Mid-infrared signatures of hydroxyl containing water clusters: Infrared laser Stark spectroscopy of OH–H{sub 2}O and OH(D{sub 2}O){sub n} (n = 1-3)

Journal Article · Wed Oct 28 04:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4933432· OSTI ID:22493153

Hernandez, Federico J. ^[1]; Brice, Joseph T.; Leavitt, Christopher M.; Liang, Tao; Raston, Paul L. ^[2]; Pino, Gustavo A. ^[3]

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1. Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States)
2. Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807 (United States)
3. INFIQC, Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón, X5000HUA Córdoba (Argentina)

Small water clusters containing a single hydroxyl radical are synthesized in liquid helium droplets. The OH–H{sub 2}O and OH(D{sub 2}O){sub n} clusters (n = 1-3) are probed with infrared laser spectroscopy in the vicinity of the hydroxyl radical OH stretch vibration. Experimental band origins are qualitatively consistent with ab initio calculations of the global minimum structures; however, frequency shifts from isolated OH are significantly over-predicted by both B3LYP and MP2 methods. An effective Hamiltonian that accounts for partial quenching of electronic angular momentum is used to analyze Stark spectra of the OH–H{sub 2}O and OH–D{sub 2}O binary complexes, revealing a 3.70(5) D permanent electric dipole moment. Computations of the dipole moment are in good agreement with experiment when large-amplitude vibrational averaging is taken into account. Polarization spectroscopy is employed to characterize two vibrational bands assigned to OH(D{sub 2}O){sub 2}, revealing two nearly isoenergetic cyclic isomers that differ in the orientation of the non-hydrogen-bonded deuterium atoms relative to the plane of the three oxygen atoms. The dipole moments for these clusters are determined to be approximately 2.5 and 1.8 D for “up-up” and “up-down” structures, respectively. Hydroxyl stretching bands of larger clusters containing three or more D{sub 2}O molecules are observed shifted approximately 300 cm{sup −1} to the red of the isolated OH radical. Pressure dependence studies and ab initio calculations imply the presence of multiple cyclic isomers of OH(D{sub 2}O){sub 3}.

• OSTI ID: 22493153
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 16 Vol. 143; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANGULAR MOMENTUM
APPROXIMATIONS
DEUTERIUM
DROPLETS
ELECTRIC DIPOLE MOMENTS
HAMILTONIANS
HEAVY WATER
HELIUM
HYDROGEN
HYDROXIDES
HYDROXYL RADICALS
ISOMERS
LASER SPECTROSCOPY
LASERS
LIQUIDS
MOLECULES
OXYGEN
PRESSURE DEPENDENCE
SPECTRA
VIBRATIONAL STATES