Journal
JOURNAL OF PHYSICAL CHEMISTRY A
Volume 118, Issue 35, Pages 7590-7597Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jp504139j
Keywords
-
Funding
- National Science Foundation American Competitiveness in Chemistry Fellowship [CHE-1137404]
- NSF Center for Aerosol Impacts on Climate and the Environment
- National Science Foundation [CHE-1213634, CNS 08-21132]
- U.S. Department of Defense under a National Defense Science and Engineering Graduate Fellowship
- Air Force Office of Scientific Research (AFOSR) chemical dynamics program [FA9550-13-1-0007]
- Chemistry Division of the National Science Foundation [CHE-1213347]
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [1213347] Funding Source: National Science Foundation
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [1213634] Funding Source: National Science Foundation
Ask authors/readers for more resources
Vibrational predissociation spectra of D2-tagged Mg2+OH-(H2O)(n=1-6) and Ca2+OH-(H2O)(n=1-5) clusters are reported to explore how the M2+OH- contact ion pairs respond to stepwise formation of the first hydration shell. In both cases, the hydroxide stretching frequency is found to red-shift strongly starting with addition of the third water molecule, quickly becoming indistinguishable from nonbonded OH groups associated with solvent water molecules by n = 5. A remarkably broad feature centered around 3200 cm(-1) and spanning up to similar to 1000 cm(-1) appears for the n >= 4 clusters that we assign to a single-donor ionic hydrogen bond between a proximal first solvent shell water molecule and the embedded hydroxide ion. The extreme broadening is rationalized with a theoretical model that evaluates the range of local OH stretching frequencies predicted for the heavy particle configurations available in the zero-point vibrational wave function describing the low-frequency modes. The implication of this treatment is that extreme broadening in the vibrational spectrum need not arise from thermal fluctuations in the ion ensemble, but can rather reflect combination bands based on the OH stretching fundamental that involve many quanta of low-frequency modes whose displacements strongly modulate the OH stretching frequency.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available