Observation of the Low‐Frequency Spectrum of the Water Trimer as a Sensitive Test of the Water‐Trimer Potential and the Dipole‐Moment Surface. Issue 28 (28th May 2020)

• Record Type: Journal Article
• Authors: Schwan, Raffael; Qu, Chen; Mani, Devendra; Pal, Nitish; Schwaab, Gerhard; Bowman, Joel M.; Tschumper, Gregory S.; Havenith, Martina
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 28(2020)
• Page Start: 11399
• Page End: 11407
• Publication Date: 2020-05-28
• Subjects: helium nanodroplets -- vibrational spectroscopy -- water cluster -- water potential; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202003851
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Intermolecular interactions in bulk water are dominated by pairwise and non‐pairwise cooperative interactions. While accurate descriptions of the pairwise interactions are available and can be tested by precise low‐frequency spectra of the water dimer up to 550 cm −1, the same does not hold for the three‐body interactions. Here, we report the first comprehensive spectrum of the water trimer in the frequency region from 70 to 620 cm −1 using helium‐nanodroplet isolation and free‐electron lasers. By comparison to accompanying high‐level quantum calculations, the experimentally observed intermolecular bands can be assigned. The transition frequencies of the degenerate translation, the degenerate in‐plane and the non‐degenerate out‐of‐plane libration, as well as additional bands of the out‐of‐plane librational mode are reported for the first time. These provide a benchmark for state‐of‐the‐art water potentials and dipole‐moment surfaces, especially with respect to three‐body interactions. Abstract : On the count of three : The first comprehensive spectrum of the water trimer in the frequency region from 70 to 620 cm −1 is reported. The assignments provide a benchmark for state‐of‐the‐art water potentials and dipole‐moment surfaces, especially with respect to three‐body interactions.