Single-field slice-imaging with a movable repeller: Photodissociation of N{sub 2}O from a hot nozzle

Journal Article · Thu Aug 07 04:00:00 EDT 2014 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4891469· OSTI ID:22419988

Harding, Dan J.; Neugebohren, J.; Grütter, M.; Schmidt-May, A. F.; Auerbach, D. J.

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, Journal Name: Journal of Chemical Physics Journal Issue: 5 Vol. 141; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
CROSS SECTIONS
DISSOCIATION
DISSOCIATION ENERGY
ELECTRIC UTILITIES
ENERGY TRANSFER
EV RANGE
EXCITATION
MOLECULAR BEAMS
NITROUS OXIDE
NOZZLES
PHOTOIONIZATION
PHOTOLYSIS
VIBRATIONAL STATES