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Persistent URL http://purl.org/net/epubs/work/37895
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Record Id 37895
Title Dynamics of the Hydrogen Exchange Reaction using the Photoloc Technique
Abstract The dynamics of the H + D2 exchange reaction has been studied experimentally using laser, velocity- sensitive time-of-flight (TOF) methods. Chemical reaction is initiated by laser photolysis of a suitable HX precursor resulting in a collision energy spread of 50 meV. HD(v ', J') products are detected via (2+1) resonance-enhanced multiphoton ionization (REMPI) inside a Wiley-McLaren time-of-flight spectrometer. Integral cross section measurements are performed by measuring the total ion yield into different product rovibrational states. In addition, core extraction of the ion packet prior to detection allows an unambiguous inversion of the laboratory product velocity distribution into a corresponding center-of-mass differential cross section with an angular resolution ranging from 3° for backward to 15° for forward scattering. The measured rotational distributions for the HD(v' = 1, 2, J) vibrational manifolds at collision energies ca. 1.6 eV agree closely with quasiclassical trajectory calculations. These distributions are colder than the "prior'' limit indicating that other constraints besides energy conservation are dictating energy disposal into the rotational degree of Freedom of the diatomic product. Further insight into the dynamics of this reaction is given by the differential cross section measurements into particular HD(v' = 1, J') and HD(v' = 2, J') quantum states. In each vibrational manifold, the product angular distributions are completely back ward scattered for low- J' states, and they shift toward side scattering as the rotational excitation of the product increases. Experimental data at a lower angular resolution for HD(v' = 3, J' ) also show a similar trend in the angular distributions. The differential cross section data can be qualitatively explained by invoking a line- of-centers with nearly elastic specular scattering model which links the most probable scattering angle for a given HD(v', J') product state with initial impact parameter. Within the framework of this model, the angular distributions for HD(v' = 1, J ') and HD(v' = 2, J') only show differences that can be attributed to a smaller hard-sphere radius leading to the more vibrationally excited product.
Organisation CCLRC , ISIS , ISIS-GEN
Keywords Physics , Chemistry , ISIS 2007
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Language English (EN)
Type Details URI(s) Local file(s) Year
Thesis PhD, Stanford University, 2000. http://adsabs.har…/2000PhDT........19F PhD_Thesis_FFA_2000.ps 2000