Former Group Members

Taylor is an undergraduate student studying chemical engineering and strongly considering a double major in chemistry. She is looking at the rotational spectra of mono- and di- deuterated thiazole’s vibrationally excited states. The hope is to discover how deuteration effects the spectroscopic constants of the vibrational states of thiazole. Outside of science, Taylor enjoys gardening, watching movies, and spending time in nature.

Taylor obtained her B.S. in 2023 and is currently an Intelligent Enterprise Solution Engineer at Elutions.

Recent Publication:

Esselman, B. J.; Zdanovskaia, M. A.; Adkins, T. K.; Billinghurst, B. E.; Zhao, J.; Woods, R. C.; McMahon, R. J.  Millimeter-Wave and Infrared Spectroscopy of Thiazole in its Ground State and Lowest-Energy Vibrationally Excited States (ν₁₈, ν₁₇, and ν₁₃).  J. Mol. Spectrosc. 2021, 379, 111493.  View Article

https://orcid.org/0000-0003-3802-6719

Matisha received a B.S. in Chemistry from the University of West Florida in 2016. During her undergraduate career, she worked in Dr. Karen Molek’s research lab. There, she studied the chemical kinetics of asphaltene adsorption onto nanoparticles using a home build MALDI mass spectrometer. She spent the summer of 2015 in Madison with the McMahon group and came back for graduate school to call the group home. Currently, she is working to optimize and prepare the group’s rotational spectrometer for ion spectroscopy work which will pave the way for more projects in the future. When not enjoying the sciences, Matisha spends time with her husband and two dogs, exploring Madison and keeping them out of trouble.

Matisha graduated with a PhD in 2023 and is currently a process engineer at Intel.

Recent Publication:

Dorman, P. M.; Esselman, B. J.; Zdanovskaia, M. A.; Woods, R. C.; McMahon, R. J.  The 130 – 750 GHz Rotational Spectrum of 2-Cyanopyridine – Analysis of the Ground Vibrational State and the Coriolis-Coupled Dyad of its Lowest-Energy Fundamental States. J. Mol. Spectrosc. 2023, 398, 111942.  View Article

Phoenix is a junior studying chemistry at UW-Madison with plans to get a PhD in Organic Chemistry after he graduates. He is currently studying the rotational spectrum of chloropyrazine and its isotopologues under the mentorship of Dr. Brian Esselman. When not doing research, Phoenix enjoys reading, playing board games with his girlfriend, and watching TV.

Phoenix received his BS in 2019 and is now a senior chemist at the Wisconsin Department of Transportation.

Recent Publication:

Higgins, P. M.; Esselman, B. J.; Zdanovskaia, M. A.; Woods, R. C.; McMahon, R. J., Millimeter-Wave Spectroscopy of the Chlorine Isotopologues of Chloropyrazine and Twenty-two of their Vibrationally Excited States. J. Mol. Spectrosc. 2019, 364, 111179.  View Article

https://orcid.org/0000-0002-5268-418X

Dairen received a B.S. in Chemistry from the United States Military Academy in 2014. During his time there, he worked with Dr. Nicholas Fell to study the characterization of explosive compounds using Raman Spectroscopy. He is an active duty Army Officer that mostly recently served as a Company Commander in the 82^nd Airborne Division. Outside of research, Dairen enjoys lifting, the outdoors, and spending time with family.

Dairen received his M. S. in 2023 and is currently an instructor in general chemistry at West Point.

Recent Publication:

Jean, D. R.; Wood, S. A.; Esselman, B. J.; Woods, R. C.; McMahon, R. J.  Rotational Spectroscopy of 1-Cyano-2-methylenecyclopropane (C₅H₅N) – A Newly Synthesized Pyridine Isomer. J. Phys. Chem. A, 2024, 128, 1417-1426. View Article

https://orcid.org/0000-0002-9877-0817

Sam received a B.S. in Chemistry from the University of Wisconsin – Oshkosh in 2014. While at UW Oshkosh, Sam worked under Dr. Kevin Crawford on a project involving HPLC method development for the separation of carotenoid pigments extracted from cell stains native to the Fox River. Additionaly, Sam worked under Dr. William F. Wacholtz to synthesize symmetrical bridging thiolate ligands used in closed-shell luminescent zinc (II) dimers. Since joining the McMahon group in 2016, Sam has worked on the synthesis and characterization of astrochemically relevant nitriles that are structural isomers of pyridine. Chemistry aside, Sam enjoys woodworking, fishing, camping, and committing antics.

Sam received his PhD in 2022.

Recent Publication:

Kougias, S. M.; Knezz, S. N.; Owen, A. N.; Sanchez, R. A.; Hyland, G. E.; Lee, D. J.; Patel, A. R.; Esselman, B. J.; Woods, R. C.; McMahon, R. J. Synthesis and Characterization of Cyanobutadiene Isomers – Molecules of Astrochemical Significance. J. Org. Chem. 2020, 85 (9), 5787-5798.  View Article

Danny is currently a senior pursuing a Chemistry major and is interested in sustainable energy and environmental chemistry. He is working with Sam Kougias synthesizing, isolating, and characterizing a series of novel compounds of astrochemical interest. Some of Danny’s favorite pastimes include photography, golfing, and watching the Chicago Cubs.

Danny received his BS in 2019 and is now a graduate student at Pennsylvania State University.

Recent Publication:

Kougias, S. M.; Knezz, S. N.; Owen, A. N.; Sanchez, R. A.; Hyland, G. E.; Lee, D. J.; Patel, A. R.; Esselman, B. J.; Woods, R. C.; McMahon, R. J. Synthesis and Characterization of Cyanobutadiene Isomers – Molecules of Astrochemical Significance. J. Org. Chem. 2020, 85 (9), 5787-5798.  View Article

https://orcid.org/0000-0003-0247-7075

Vanessa received a B.S. in Chemistry and a minor in Mathematics from California Lutheran University in 2014. While there she worked on the optimization of direct arylation, a type of palladium-catalyzed cross coupling, under the advisement of Dr. John F. Tannaci. Since joining the McMahon | Woods group, she has been working in the rotational spectroscopy sub-group. In collaboration with Kaori Kobayashi’s Group and John F. Stanton, she is working on the semi-equilibrium structure determination of thiophene. This project involves analysis of 20+ isotopologues and applying computational methods presented in the pyrimidine project to a sulfur-containing heterocycle. The vibrational states of thiophene below ~1100 cm^-1 have been analyzed as a separate project. Another on-going project centers on the analysis of the vibrational states of the anti-clinal conformer of 4-cyano-1,2-butadiene, which was synthesized by Sam K. with the help of undergraduate researchers and was recently published in JOC. This molecule involves the internal rotation of an asymmetric top with an asymmetric frame, and interesting coupling of the harmonics of the vibrational states that correspond to this rotation. When not working on chemistry, Vanessa enjoys singing, listening to music, walking by the Madison lakes, and traveling.

Vanessa received her PhD in 2021 and is currently BINA Program Administrator at Morgridge Institute for Research.

Recent Publication:

Orr, V. L.; Ichikawa, Y.; Patel, A. R.; Kougias, S.M.; Kobayashi, K.; Stanton, J. F.; Esselman, B. J.; Woods, R. C.; McMahon, R. J. Precise Equilibrium Structure Determination of Thiophene (C₄H₄S) by Rotational Spectroscopy – Structure of a Five-Membered Heterocycle Containing a Third-Row Atom. J. Chem. Phys.2021, 154, 244310.  View Article

https://orcid.org/0000-0001-5903-1651

Andrew received a B.S. in Chemistry from the University of North Dakota in 2015. During his time there, he worked under Professor Irina Smoliakova on an organic synthesis project related to renewable fuels as part of an REU program. After that, he worked under Professor Jerome Delhommelle on a project to characterize hydrogen sulfide phase properties using molecular dynamics simulations. Finally, he worked under Professor Mark Hofmann to carry out structure determinations of various antimony oxides using ab initio calculations.

In the McMahon group, Andrew applies computational methods and his understanding of quantum mechanics to support current and future research projects. This includes explaining the observed diastereoselectivity in the synthesis of cyanobutadienes, predicting the stability of the carbon condensation products of highly unsaturated carbon chains, and implementing a priori predictions of vibration-rotation coupling for rotational spectroscopy. Recently his focus has been on applying improved theoretical methods to the structure determinations of hydrazoic acid and pyridazine, and analyzing the dependence of the structures on the isotopologues used to obtain them.

Andrew spends a lot of his free time reading books, playing board games with his wife, and trying to find the missing puzzle pieces that her cat stole.

Andrew received his PhD in 2022 and is currently a research computing facilitator at the UW-Madison Center for High Throughput Computing.

Recent Publication:

Owen, A. N.; Esselman, B. J.; Woods, R. C.; McMahon, R. J.  Carbon Condensation via [4+2] Cycloaddition of Highly Unsaturated Carbon Chains. J. Phys. Chem. A, 2023, 127, 4277-4290.  View Article

Natalie is an undergraduate student studying chemical engineering and chemistry, and is from Boulder, CO. Her research focuses on determining highly accurate and precise semi-experimental equilibrium structural of chlorobenzene using rotational spectroscopy. Outside of chemistry, Natalie enjoys hiking, exploring Madison, and taking care of her house plants.

Natalie received her B.S. in 2024 and is now a graduate student at the University of Wisconsin-Madison.

https://orcid.org/0000-0002-3762-1842

Houston received a B.S. in Chemistry from Emory University in 2018. During his time there, he worked with Dr. Widicus Weaver to experimentally create and study interstellar ice analogues. Since joining the McMahon group, he has been working in the rotational spectroscopy sub-group. Currently, he is working on the semi-experimental equilibrium structure determination of methacrylonitrile. This structure determination involves the analysis of 20+ isotopologues accounting for internal rotation within each and applying computational corrections to determine highly precise semi-experimental structural parameters for the molecule. Another current project is a least-squares fit of a Coriolis-coupled dyad of the two lowest-energy vibrationally excited states of 2-cyanopyrimidine. This least-squares fit requires a two-state Hamiltonian to adequately model the experimental spectrum. When not doing research, Houston enjoys playing video games, spending time with family, and traveling.

Houston obtained his Ph. D. in 2023 and is currently a postdoctoral research associate at Savannah River National Laboratory.

Recent publication:

Smith, H. H.; Esselman, B. J.; Wood, S. A.; Stanton, J. F.; Woods, R. C.; McMahon, R. J.  Improved Semi-experimental Equilibrium Structure and High-Level Theoretical Structures of Ketene. J. Chem Phys. 2023, 158, 244304.  View Article

 https://orcid.org/0000-0001-9416-2278

Mayeli received a B.S. in Chemistry from Benedictine University in 2022. For their undergraduate research, they studied under Dr. David Rubush on the project of the synthesis of compound M567-0446 and analogs for quorum sensing studies in Lactobacillus acidophilus in collaboration with Dr. Tiara Perez Morales. Outside of the lab, Mayeli enjoys gardening, cooking, and playing video games.

Mayeli received their Master’s degree in 2024.

https://orcid.org/0000-0001-8204-2770

Samuel Wood received his B.S. from Iowa State University in 2016. While at ISU, Sam studied self-assembling organic radicals under the advisement of professor Arthur H. Winter. Since joining the group, Sam’s research has focused on heavy atom tunneling and synthesis of astrochemically relevant compounds. Outside of the lab, Sam enjoys yoga, camping, and cooking.

Sam received his PhD in 2024 and is currently a postdoctoral researcher at the Justus Liebig University in Giessen.

Recent Publication:

Wood, S. A.; Esselman, B. J.; Kougias, S. M.; Woods, R. C.; McMahon, R. J.  Photoisomerism of (Cyanomethylene)cyclopropane (C₅H₅N) to 1-Cyano-2-methylenecyclopropane in an Argon Matrix. J. Phys. Chem. A, 2024, 128, 1427-1437.  View Article

https://orcid.org/0000-0001-5167-8573

Maria Zdanovskaia received a B.S. in Psychology and Certificate in Mathematics from UW – Madison, but decided to pursue physical organic chemistry in graduate school.  She has been studying the rotational spectroscopy of small aromatic heterocycles and substituted aromatic compounds.   She has employed organic syntheses, rotational spectroscopy, and computational chemistry to determine the precise equilibrium (r_e^SE) structures of 1H- and 2H-1,2,3,-triazoles, thiazole, and pyridine.  These precise equilibrium structures use the rotational constants of many isotopologues and coupled-cluster calculations to produce the most accurate molecular structures possible by current methods.

Additionally, Maria has analyzed the rotational spectra of benzonitrile and its isomer phenyl isocyanide, two compounds of astrochemical interest.  She has obtained least-squares fits of their two lowest energy vibrationally excited states, which form a Coriolis-coupled dyad.  These dyad fits allow for a highly precise determination of the vibrational energy difference due to the transitions involved in sharp resonances and nominally forbidden interstate transitions.  Using a sample of 2-cyano-1,3-butadiene prepared by Sam K., Maria has obtained the rotational spectrum of the ground state of this molecule.

Maria assisted in the measurement, assignment, and least-squares fitting 2-chloropyridine and 2-chloropyrazine.  Due to the many well-isolated vibrationally excited states accessible for these molecules, spectroscopic constants for over 20 vibrational states were obtained.  These works allowed for a comparison between the experimental and computational vibration-rotation interaction constants.

Maria is also engaged in developing materials for chemical education using computational molecular modeling, including a website generated for organic laboratories at collaborating community colleges that is free for use by all interested individuals.  She has worked with a couple of high school teachers to help implement the use of computational chemistry at the high school level.  When not doing chemistry, Maria enjoys dancing, jigsaw puzzles, various crafts, writing Excel macros, and instigating innocent mischief.

Maria received her PhD in 2022. She is a senior scientist in the Madison area and continues to work closely with the McMahon | Woods group.

Recent Publication:

Zdanovskaia, M. A.; Franke, P. R.; Esselman, B. J.; Billinghurst, B. E.; Zhao, J.; Stanton, J. F.; Woods, R. C.; McMahon, R. J.  Vibrationally Excited States of 1H- and 2H-1,2,3-Triazole Isotopologues Analyzed by Millimeter-wave and High-Resolution Infrared Spectroscopy with Approximate State-Specific Quartic Distortion Constants.  J. Chem. Phys. 2023, 158, 044301.  View Article