Rotational-State and Velocity-Subgroup Dependence of the Rotational Alignment of N2+ Drifted in He

Published

April 1, 2001

Author(s)

E B. Anthony, V M. Bierbaum, S R. Leone

Abstract

Experimental results are presented for the rotational alignment of- N₂⁺(Ņ=O) as a function of both rotational state and component Dopplervelocity. A single-frequency ring dye laser is used to probe the alignment of N₂⁺ drifted in helium in a flow-drift apparatus by the technique of polarized laser-induced fluorescence. The collision-induced quadrupole rotational alignment parameter A_o⁽²⁾ is determined as a function of the field direction component of sub-Doppler laboratory velocity at a fixed field strength of 12 Td for five rotational states. A dramatic difference in velocity-selected alignment as a function of rotational state is observed, with the higher rotational states exhibiting a greater degree of alignment than the lower rotational states. Additionally, for sufficiently low rotational state (J = 11.5), A_O^u(2) changes sign across the Doppler profile, a behavior that has not previously been reported in the literature. A companion theoretical paper presents molecular dynamics calculations that are in excellent agreement with these experimental observations.

Citation

Journal of Chemical Physics

Volume

114

Issue

No. 15

Pub Type

Journals

Keywords

alignment mobility, ion, rotation

Citation

Anthony, E. , Bierbaum, V. and Leone, S. (2001), Rotational-State and Velocity-Subgroup Dependence of the Rotational Alignment of N₂⁺ Drifted in He, Journal of Chemical Physics (Accessed October 27, 2025)