Stability of the Hydrogen Trioxy Radical via Infrared Action Spectroscopy
作者:Craig Murray、Erika L. Derro、Timothy D. Sechler、Marsha I. Lester
DOI:10.1021/jp071473w
日期:2007.6.1
The hydrogen trioxy radical (HO3) has been proposed as an intermediate in several important chemical reactions and relaxation processes involving OH in the atmosphere. In this work, the gas-phase infrared action spectrum of HO3 is obtained in the OH overtone region, along with the product state distribution of the OH fragment following dissociation. The highest observed OH product channel sets an upper limit for the HO-O-2 binding energy of 6.12 kcal mol(-1). The experimental stability of HO3 and derived equilibrium constant imply that up to 66% of atmospheric OH may be converted into HO3 in the tropopause region.
Infrared Action Spectroscopy of the OD Stretch Fundamental and Overtone Transitions of the DOOO Radical
作者:Erika L. Derro、Timothy D. Sechler、Craig Murray、Marsha I. Lester
DOI:10.1021/jp801232a
日期:2008.10.2
The DOOO radical has been produced by three-body association between OD and 02 in a supersonic free-jet expansion and investigated using action spectroscopy, an IR-UV double-resonance technique. Partially rotationally structured bands observed at 2635.06 and 5182.42 cm(-1) are assigned to the OD stretch fundamental (V-OD) and overtone (2V(OD)), respectively, of the trans-DOOO radical. Unstructured bands observed in both spectral regions are assigned to cis-DOOO. Nascent OD X-2 Pi product state distributions following vibrational predissociation appear to be nearly statistical with respect to the degree of rotational excitation, but display a marked propensity for Pi(A') A-doublets, which is interpreted as a signature of a planar dissociation. The energetically highest open OD X-2 Pi product channel implies an upper limit dissociation energy Do <= 1856 cm(-1) or 5.31 kcal mol(-1). This value allows refinement of the upper limit D-0 of the atmospherically important HOOO isotopomer, suggesting that it is marginally less stable than previously thought.