Electronic Resource
College Park, Md.
:
American Institute of Physics (AIP)
The Journal of Chemical Physics
116 (2002), S. 4955-4961
ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Vibrationally mediated photodissociation action spectroscopy provides rotation-vibration spectra of jet-cooled ammonia in the 2.3 μm and 3.0 μm regions by detecting the emission of electronically excited NH2(A˜ 2A1) produced by the photodissociation of the vibrationally excited molecules. Vibrational excitation changes the relative photofragmentation yield of NH2(A˜ 2A1) markedly. Isoenergetic photolysis of ammonia molecules with one quantum of antisymmetric N–H stretching excitation (ν3) or two quanta of bend (2ν4) yields three times more excited state NH2(A˜ 2A1) than photolysis of NH3 with a quantum of symmetric N–H stretch excitation (ν1). By contrast, the relative yield is insensitive to initial vibrational excitation of the combination bands ν1+ν2 and ν2+ν3 that contain the umbrella (inversion) motion ν2. The vibrational mode dependence of the NH2(A˜ 2A1) photofragment yield arises from either enhanced Franck–Condon factors for electronic excitation or from an increased probability for the competing nonadiabatic dissociation to form the ground state NH2(X˜ 2B1) product. © 2002 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1450550
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