Title: Influence of Collisions upon Population of Hyperfine States in Hydrogen.
Abstract: view Abstract Citations (200) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Influence of Collisions upon Population of Hyperfine States in Hydrogen. Purcell, Edward M. ; Field, George B. Abstract In a collision between two hydrogen atoms in their ground states, the electron spins may exchange Such exchanges affect the relative populations of the hyperfine levels and are therefore important in determining the rate of 21-cm transitions in an assembly of atoms undergoing collision A cross-section is computed for electron exchange over a range of gas kinetic temperatures, and the competition between collisions and radiation in establishing the hyperfine populations is analyzed The results are applied to typical situations encountered in 21-cm radio astronomy Publication: The Astrophysical Journal Pub Date: November 1956 DOI: 10.1086/146259 Bibcode: 1956ApJ...124..542P full text sources ADS |