The Dodson Group develops experimental tools to study and control chemical reactions at the quantum level. Our focus is on exploring how reactivity is governed by the internal states of molecules—such as nuclear spin, vibrational energy, or conformational structure—under cold and low-pressure conditions. These are the regimes where quantum effects begin to contribute, where classical assumptions break down, and where new insight into fundamental mechanisms becomes accessible. 

We use buffer-gas cooling, matrix-isolation spectroscopy, cavity-enhanced techniques, and synchrotron-based photoionization mass spectrometry to trap, detect, and study reactive intermediates, weakly bound complexes, and transient radicals. Our work intersects reaction kinetics, light/matter interactions,and state-resolved chemistry, providing foundational data for modeling reaction pathways, utilizing next-generation materials and catalysts, and applying our findings to increased understanding of the chemistry of space. 

Quantum-State Control in Porous Materials 
We are establishing porous crystalline materials as platforms for preparing molecules in specific nuclear-spin isomer states (e.g., ortho- and para-H₂, CH₄, H₂O). These experiments operate under cryogenic conditions where quantum control is feasible. We recently demonstrated that porous materials can be cooled and spectroscopically interrogated without degradation—an essential step toward realizing efficient nuclear-spin enrichment. 
Frimpong, McLane, et al., Phys. Chem. Chem. Phys.,2024, https://doi.org/10.1039/D4CP02338B 

Cold Reactions and Ion–Molecule Dynamics 
Our group studies non-Arrhenius ion–molecule reactions at low temperatures, such as radiative association, that are inaccessible under typical laboratory conditions. Using custom-built buffer-gas beam sources and ion traps, we explore how translation, rotation, and quantum state selection influence chemical reactivity. We focus especially on reaction pathways for organometallic formation, using molecules like HCN and HC₃N as testbeds. 
Howard et al., J. Mol. Spec., 2024, https://doi.org/10.1016/j.jms.2024.111953 
Howard et al., J. Phys. Chem. Lett., 2025, https://doi.org/10.1021/acs.jpclett.5c00724 

Matrix-Isolated Chemistry and Surface Effects 
We use matrix-isolation infrared spectroscopy to trap molecules in inert solid environments at 10–30 K, enabling us to detect weak intermolecular forces, conformational preferences, and transient species that are otherwise too unstable to observe. Our recent work has shown that surface morphology and deposition angle in cryogenic matrices can selectively enrich molecular conformers, and that organohalogens can drive HCN clustering relevant to prebiotic polymerization. 
Hockey et al., J. Chem. Phys., 2024, https://doi.org/10.1063/5.0188433 
Hockey et al., J. Phys. Chem. A, 2022, https://doi.org/10.1021/acs.jpca.2c00716

Direct Spectroscopic Detection of Reaction Intermediates 
We collaborate with national laboratories to use tunable vacuum ultraviolet (VUV) light and time-resolved mass spectrometry to directly observe elusive species involved in reaction mechanisms. In a recent study, we made the first gas-phase detection of the singlet carbene hydroxymethylene (HCOH) and characterized its reactivity with O₂ —an experimental benchmark for carbene chemistry in the absence of solvents.
Hockey et al., J. Am. Chem. Soc., 2024, https://doi.org/10.1021/jacs.4c03090 

For updates on our research, visit our website: chem.umd.edu/dodson.