Molecular Density Measurements Using Tunable Semiconductor Lasers in a Supersonic Flow

Abstract

Tunable semiconductor lasers were used to probe flow-cooled UF6 molecules in a supersonic nozzle expansion. The number density obtainable and condensation characteristics were determined.

On the Synthesis and Chemical Behaviour of the Elusive Bis(hydrosulfido)‐Bridged Dinuclear Rhodium(I) Complexes [{Rh(μ‐SH)(CO)(PR3)}2]

“…Simultaneous energy and momentum conservation in such collisions can be accommodated by dimer rotation 19. This two‐body encounter theory increases equilibrium dimer populations and formation rates by orders of magnitude compared with a three‐body theory, in agreement with observations 18, 22, 23. It explains why UF 6 /G mixtures experience dimer formation much earlier during supersonic jet expansion in self‐cooling jets than what would be expected on the basis of a three‐body theory.…”

“…This was because prevailing theory demanded that three‐body collisions were necessary 20. However, published measurements by Kim et al at Los Alamos22 and by Human in South‐Africa23 showed that the onset of UF 6 dimer formation in supersonic free jets started much sooner during supersonic expansions than expected. The same phenomenon had been observed earlier for supersonic expansions of SF 6 and other gases,18 but dimer formation in supersonic expansions of UF 6 had theretofore been avoided in MLIS experiments to preserve a sharp absorption spectrum 24, 25…”