Cross sections for collisional excitation of interstellar formaldehyde.
Abstract
The cross sections for excitation of H2CO in collisions with H2 have been calculated in a quantum mechanical, closecoupling form. The Kohn variational method, adapted for multi channel scattering, was used to convert the system of coupled differential equations to a set of coupled algebraic equations. The effect of including close coupling is to increase the cross sections for excitation to the lower state of each doublet, relative to the cross sections for excitation to the upper state. This fact suggests that earlier quantum mechanical calculations differed from classical calculations because they neglected the coupling of states during the collision. These results lend credence to the collisional model for explaining the observations of anomalous absorption in H2CO at 6cm and 2cm wavelengths. Subject headings: atomic and molecular processes molecules, interstellar
 Publication:

The Astrophysical Journal
 Pub Date:
 October 1975
 DOI:
 10.1086/153865
 Bibcode:
 1975ApJ...201..112E
 Keywords:

 Formaldehyde;
 Interstellar Matter;
 Molecular Excitation;
 Particle Collisions;
 Scattering Cross Sections;
 Absorption Cross Sections;
 Born Approximation;
 Calculus Of Variations;
 Collision Parameters;
 Differential Equations;
 Mathematical Models;
 Numerical Analysis;
 Quantum Mechanics;
 Astrophysics