@article {346,
title = {Collision-induced alignment of NO+ drifting in argon: Calculated distribution functions and microscopic quadrupole alignment parameters},
journal = {Journal of Chemical Physics},
volume = {116},
number = {15},
year = {2002},
note = {ISI Document Delivery No.: 537PGTimes Cited: 5Cited Reference Count: 32},
month = {Apr},
pages = {6605-6613},
type = {Article},
abstract = {Molecular dynamics simulations of NO+ drifting in argon are presented. In this system, the ion-bath gas mass ratio is close to but less than unity, thus increasing the importance of inelastic collisions. Strong velocity-angular momentum coupling is found, and in particular the quadrupolar alignment parameter as a function of the velocity parallel with the field takes on, with decreasing velocities, values that start as negative, become positive, and subsequently decay toward negative. To the best of our knowledge, this is the first report of the decay of this alignment towards negative values at the low end of the velocity distribution. The accuracy of an approximate distribution function [R. Baranowski and M. Thachuk, Phys. Rev. A 63, 032503 (2001)] is also examined in detail. It is found to give results that are generally qualitatively correct, and for many properties, semiquantitatively correct as well. The agreement, however, is not as good as that found for systems with ion-bath gas ratios greatly exceeding unity. (C) 2002 American Institute of Physics.},
keywords = {AR-NO+, ATOMIC GASES, EXPANSIONS, ION MOBILITY SPECTROMETRY, MOLECULAR-DYNAMICS, ROTATIONAL ALIGNMENT, SCATTERING, SUPERSONIC, SURFACES, TRANSPORT, VELOCITY DISTRIBUTIONS},
isbn = {0021-9606},
url = {://000174767200023},
author = {Chen, X. and Araghi, R. and Baranowski, R. and Thachuk, M.}
}
@article {5007,
title = {Analysis of physical observables and approximate distribution functions for drifting linear ions},
journal = {Physical Review A},
volume = {64},
number = {6},
year = {2001},
note = {ISI Document Delivery No.: 500CKTimes Cited: 3Cited Reference Count: 22},
month = {Dec},
pages = {13},
type = {Article},
abstract = {The accuracy of two recently proposed approximate distribution functions for drifting linear ions [R. Baranowski and M. Thachuk, Phys. Rev. A 63, 032503 (2001) is tested at a number of levels of microscopic detail. Through formal mathematical manipulations. low-order expressions are derived for a number of physical observables, including the angular momentum dependence of the drift velocity, and parallel and perpendicular translational temperatures. as well as the dependence of the quadrupolar alignment parameter on the parallel and perpendicular velocity components. Finally, comparisons are made between the approximate forms and basis set expansions of the distribution function utilized in formal solutions of the Boltzmann equation, with the goal of suggesting general features of these basis sets that might help improve convergence.},
keywords = {ATOMIC GASES, COLLISIONAL ALIGNMENT, DYNAMICS, MOLECULES, ROTATIONAL ALIGNMENT, SCATTERING, SUPERSONIC EXPANSIONS, SYSTEMS, TRANSPORT-COEFFICIENTS, VELOCITY DISTRIBUTIONS},
isbn = {1050-2947},
url = {://000172608200050},
author = {Baranowski, R. and Thachuk, M.}
}
@article {5008,
title = {Simple analytic form for the velocity-angular-momentum distribution function of drifting linear ions},
journal = {Physical Review A},
volume = {63},
number = {3},
year = {2001},
note = {ISI Document Delivery No.: 408HPTimes Cited: 6Cited Reference Count: 21},
month = {Mar},
pages = {12},
type = {Article},
abstract = {A simple analytic form is presented for the full velocity-angular-momentum distribution function for gasphase linear ions drifting in an atomic bath gas under a constant external electric field. Predictions of temperatures, drift velocities, and alignment parameters from this form are compared in detail against molecular-dynamics calculations for NO+ drifting in helium. The form is accurate, compact, and based upon a physically motivated expansion. In essence, simple Maxwellian-like functions are generalized by allowing appropriate temperatures to become functions of velocity and rotational ang;lar momentum. Over a wide range of reduced field strengths, including the equilibrium state, this form is able to account accurately for many properties at a microscopic level with only a few adjustable parameters.},
keywords = {ATOMIC GASES, COLLISIONAL ALIGNMENT, DYNAMICS, MOLECULES, ROTATIONAL ALIGNMENT, SCATTERING, SUPERSONIC EXPANSIONS, SWARM, TRANSPORT-COEFFICIENTS},
isbn = {1050-2947},
url = {://000167321000041},
author = {Baranowski, R. and Thachuk, M.}
}
@article {4468,
title = {Molecular-dynamics study of rotational alignment of NO+ drifting in helium-velocity and angular momentum distribution functions},
journal = {Journal of Chemical Physics},
volume = {111},
number = {22},
year = {1999},
note = {ISI Document Delivery No.: 258RKTimes Cited: 8Cited Reference Count: 27},
month = {Dec},
pages = {10061-10068},
type = {Article},
abstract = {Collision-induced rotational alignment of NO+ ions drifting in a helium buffer gas is studied with molecular dynamics using the ab initio potential surface of S. K. Pogrebnya [Int. J. Mass Spectrom. Ion Proc. 149/150, 207 (1995)], obtained via a coupled-cluster singles-doubles approximation. We examine average translational and rotational temperatures, velocity and angular momentum distributions, and the dependence of these quantities on the applied electric field. The distributions show that angular momentum is preferentially aligned perpendicular to the electric field vector. We investigate the mechanism of this alignment through a multipolar moment expansion, and propose and demonstrate the accuracy of a bi-Maxwellian analytic form for describing the angular momentum distribution. (C) 1999 American Institute of Physics. [S0021-9606(99)00546-2].},
keywords = {ATOMIC GASES, HE, IONS, KINETIC-THEORY, MOBILITIES, NA+, TRANSPORT-COEFFICIENTS, TUBE EXPERIMENTS},
isbn = {0021-9606},
url = {://000083852700018},
author = {Baranowski, R. and Thachuk, M.}
}