic plates were alsoobserved under microscope. The microscope photos show that the opposite flows ofcloudy solution on the glass and the plastic plate before nucleation. The resultsof the cooling and evaporation crystallization experiments both revealed thatnucleation would be prevented by the liquid-liquid phase separation. / QC 20110630