瑞利散射法诊断大尺寸团簇

Diagnoses of Large Clusters by Rayleigh Scattering

瑞利散射法的优点是实验易行，对于团簇是非破坏性的。利用这种方法，Ａ．Ｊ．Ｂｅｌｌ等人测出了尺寸在１５０～４０００的氩团簇。Ｒ．Ｋｌｉｎｇｅｌｈ氹ｆｅｒ测量了瑞利散射信号强度同散射角的依赖关系，推断出氢团簇尺寸分布。Ｔ．Ｄｉｔｍ ｉｒｅ等在散射角固定不变（θ＝ ９０）的情况下，测量散射信号同气体滞止压强Ｐ０ 或温度Ｔ０ 的关系，从而推断团簇的尺寸。Ｈ２在７９ Ｋ及Ａｒ在２９３Ｋ，瑞利散射信号同压强的标定关系为≈Ｐ３．８０ 和Ｐ３．６０ ，分别测得最大团簇尺寸Ｎｃ ≈６９０（Ｈ２）和１１６０（Ａｒ）。对于Ａｒ在１４７ Ｋ，背景压强低于３５ ｋＴｏｒｒ时， ＳＲＳ∝Ｐ３．８０ ，而在更高的压强下，ＳＲＳ ∝Ｐ４．３０ ， 所产生团簇最大尺寸约为３．５×１０４。

Rayleigh scattering method is a light scattering method ,the advantage of which is its easiness to perform and non disruptive. With this method ,Ar clusters in the range of 150 to 4000 were detected by A.J.Bell et al.,R.Klingelhofer et al. also detected the angular dependence of scattering intensity and the resulted cluster size distribution. The stagnation pressure P 0 and temperature T 0 dependence of scattering signals is studied by T.Ditmire et al.. The size of clusters produced under different conditions was diagnosed. For H 2 at 79 K and Ar at 293 K,Rayleigh scattering signals scale as ≈P 3.8 0 and P 3.6 0,respectively gave the peak cluster size N c of ≈690 and 1160. For cooled Ar at 147 K,it was found an initial pressure scaling ≈P 3.8 0 below 35 kTorr and a more rapid scaling of ≈P 4.3 0,whose peak implies a cluster size of ≈3.5×10 4.