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Updated: Feb 3, 2026

Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy
Published on: August 13, 2019
Fundamental vibration frequency and rotational structure of the first excited vibrational level of the molecular
Paul Jansen1, Luca Semeria1, Frédéric Merkt1
1Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
Abstract:
The term values of the rotational levels of the first excited vibrational state of the electronic ground state of with a rotational quantum number N + ≤ 13 have been determined with an accuracy of 1.2 × 10-3 cm-1 (∼35 MHz) by multichannel-quantum-defect-theory-assisted Rydberg spectroscopy of metastable He2. Comparison of the experimental term values with the most accurate ab initio results for available in the literature [W.-C. Tung, M. Pavanello, and L. Adamowicz, J. Chem. Phys. 136, 104309 (2012)] reveals inconsistencies between the theoretical and experimental results that increase with increasing rotational quantum numbers. The fundamental vibrational wavenumber of was determined to be 1628.3832(12) cm-1 by fitting effective molecular constants to the obtained term values.
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