Abstract

In many experiments involving molecular beams for fundamental studies of e.g. chemical reactions in crossed beams [1,2], so called seeded beams are used. In such a beam a few percent of the desired molecule is mixed in an excess of light driver gas. This accelerates the heavier seed molecules, and also cools the translational, rotational, and vibrational degrees of freedom of the molecules. The translational acceleration and simultaneous cooling in the beam can be studied by molecular beam techniques coupled to mass spectroscopy, like rapid mechanical chopping and molecular time-of-flight measurements. The rotational and vibrational temperatures are much harder to determined in an ordinary molecular apparatus, and some optical spectroscopic method is usually needed [3,4,5].

© 1987 Optical Society of America