Related Experiment Video
Updated: Jun 25, 2026

A Basic Positron Emission Tomography System Constructed to Locate a Radioactive Source in a Bi-dimensional Space
Published on: February 1, 2016
Tensor cross sections and the collisional evolution of state multipoles: OH(X (2)Pi)-Ar
Paul J Dagdigian1, Millard H Alexander
1Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA. pjdagdigian@jhu.edu
Abstract:
By means of a kinetic analysis, we show that the overall rate constant for the collisional loss of orientation or alignment of a rotational level is the sum of the rate constant for elastic depolarization and the sum of the rate constants for all rotationally inelastic transitions out of the level under consideration. An expression for the depolarization cross section is derived in terms of tensor cross sections, and the relationship of depolarization to m-resolved transitions is discussed. We use this formalism in simulations, based on high-quality ab initio potential energy surfaces, of the depolarization of the open-shell molecule OH(X (2)Pi) through collisions with Ar. Good agreement is seen with the results of the two-color polarization spectroscopy experiments of Paterson et al. [J. Chem. Phys. 129, 074304 (2008)]. In addition, we show that the major contribution to elastic collisional depolarization occurs not from weak, glancing collisions but from encounters which probe the inner wall of the potential energy surface.
Related Concept Videos
Mass Analyzers: Common Types
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Tandem Mass Spectrometry
Atomic Nuclei: Magnetic Resonance
2D NMR: Overview of Homonuclear Correlation Techniques
COSY90 is the standard two-dimensional (2D) COSY experiment that...
¹H NMR Signal Multiplicity: Splitting Patterns

