Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Laser Probing of Rotational-State-Dependent Velocity Distributions of N+2 (Ņ= O,J) Drifted in He



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


rotational state-resolved velocity component distribution functions of N+2 (nu=O) drifted in helium are measured in a flow-drift apparatus by the technique of single-frequency laser-induced fluorescence (LIF). A single-mode ring dye laser is used to probe Doppler profiles of various rotational lines in the R-branch of the (Ņ' ,Ņ) =(O,O) band of the B2ς+g system at 390 nm, with the laser propagation direction set either parallel or perpendicular to the drift field. A small but definite (3%) increase in ion mobility with increasing rotational state from J=13.5 to J=22.5 is observed at a fixed field strength of 12 Td Mobilities of J=15.5 measured over the range of 1.5-16 Td yield a Ko(O) of 22.0 cm2V-1s-1 and are in good agreement with earlier arrival-time measurements. Parallel translational temperatures are found to be significantly higher than perpendicular temperatures; a difference of at least 140 K between these temperatures is measured for J=15.5 at 16 Td. No discernible difference between the parallel translational temperatures for different rotational states is observed. There is evidence for a small degree of positive skewness(third central moment) in the parallel velocity component distributions, the first observation of such an effect in a molecular ion-atomic buffer system. Previous results that indicated poor agreement between CO+-He pulsed-field arrival-time and LIF mobilities are discussed: the LIF results were most likely hampered by space-charge effects.
Journal of Chemical Physics
No. 23


Doppler, drift, ion, laser, mobility, velocity


Anthony, E. , Basitan, V. , Bierbaum, V. and Leone, S. (2000), Laser Probing of Rotational-State-Dependent Velocity Distributions of N<sup>+</sup><sub>2</sub> (&#325;= O,J) Drifted in He, Journal of Chemical Physics (Accessed June 25, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created May 31, 2000, Updated October 12, 2021