Gas phase vibrational spectroscopy of the protonated water pentamer: the role of isomers and nuclear quantum effects.
Phys Chem Chem Phys
; 18(38): 26743-26754, 2016 Sep 29.
Article
em En
| MEDLINE
| ID: mdl-27722600
ABSTRACT
We use cryogenic ion trap vibrational spectroscopy to study the structure of the protonated water pentamer, H+(H2O)5, and its fully deuterated isotopologue, D+(D2O)5, over nearly the complete infrared spectral range (220-4000 cm-1) in combination with harmonic and anharmonic electronic structure calculations as well as RRKM modelling. Isomer-selective IR-IR double-resonance measurements on the H+(H2O)5 isotopologue establish that the spectrum is due to a single constitutional isomer, thus discounting the recent analysis of the band pattern in the context of two isomers based on AIMD simulations ãW. Kulig and N. Agmon, Phys. Chem. Chem. Phys., 2014, 16, 4933-4941ã. The evolution of the persistent bands in the D+(D2O)5 cluster allows the assignment of the fundamentals in the spectra of both isotopologues, and the simpler pattern displayed by the heavier isotopologue is consistent with the calculated spectrum for the branched, Eigen-based structure originally proposed ãJ.-C. Jiang, et al., J. Am. Chem. Soc., 2000, 122, 1398-1410ã. This pattern persists in the vibrational spectra of H+(H2O)5 in the temperature range from 13 K up to 250 K. The present study also underscores the importance of considering nuclear quantum effects in predicting the kinetic stability of these isomers at low temperatures.
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01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Phys Chem Chem Phys
Assunto da revista:
BIOFISICA
/
QUIMICA
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Alemanha