RAMAN MICROSPECTROSCOPIC IMAGING AND MULTIVARIATE ANALYSIS TO INVESTIGATE THE CHEMICAL PROPERTIES OF NOVEL GEOLOGICAL AND PLANETARY MATERIALS by Joseph P. Smith A dissertation submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry and Biochemistry Spring 2017 © 2017 Joseph P. Smith All Rights Reserved RAMAN MICROSPECTROSCOPIC IMAGING AND MULTIVARIATE ANALYSIS TO INVESTIGATE THE CHEMICAL PROPERTIES OF NOVEL GEOLOGICAL AND PLANETARY MATERIALS by Joseph P. Smith Approved: __________________________________________________________ Murray V. Johnston, Ph.D. Chair of the Department of Chemistry and Biochemistry Approved: __________________________________________________________ George H. Watson, Ph.D. Dean of the College of Arts and Sciences Approved: __________________________________________________________ Ann L. Ardis, Ph.D. Senior Vice Provost for Graduate and Professional Education I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ Karl S. Booksh, Ph.D. Professor in charge of dissertation I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ John T. Newberg, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ Lars Gundlach, Ph.D. Member of dissertation committee I certify that I have read this dissertation and that in my opinion it meets the academic and professional standard required by the University as a dissertation for the degree of Doctor of Philosophy. Signed: __________________________________________________________ Louis A. Obando, Ph.D. Member of dissertation committee ACKNOWLEDGMENTS The research presented in this dissertation was accomplished with the support of many people. I first and foremost would like to acknowledge and deeply thank my research advisor, Dr. Karl S. Booksh, for his guidance and mentorship. Furthermore, the research accomplished in this dissertation would not have been possible without Dr. Booksh’s support, and I sincerely thank him for allowing me to perform chemical research under his advisement. Additionally, I would like to thank the members of my dissertation committee—Dr. John T. Newberg, Dr. Lars Gundlach, and Dr. Louis A. Obando—for all of their tremendous help and advice with my research. I would also like to thank Dr. Steven Brown for his guidance with my research. In addition, I would like to thank Dr. Billy P. Glass and Dr. Frank C. Smith for their help and geological expertise on the research presented within this dissertation. Finally, I would like to acknowledge the numerous collaborators that I have been lucky enough to work with during my time at the University of Delaware, including Dr. Tsu-Wei Chou, Dr. Raul F. Lobo, Dr. Dionisios G. Vlachos, Dr. Alexandra E. Krull-Davatzes, Dr. Bruce M. Simonson, Dr. Peter B. Leavens, and Dr. Brian J. Bahnson. Funding of the research accomplished throughout this dissertation is also immensely appreciated. Specifically, support of this research by both the National Science Foundation (Chem312184) and the Delaware Space Grant College and Fellowship Program (NASA Grant NNX15A119H) is gratefully acknowledged. Moreover, I would like to specifically thank the NASA Delaware Space Grant College and Fellowship Program for awarding me their graduate fellowship in 2016-2017 to iv perform chemical research. Additionally, I would like to thank both Dr. Karl S. Booksh and Dr. Sharon Rozovsky for allowing me to be a mentor and research assistant for the Science and Engineering Leadership Experience Research Experience for Undergraduates (SELI-REU) Program, which is funded by the National Science Foundation. I would also like to acknowledge the Society for Applied Spectroscopy (SAS) for both allowing me to be the President of the University of Delaware’s Student Chapter and for the Bruce R. Kowalski Award given to outstanding young researchers in the field of chemometrics. In addition, I would like to recognize the Eastern Analytical Symposium (EAS) for their Graduate Student Award sponsored by Merck & Co., Inc. for research in analytical chemistry. I would like to additionally thank the University of Delaware for the Excellence in Teaching Award. Finally, I would like to thank the Department of Chemistry and Biochemistry at the University of Delaware for the Elizabeth Dyer Award for excellence in teaching and for the Glenn S. Skinner Memorial Award for distinction in scholarship, research, and service. Overall, I am deeply appreciative of the remarkable support I have received throughout my time at the University of Delaware. Finally, the research presented in this dissertation was accomplished with the support of many friends and family throughout my career at the University of Delaware. Specifically, the members of Dr. Karl S. Booksh’s research group, both past and present, are gratefully acknowledged. I am also utmost thankful for the support from Mackenzie L. Lauro, who has not only taught me about research given her expertise, but has truly inspired me and fostered my personal growth enormously. I would also like to thank Christopher Arble for his support as well as the members of the analytical and physical chemistry divisions for their help. Finally, I would like to v thank my family members, especially my mother Deborah Smith, my father Raymond J. Smith, my brother Raymond P. Smith, my sister Jennifer Loria, and my brother-in- law Louis Loria for all of their support during my time at the University of Delaware. Overall, without the support of a myriad of people, the work accomplished in this dissertation would not be possible, and I want to deeply thank everyone who has helped throughout my time at the University of Delaware. vi TABLE OF CONTENTS LIST OF TABLES ........................................................................................................ xi LIST OF FIGURES ...................................................................................................... xii ABSTRACT ................................................................................................................ xix Chapter 1 INTRODUCTION .............................................................................................. 1 1.1 Raman Spectroscopy ................................................................................. 1 1.2 Raman Microspectroscopic Imaging ......................................................... 5 1.3 Multivariate Analysis Methods and Chemometrics .................................. 9 1.4 Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) 13 1.5 Combining Multivariate Analysis with Raman Microspectroscopic Imaging .................................................................................................... 15 2 RAMAN MICROSPECTROSCOPIC IMAGING WITH MULTIVARIATE CURVE RESOLUTION-ALTERNATING LEAST SQUARES (MCR- ALS) APPLIED TO THE HIGH-PRESSURE POLYMORPH OF TITANIUM DIOXIDE, TiO2-II ....................................................................... 19 2.1 Abstract .................................................................................................... 19 2.2 Introduction ............................................................................................. 20 2.3 Materials and Methods ............................................................................ 25 2.3.1 Sample Preparation ...................................................................... 25 2.3.2 Scanning Electron Microscopy (SEM) ........................................ 26 2.3.3 Raman Microspectroscopic Imaging ........................................... 26 2.3.4 Multivariate Data Analysis .......................................................... 28 2.3.4.1 Principal Component Analysis (PCA) .......................... 28 2.3.4.2 Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) .................................................... 30 2.4 Results and Discussion ............................................................................ 33 2.4.1 Raman Microspectroscopy .......................................................... 33 vii 2.4.2 Principal Component Analysis (PCA) and Scanning Electron Microscopy (SEM) ...................................................................... 38 2.4.3 Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) Applied to Raman Microspectroscopic Imaging ... 44 2.4.4 Evaluation of Component Selection for MCR-ALS ................... 60 2.4.5 Spatial Resolution Enhancements ............................................... 66 2.4.6 Estimated Raman Spectrum of Pure TiO2-II ............................... 70 2.4.7 Geologic Importance of Characterizing the TiO2-II-Bearing Grains using MCR-ALS Applied to Raman Microspectroscopic Imaging ....................................................... 74 2.5 Conclusions ............................................................................................