Scott N. Goldie, PhD - MSU Research Experience

I attended Michigan State University from August, 1995 to August 2000, as a Ph.D. graduate student of Analytical Chemistry Professor Gary J. Blanchard. I was trained as a measurement scientist, with a dissertation that included experiences in basic research at the interfaces between Analytical and Physical Chemistry, and applied research between Analytical Chemistry and Chemical Engineering. I also gained some basic experiences in synthetic organic chemistry, much to the entertainment of my organic colleagues. My graduate work extended my undergraduate studies by continuing to perform experiments that can elucidate information about local environments in the condensed phase.

A fundamental understanding of intermolecular interactions is required to achieve predictability in liquid-phase systems. Using a picosecond pump-probe laser spectrometer to detect stimulated emission, illustrated above, we have studied solution phase local organization by measuring induced orientational anisotropy and vibrational population relaxation dynamics. We have studied perylene and 1-methylperylene in a series of normal alkanols (methanol to decanol), and selected aliphatic aldehydes and ketones, to probe local organization in low viscosity liquids. The reorientation behavior of the chromophores in the n-alkanol solvents is different than that seen in n-alkanes. The T₁ data for the ring breathing vibrational modes of these same chromophores points to efficient and solvent-dependent relaxation. We can infer from these data the type of local organization characteristic of the alkanols.

In both the aliphatic aldehydes and the ketones, there is a change in the nature of the solvent-solute interactions with both probe molecules as the hydrodynamic volume of the solvent molecules approaches that of the probes. The solvent-dependent change in behavior occurs for different solvent aliphatic chain lengths in the two systems. Vibrational population relaxation measurements for two probe molecule vibrational modes reveal efficient intermolecular coupling in all cases. The data point to the role of the solvent aldehyde proton in mediating solvent-solvent and solvent-solute interactions, leading to chromophore dynamics reminiscent of those seen in the n-alcohols. Reorientation of the two probes in the ketones yields results that are more consistent with those seen in the alkanes, suggesting the relative weakness of dipole-induced dipole interactions relative to H-bonding interactions in the solvation of perylene and 1-methylperylene. Publications that resulted from this work include "Orientational and Vibrational Relaxation Dynamics of Perylene and 1-Methylperylene in Aldehydes and Ketones" J. Phys. Chem. A., 2001, 105 (28), 6785 and "Orientational and Vibrational Relaxation Dynamics of Perylene and 1-Methylperylene in n-Alcohols: Probing the Balance between van der Waals and Hydrogen-Bonding Interactions" J. Phys. Chem. A., 1999, 103 (8), 999.

We have also applied transient spectroscopies to the characterization of polymer curing for a deep-UV, chemically amplified polymer photoresist used in the fabrication of semiconductors. We characterized changes in polymer free volume as a function of cure using ground state recovery measurements of crystal violet, a probe molecule doped in the polymer matrix. These data, in conjunction with linear spectroscopy, will ultimately be used to provide insight into the diffusional behavior of protons in the polymer matrix as a function of cure. We have published these findings in "Spectroscopic Characterization of Acid Generation and Concentration and Free Volume Evolution in Chemically Amplified Resists" J. Vac. Sci. Tech. B., 2002, 20 (1), 219 , "Spectroscopic Characterization of Acid Mobility in 248nm Chemically Amplified Resists" Polym. Mater. Sci. Eng., 2000, 82, 48, "Spectroscopic Characterization of Acid Mobility in Chemically Amplified Resists" Proceedings of SPIE - International Society of Optical Engineering Advances in Resist Technology and Processing XVII, 2000, 3999, 355 and "Characterizing Acid Mobility in Chemically Amplified Resists via Spectroscopic Methods" Proceedings of SPIE - International Society of Optical Engineering Advances in Resist Technology and Processing XVI, 1999, 3678, 161.