Physical Chemistry Seminar: "Ammonia-formic acid complex: internal rotation analysis, calculations, and new microwave measurements"


4 to 5 p.m., April 8, 2024


Kristen Roehling
photo of Kristen Roehling

Student, Chemistry and Biochemistry, The University of Arizona


Our lab uses high-resolution microwave spectroscopy to determine the structure and dynamics of small molecules. Hydrogen-bonded complexes involving oxygen and nitrogen can be used as analogs to better understand DNA base pairs. In this project, the rotational spectrum of ammonia-formic acid was analyzed from 7-22 GHz using direct measurement and double resonance microwave spectroscopy. Analysis of the spectrum revealed that ammonia acts as a low-barrier internal rotor in this complex. The XIAM5 program was utilized to obtain an excellent fit for 20 A state transitions and 16 E state transitions. The fit yielded rotational constants, 14N quadrupole constants, and internal rotor parameters. The barrier to internal rotation (V3) was found to be 195.18(7) cm-1. 

Short Bio Sketch:

Kristen Roehling is an undergraduate senior majoring in chemistry and applied mathematics. For most of her undergraduate career, she has conducted research with the Kukolich group and has studied a variety of complexes using microwave spectroscopy.