Laser Probing of Velocity-Subgroup Dependent Rotational Alignment of N2+ Drifted in He

Published

April 1, 1997

Author(s)

E B. Anthony, W Schade, M J. Bastian, V M. Bierbaum, S R. Leone

Abstract

Results are presented for Doppler-resolved laser-induced fluorescent measurements of collision-induced rotational alignment of N₂⁺(Ņ=0) drifted in He in a drift-tube apparatus. A single-frequency ring dye laser is used to probe the R_-1(N=15) rotational line of the B²Σ_u⁺-X²Σ_g⁺ system both parallel and perpendicular to the drift field at three different field strengths and at several different Doppler-selected velocities. A strong correlation is found between the degree of rotational alignment and the velocity subgroup probed the quadrupole alignment parameters A^0^⁽²⁾ with higher velocity subgroup, up to a maximum value of A^o^⁽²⁾=-0.150(6) for 16 Td at the high-velocity tail. There is evidence that the correlation between alignment and velocity increases with increasing field strength. The mechanisms of the alignment are discussed and these results are attributed primarily to the change in anisotropy of the relative velocity vector distribution of the N₂⁺-He pair with field strength.

Citation

Journal of Chemical Physics

Volume

106

Issue

No. 13

Pub Type

Journals

Keywords

ion transport properties, N₂⁺, rotational alignment

Citation

Anthony, E. , Schade, W. , Bastian, M. , Bierbaum, V. and Leone, S. (1997), Laser Probing of Velocity-Subgroup Dependent Rotational Alignment of N₂⁺ Drifted in He, Journal of Chemical Physics (Accessed October 17, 2025)