Collision energy dependence of the cross sections for the electronic excitation transfer reactions: Rg(/sup 3/P/sub 0,2/)+N/sub 2/(X /sup 1/. sigma. /sub g/). -->. Rg(/sup 1/S/sub 0/) +N/sub 2/(C /sup 3/Pi/sub u/) (Rg = Ar, Kr)
The collision energy dependence of the integral cross sections for the title reactions were determined using crossed molecular beams and time-of-flight energy selection techniques. Applying arc-heated rare gas atom beams, the relative collision energies of metastable Ar(/sup 3/P/sub 0,2/) and Kr(/sup 3/P/sub 0,2/) atoms were selected between 0.4 and 2.5 eV for Ar(/sup 3/P/sub 0,2/)+N/sub 2/, and 0.6 and 1.7 eV for Kr(/sup 3/P/sub 0,2/)+N/sub 2/ systems. The negative energy dependence of the cross sections for the prototype reaction Ar(/sup 3/P/sub 0,2/)+N/sub 2/ agrees well with the results of Parr and Martin in the overlapped energy range (0.4--0.8 eV). The absolute cross sections were determined by normalizing our cross sections to the ones of Parr and Martin. As to the endoergic Kr(/sup 3/P/sub 0,2/)+N/sub 2/ reaction, the product fluorescence from N/sub 2/(C /sup 3/Pi/sub u/--B /sup 3/Pi/sub g/) was also observed. The total cross section for this reaction exhibits a steep increase near the threshold for each component state (..delta..H(/sup 3/P/sub 0/) = 0.47 and ..delta..H(/sup 3/P/sub 2/) = 1.12 eV) and then tends to level off. Assuming the component ratio Kr(/sup 3/P/sub 2/)/Kr(/sup 3/P/sub 0/) to be statistical in the arc-heated beams, the cross section for each reaction was evaluated by convolution analysis. The post-threshold cross sections for these processes are one to two orders of magnitude smaller than those obtained for Ar(/sup 3/P/sub 0,2/)+N/sub 2/ reaction. The higher reactivity found for Kr(/sup 3/P/sub 2/) than for Kr(/sup 3/P/sub 0/) is consistent with the quenching rates of Ar(/sup 3/P/sub 0/) and Ar(/sup 3/P/sub 2/) by N/sub 2/ obtained by Piper, Velazco, and Setser (J. Chem. Phys. 59, 3323 (1973)).
- Research Organization:
- Institute for Molecular Science, Okazaki 444, Japan
- OSTI ID:
- 6007989
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 84:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARGON
ATOM-MOLECULE COLLISIONS
ENERGY TRANSFER
DE-EXCITATION
KRYPTON
NITROGEN
ATOMIC BEAMS
CROSS SECTIONS
ENERGY DEPENDENCE
MOLECULAR BEAMS
RADIATIONLESS DECAY
ATOM COLLISIONS
BEAMS
COLLISIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
FLUIDS
GASES
MOLECULE COLLISIONS
NONMETALS
RARE GASES
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena