- Laser excited fluorescence study of reactions of excited Ca and Sr with water and alcohols: Product selectivity and energy disposal
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Reactions of the metastable 3PJ0 states of Ca and Sr in atomic beams with H2O, D2O, and CH3OH yielding ground electronic state products have been observed by laser excited fluorescence of MOH, MOD, and MOCH3. The water reactions favor metal hydroxide Droductsjvhile methanol reactions favor methoxides. For SrOH product, spectral simulation of the B 2Σ+ -X 2S+ transition based on coupled harmonic-oscillator Franck-Condon factors was used to determine crude vibrational energy distributions in the bending and metal-stretching modes, and simulation of a higher resolution scan of excitation of the ground vibrational level gave some information about the rotational energy distribution in that level. While excitation of metal stretching and rotation were considerable and not too far from the predictions of a prior model, bending was significantly colder. Limited spectroscopic constants and severe spectral congestion have precluded other successful simulations.
- Oberlander,Parson
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- Observation of several new electronic transitions of the SrOH free radical
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We report four new electronic transitions of the SrOH free radical, the C 2Π-X 2Σ+, D 2Σ+-X 2Σ+, E 2Σ+-X 2Σ+, and F 2Π-X 2Σ+ transitions. SrOH was prepared in a supersonic jet by laser ablation and spectra were recorded using laser-induced fluorescence. The C 2Π-X 2Σ+ excitation spectrum shows complex vibronic structure which is attributed, at least in part, to Renner-Teller activity in the excited electronic state. This is supported by dispersed fluorescence spectra which show substantial bending mode activity in the emission from several different excited vibronic levels. It is suggested that the prominence of nominally forbidden vibrational features arises from a large change in permanent electric dipole moment between the X and C states. In turn, this suggests that the C 2Π state of SrOH is the analogue of the reverse-polarized 2 Π states known for the alkaline-earth monohalides, i.e., the highest occupied π orbital points towards the O atom. The D 2Σ+-X 2Σ+, E 2Σ+-X 2Σ+, and F 2Π-X 2Σ+ spectra are much simpler than the C-X system, being dominated by regular structure in the Sr-O stretching vibration.
- Beardah, Matthew S.,Ellis, Andrew M.
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- ELECTRONIC MATRIX ISOLATION SPECTROSCOPIC STUDIES OF THE GROUP IIA METAL-WATER PHOTOCHEMISTRY.
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Results are reported of an investigation of the electronic structures of the Group IIA metal atom hydration reaction intermediates (M. . . OH//2 adducts) and their subsequent photolysis products (HMOH and MOH). For the adduct, the metal-water interaction is sufficiently strong so as to perturb significantly the electronic structure of the metal atom, which results in a unique band structure for the adduct that is red-shifted from the metal atomic resonance transition. Selective photolysis studies are conducted to assist in deconvoluting the complex band structure of the adduct. Molecular orbital theory is invoked to interpret the nature of the ground and excited states of the adduct.
- Douglas,Hauge,Margrave
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p. 201 - 235
(2008/10/08)
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- INFRARED MATRIX ISOLATION STUDIES OF THE INTERACTIONS OF Mg, Ca, Sr, AND Ba ATOMS AND SMALL CLUSTERS WITH WATER.
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Mg, Ca, Sr, and Ba metal atoms react with water to form M**. **. **. OH//2 adducts on cocondensation at 15 K in excess argon. Adduct formation is evidenced by a red shift in the water nu //2 bending mode frequency and ranges from approximately 15 cm** minus **1 for Mg to approximately 30 cm** minus **1 for Ca, Sr, and Ba. Subsequent photolysis of the adducts results in oxidative insertion reactions to form HMOH molecules. At higher magnesium metal concentrations, Mg//2**. **. **. OH//2 and Mg//x**. **. **. OH//2, x greater than equivalent to 3, adducts are observed. Sequential reactions between two metal atoms and one water molecule produce the HMOMH species in the case of Mg and Ca. Reaction between one Ca metal atom and two water molecules produces the Ca(OH)//2 molecule.
- Kauffman,Hauge,Margrave
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