Single-field slice-imaging with a movable repeller: Photodissociation of N{sub 2}O from a hot nozzle
We present a new photo-fragment imaging spectrometer, which employs a movable repeller in a single field imaging geometry. This innovation offers two principal advantages. First, the optimal fields for velocity mapping can easily be achieved even using a large molecular beam diameter (5 mm); the velocity resolution (better than 1%) is sufficient to easily resolve photo-electron recoil in (2 + 1) resonant enhanced multiphoton ionization of N{sub 2} photoproducts from N{sub 2}O or from molecular beam cooled N{sub 2}. Second, rapid changes between spatial imaging, velocity mapping, and slice imaging are straightforward. We demonstrate this technique's utility in a re-investigation of the photodissociation of N{sub 2}O. Using a hot nozzle, we observe slice images that strongly depend on nozzle temperature. Our data indicate that in our hot nozzle expansion, only pure bending vibrations – (0, v{sub 2}, 0) – are populated, as vibrational excitation in pure stretching or bend-stretch combination modes are quenched via collisional near-resonant V-V energy transfer to the nearly degenerate bending states. We derive vibrationally state resolved absolute absorption cross-sections for (0, v{sub 2} ≤ 7, 0). These results agree well with previous work at lower values of v{sub 2}, both experimental and theoretical. The dissociation energy of N{sub 2}O with respect to the O({sup 1}D) + N{sub 2} + Σ{sup +}{sub g} asymptote was determined to be 3.65 ± 0.02 eV.
- OSTI ID:
- 22419988
- Journal Information:
- Journal of Chemical Physics, Vol. 141, Issue 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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