ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The complex many-line systems observed at around 1850 A(ring) from discharges containing H2O or D2O [A. Michel, Z. Naturforsch. 12a, 887 (1957); P. Felenbok and J. Czarny, Annu. Astrophys. 27, 244 (1964)] have been reinvestigated at high resolution in the emission from supersonic jet expansions. Mixtures of He with D2O produce a conspicuous progression of red shaded bands that overlap the many-line spectra but have not been reported before. The new transitions originate at large internuclear distance in a single 2Π vibronic level of OD at 88 294 cm−1 above the minimum of the ground-state potential, and they end on high vibrational levels, v‘=13,...,18, of X 2Π. Term values and spectroscopic parameters for the initial and final states have been determined; the upper state, labeled C'2Π, is inverted with a spin-orbit interaction that is close to the A value of X 2Πi. Analogous bands of OH have not been detected, and in contrast with the many-line emissions of both isotopes which persist in the presence of Ar as well as of He and in discharges through pure water vapor, the new C'2Π→X 2Π bands of OD appear only in mixtures with He. Guided by ab initio calculations for the 2Π excited states of OH [E. F. van Dishoeck and A. Dalgarno, J. Chem. Phys. 79, 873 (1983)], the interpretation of the experimental results concludes that all of the observed emission at around 1850 A(ring) originates in a group of more or less strongly mixed 2Π levels which reflect the radiative properties and excitation characteristics of two interacting stable diabatic states and which escape predissociation by a repulsive third 2Π state.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.462187
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