Miffre A, Jacquey M, Büchner M, Trénec G, Vigué J
Laboratoire Collisions Agrégats Réactivité-IRSAMC, Université Paul Sabatier and CNRS UMR 5589, 118, Route de Narbonne, 31062 Toulouse Cedex, France.
J Chem Phys. 2005 Mar 1;122(9):094308. doi: 10.1063/1.1850897.
Supersonic expansion is a very powerful tool to produce an atomic beam with a well defined velocity and, by seeding a test gas in such an expansion, the energy of the test gas can be transferred, at least partially, to the very-low-temperature carrier gas. The case usually studied is the one of a heavy gas seeded in a light carrier gas and, in this case, the parallel temperature of the seeded gas is always larger than the one of the carrier gas. In the present paper, we study the opposite case which has received less attention: when a light gas is seeded in a heavier carrier gas, the parallel temperature can be substantially lower for the seeded gas than for the carrier gas. This effect has been first observed by Campargue and co-workers in 2000, in the case of atomic oxygen seeded in argon. In the present paper, we develop a theoretical analysis of this effect, in the high dilution limit, and we compare our theoretical results to several experimental observations, including a set of measurements we have made on a beam of lithium seeded in argon. The agreement between theory and experiments is good.
超声速膨胀是产生具有明确速度的原子束的一种非常强大的工具，并且通过在这种膨胀过程中注入测试气体，测试气体的能量可以至少部分地转移到极低温的载气中。通常研究的情况是重气体注入轻载气的情况，在这种情况下，注入气体的平行温度总是高于载气的平行温度。在本文中，我们研究了较少受到关注的相反情况：当轻气体注入较重的载气中时，注入气体的平行温度可能会比载气的平行温度低得多。这种效应最早是由坎帕尔格及其同事在2000年观察到的，当时是原子氧注入氩气的情况。在本文中，我们在高稀释极限下对这种效应进行了理论分析，并将我们的理论结果与几个实验观测结果进行了比较，包括我们对注入氩气的锂束所做的一组测量。理论与实验之间的吻合度很好。
