Photofragment imaging: The two-photon dissociation of methane
- Sandia National Labs., Livermore, CA (United States)
- Stanford Univ., CA (United States)
The photochemistry of methane is important in many fields of research. Besides being of fundamental importance to the understanding of photochemistry it is the major production mechanism for small organic radicals in the early atmosphere of earth, the atmosphere of Jupiter and in the interstellar medium. Until now the prevailing wisdom, as reflected in models, was that upon adsorption of an ultraviolet photon CH{sub 4} dissociated into CH{sub 2} + H{sub 2}. We use the photofragment imaging technique to measure the product state distributions, branching ratios and velocity distributions following dissociation of methane having about 11 eV of energy. In our experiment a single laser pulse dissociates the methane and ionizes a fragment (H atom or H{sub 2} molecule). The velocity of the fragment is measured using ion imaging techniques. The methane is excited with either a VUV photon, at 121 nm, in order to measure the velocity distribution of the H atoms or dissociated via two photons near 205 nm to state-selectively measure the velocity distribution of the H{sub 2} molecules formed. In contradiction to existing models, we find both H atoms and H{sub 2} molecules am formed in the initial dissociation step with H atoms being predominant.
- OSTI ID:
- 370842
- Report Number(s):
- CONF-960376--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photofragment imaging: the 205-nm photodissociation of CH3Br and CD3Br*
Investigation of acetyl chloride photodissociation by photofragment imaging