Rotational and electronic relaxation in pulsed supersonic beams of NO seeded in He and Ar

Journal Article · Mon Oct 01 04:00:00 EDT 1984 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.448018· OSTI ID:6398985

Zacharias, H; Loy, M M.T.; Roland, P A; Sudbo, A S

Resonantly enhanced two-photon ionization has been used to obtain detailed information about the rotational and electronic relaxation in pulsed supersonic expansions of nitric oxide seeded in helium and argon. Due to the sensitivity of the method we were able to measure rotational distributions up to high quantum numbers J''>24.5. Measurements were made for stagnation pressures ( p/sub 0/) and nozzle diameters (d) in the range 0.44< or =p/sub 0/d< or =22 (Torr cm) for NO/Ar beams, and 0.88< or =p/sub 0/d< or =36 (Torr cm) for NO/He beams. In general non-Boltzmann rotational population distributions were observed. Furthermore, we found that for NO/He beams, the two electronic substates /sup 2/Pi/sub 1//sub ///sub 2/ and /sup 2/Pi/sub 3//sub ///sub 2/ of NO were not in local equilibrium. These observations can be understood in terms of a simple model using state-to-state collision cross sections combined with the empirical hydrodynamic equations to describe the isentropic expansions.

• Research Organization: IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598
• OSTI ID: 6398985
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 81:7; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640301* -- Atomic
Molecular &amp; Chemical Physics-- Beams &amp; their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
CHALCOGENIDES
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
FLUID FLOW
JETS
MOLECULAR BEAMS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
RELAXATION
ROTATIONAL STATES
SUPERSONIC FLOW