Rotational excitation of N/sub 2/ by electron impact: 1-4 eV
Rotational and rotational-vibrational (v = 0 ..-->.. 1) excitation in N/sub 2/ have been studied with a crossed-beam electron-impact apparatus. In the energy range 1-4 eV, the elastic and vibrational energy-loss peaks show large rotational broadening compared with the apparatus profile (full width at half-maximum, 18 meV). The branching ratios for rotational transitions with ..delta..j = 0, +- 2, +- 4 are obtained with a line-shape analysis applied to the energy-loss profiles. The results for rotational-vibrational excitation at 2.27 eV and scattering angles 30-90/sup 0/ are in good agreement with the calculations using the resonant d..pi.. waves and the rotational impulse approximation. The corresponding results for pure rotational excitation show that the branches with ..delta..j = +- 2 and +- 4 are predominantly excited via resonances, while the branch with ..delta..j = 0 contains a large contribution from direct scattering. The absolute rotational cross sections for ..delta..j = +- 4 are measured; they exhibit a large magnitude (10/sup -16/ cm/sup 2/) and peak and valley structures in the 1-4 eV range, reminiscent of well-known resonant vibrational excitation. The energy dependence and the absolute magnitude of the rotational cross sections for ..delta..j = +- 4 can be understood in terms of a ''boomerang'' calculation. A comparison of the experiment with the relevant theoretical calculations is made.
- Research Organization:
- Department of Engineering and Applied Science, Mason Laboratory, Yale University, New Haven, Connecticut 06520
- OSTI ID:
- 5201727
- Journal Information:
- Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 17:2; ISSN PLRAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 01-10
EXCITATION
EXCITED STATES
FLUIDS
MOLECULE COLLISIONS
NITROGEN
NONMETALS
ROTATIONAL STATES