Former Group Members

Recent Group Alumni

Taylor Adkins

Credentials: Undergraduate Researcher


Taylor is a third-year 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.

Brent K. Amberger

Credentials: Ph.D.

Brent Amberger received his B.A. in chemistry from Amherst College in 2008.  At Amherst, Brent spent time working with Professor David Hansen synthesizing molecularly imprinted polymers.  Later, he did his undergraduate thesis research with Professors Helen Leung and Mark Marshall, using microwave spectroscopy in the structural determination of small gas phase Van der Waals complexes.  At Wisconsin, Brent worked with Professor McMahon in the collaborative rotational spectroscopy sub-group with Brian Esselman and Professor R. Claude Woods.  He used a glow-discharge, millimeter-wave spectrometer to observe rotational transitions for small organic molecules.  Once rotational spectra for these compounds are known, they can be searched for in space using radio telescopes.  Brent owns many things, including a canoe, a cat, and a clownfish.

Brent graduated with a PhD in 2015 and is currently a Senior Researcher at Allergy Amulet in Lowell, MA.

Recent publication:

Amberger, B. K.; Esselman, B. J.; Stanton, J. F.; Woods, R. C.; McMahon, R. J. Precise Equilibrium Structure Determination of Hydrazoic Acid (HN3) by Millimeter-wave Spectroscopy. J. Chem. Phys. 2015, 143, 104310.  View Article

Brandon Dobraska

Credentials: B.S.


Brandon is a Senior at UW Madison pursuing a B.S. in chemistry and is currently working under the guidance of Andrew Owen on computational chemistry. In his time that strays from the academic in nature, Brandon loves fishing and routinely explores new bodies of water. He also enjoys cruising country backroads on his new motorcycle.

Brandon received his Bachelor’s degree in 2017.

Matisha Dorman

Credentials: Ph.D. Candidate


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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.

Recent Publication:

Dorman, P. M.; Esselman, B. J.; Changala, P. B.; Kougias, S. M.; McCarthy, M. C.; Woods, R. C.; McMahon, R. J.  Rotational Spectrum of anti– and gauche-4-Cyano-1-Butyne (C5H5N) – an Open-Chain Isomer of Pyridine. J. Mol. Spectrosc. 2022, 385, 111604.  View Article

Madison Fellows

Credentials: Ph.D. Student


Madison received a B.A. in Chemistry and Spanish from Grinnell College in 2017. During her undergraduate career, she interned at the CRF at Sandia National Laboratory, where she studied radical reaction pathways, in addition to NREL, where she investigated the effect of biofuel pyrolysis on catalysts. At Grinnell, she studied aerosol formation and catalyst chemistry with Herbierto Hernandez. Since joining the McMahon group, Madison has been studying astrochemically relevant compounds through computation and rotational spectroscopy. Outside of chemistry, Madison enjoys doing yoga, cooking, and watching cute animal videos.

Ben C. Haenni

Credentials: Ph.D.

Ben received a B.S in Chemistry and BCMB (Biochemical,Cell, and Molecular Biology) from Drake University in 2010.  While there he worked with Dr. Gholam Mirafzal on the green applications of ionic liquids for organic synthesis.  In the McMahon Group, Ben applied computational chemistry to wide range of topics and molecules, from tunneling in carbenes to excited state calculations.  Ben eats a small variety of food.

Ben received his PhD in 2016 and now instructs at UW – La Crosse.

Zachary Heim

Credentials: B.S.


Zach is a senior chemistry major. He joined after a short project with the group as a part of the 115/116 program. He is currently working on rotational spectroscopy of pyrimidine. When not sciencing, Zach enjoys spending his time playing hockey, fishing, and travelling.

Zach received his Bachelor’s degree in 2017.

Phoenix Higgins

Credentials: B.S.


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.

Grace Hyland

Credentials: B.S.


Grace is a senior at UW Madison studying Chemistry and Spanish.  She is currently assisting Sam Kougias in the synthesis of astrochemically relevant nitriles.  When not science-ing, Grace enjoys yoga, baking, and chemistry puns.

Grace received her Bachelor’s degree in 2018.

Stephanie N. Knezz

Credentials: Ph.D.


Stephanie received a B.S. in chemistry from Butler University in 2011.  During her time there, she worked on a variety of projects with Dr. John Esteb, including a chemical education project developing experiments for the organic teaching labs and synthesis of novel β-lactams in conjunction with a small group from Eli Lilly.  In the McMahon Group, Stephanie applied matrix isolation in conjugation with various spectroscopic techniques to study reactive organic molecules. In her spare time, Stephanie enjoys seeing live music, singing, and camping.

Stephanie received her PhD in 2016, and now works at Northwestern University.

Samuel Kougias

Credentials: Ph.D.


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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 Lee

Credentials: B.S.


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.

Vanessa Orr

Credentials: Ph.D.


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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.

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

Andrew Owen

Credentials: Ph.D.


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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 lecturer at UW–Madison.

Recent Publication:

Owen, A. N., Sahoo, N. P.; Esselman, B. J.; Stanton, J. F.; Woods, R. C.; McMahon, R. J.  Semi-Experimental Equilibrium (reSE) and Theoretical Structures of Hydrazoic acid (HN3).  J. Chem. Phys. 2022, 157, 034303.  View Article

Cara Schwarz

Credentials: M.S.


Cara graduated from UW Madison with a B.S. degree in chemistry. She is currently working on rotational spectroscopy of phenyl isocyanate. Aside from chemistry, she enjoys skiing, Rubik’s cubes, and spending time outside.

Cara received her Master’s degree in 2017.

Cara is now a member of the Stowe Research Group at UW-Madison.

Maria Zdanovskaia

Credentials: Ph.D.


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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 (reSE) 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.; Esselman, B. J.; Kougias, S. M.; Amberger, B. K.; Stanton, J. F.; Woods, R. C.; McMahon, R. J.  Precise Equilibrium Structures of 1H- and 2H-1,2,3-Triazoles (C2H3N3) by Millimeter-wave Spectroscopy.  J. Chem. Phys. 2022, 157, 084305.  View Article

Ph.D. Graduates

Dr. Steven W. Albrecht
Business Development Manager
Ph.D. 1995 (RJM #4)

Dr. Eric S. Ball
Department of Chemistry
Metropolitan State College
Ph.D. 2000 (RJM #12)

Professor Nicola J. Burrmann
Heartland Community College
Ph.D. 2010 (RJM #22)

Dr. Terence M. Barnhart
Senior Director of Straegy and Continuous Improvement
Ph.D. 1993 (RJM #2)

Professor Paul A. Bonvallet
Department of Chemistry
College of Wooster
Ph.D. 2001 (RJM #13)

Professor Nathan P. Bowling
Department of Chemistry
University of Wisconsin-Stevens Point
Ph.D. 2005 (RJM #16)

Dr. Eric M. Breitung
General Electric Company
Ph.D. 1999 (RJM #10)

Dr. Jeffrey T. DePinto
Air Products and Chemicals
Ph.D. 1993 (RJM #3)

Professor Wendy A. deProphetis
Department of Chemistry and Physics
Wagner College
Ph.D. 2004 (RJM #15)

Dr. Brian J. Esselman
Department of Chemistry
University of Wisconsin
Ph. D. 2012 (RJM #27)

Dr. Robert J. Halter
Myriad Pharmaceuticals, Inc.
Ph.D. 2002 (RJM #14)

Dr. Jonathan A. Hodges
Affinergy, Inc.
Ph.D. 2000 (RJM #11)

Professor Carl R. Kemnitz
Department of Chemistry
California State University Bakersfield
Ph.D. 1995 (RJM #7)

Dr. Yong Seol Kim
Bergische Universität Wuppertal
Ph.D. 2005 (RJM #17)

Dr. Laura A. Kopff
Ph.D. 2012 (RJM #26)

Dr. Kevin L. Kott
The Procter and Gamble Company
Ph.D. 1993 (RJM #1)

Dr. Susan P. Lucas
Ph.D. 2006 (RJM #18)

Professor Jessica L. Menke
University of Wisconsin – Whitewater
Ph.D. 2010 (RJM #23)

Professor Eric V. Patterson
Truman State University
Ph.D. 2010 (RJM #8)

Professor Caroline R. Pharr
Mercyhurst College
Ph.D. 2008 (RJM #20)

Dr. Randal A. Seburg
Merck Research Laboratories
Ph.D. 1995 (RJM #6)

Dr. Christopher J. Shaffer Institute of Organic Chemistry
and Biochemistry AS CR, v.v.i.
Ph.D. 2010 (RJM #24)

Professor Louise L. Stracener
Department of Natural Science
Edgewood College
Ph.D. 1998 (RJM #9)

Dr. Phillip S. Thomas
Ohio State University (Post-Doc)
Ph.D. 2007 (RJM #19)

Professor Craig M. Whitaker
Department of Chemistry
U.S. Naval Academy
Ph.D. 1995 (RJM #5)

Dr. Katherine (Traynor) Windsor
Department of Chemistry
Vanderbilt University
Ph.D. 2010 (RJM #21)

M.S. Graduates

Brian Barnes
M.S. 1998

Susie Belal
M.S. 1998

Sean Birke
Jefferson College
M.S. 1990

Beatriz DeGuia
M.S. 2004

Prof. Nancy Carter Dopke
Mercer University
M.S. 1996

Thomas Draxler
M.S. 2011

Ryan Fimmen
Ohio State University
M.S. 1998

Terese A. (Kreifels) Waltz
M.S. 2012

Alex Nolan
M.S. 2011

Kathleen Pollock
Cedarburg High School
M.S. 1995

Zoe M. Samer
M.S. 2013

Cara E. Schwarz
M.S. 2017

Nicholas A. Walters
M.S. 2016

Jim Zdrodowski
M.S. 1994


Kris Andersen

Scott Aulinskis

Caroline Breitkreuz

Mathew J. Biller
University of Wisconsin

Kevin Carlisle

Ed Choi
Guilford Pharmaceuticals

Dr. Andrew P. Combs
Bristol Myers Squibb

Mitch A. Daane
University of Wisconsin – Madison Athletic Department

Brandon Dobraska

Kyle A. Hecker
Eli Lilly and Company

Phoenix M. Higgins

Grace E. Hyland

Jayson Kempinger
University of Nebraska

Aaron Kunzer
Abbott Laboratories

John Lansdown

Mike Larson

Danny J. Lee

Ibrain Marcano

Aatmik R. Patel

Ryan Powers

Craig C. Price
University of Wisconsin

Jeff Rauh

Rodrigo A. Sanchez

Paul Severin

Jeffery M. Slosarczyk

Tom Spaulding

Colleen C. Sylvester

Eric M. Todd
Department of Chemistry
University of Illinois

Dr. Tammy C. Turek-Etienne
Invitrogen Drug Discovery Solutions
Madison, WI 53719