The frequency-domain infrared spectrum of ammonia encodes changes in molecular dynamics caused by a DC electric field
Author(s)
Park, Youngwook; Kang, Hani; Field, Robert W; Kang, Heon
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Ammonia is special. It is nonplanar, yet in v = 1 of the umbrella mode (ν2) its inversion motion is faster than J = 0↔1 rotation. Does the simplicity of the Chemist’s concept of an electric dipole moment survive the competition between rotation, inversion, and a strong external electric field? NH3 is a favorite pedagogical example of tunneling in a symmetric double-minimum potential. Tunneling is a dynamical concept, yet the quantitative characteristics of tunneling are expressed in a static, eigenstate-resolved spectrum. The inverting-umbrella tunneling motion in ammonia is both large amplitude and profoundly affected by an external electric field. We report how a uniquely strong (up to 108 V/m) direct current (DC) electric field causes a richly detailed sequence of reversible changes in the frequency-domain infrared spectrum (the v = 0→1 transition in the ν2 umbrella mode) of ammonia, freely rotating in a 10 K Ar matrix. Although the spectrum is static, encoded in it is the complete inter- and intramolecular picture of tunneling dynamics.
Date issued
2019-11Department
Massachusetts Institute of Technology. Department of ChemistryJournal
Proceedings of the National Academy of Science of the United States of America
Publisher
National Academy of Sciences
Citation
Park, Youngwook, et al. "The frequency-domain infrared spectrum of ammonia encodes changes in molecular dynamics caused by a DC electric field." Proceedings of the National Academy of Science of the United States of America 116, 47 (2019): p. 23444-47 doi 10.1073/pnas.1914432116 ©2019 Author(s)
Version: Final published version
ISSN
1091-6490