De Dea Silvia, Miller David R, Continetti Robert E
Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093-0001, USA.
J Phys Chem A. 2009 Jan 15;113(2):388-98. doi: 10.1021/jp805618z.
The free-jet expansions of high-pressure CO(2) supercritical solutions are probed by direct sampling mass spectrometry. Both cluster intensity measurements and velocity distribution measurements are reported for expansions which result in cluster formation by condensation and fragmentation of supersaturated vapors and superheated liquids. The resulting velocity distributions for these highly nonequilibrated expansions are characterized by up to three different peaks, depending on the source conditions: two primary peaks associated with very large clusters, the slower of which is associated with liquid fragmentation, and a smaller faster peak associated with monomers and small CO(2) clusters. We have associated the slow peak, observed only for fragmentation of superheated liquid expansions, with a liquid or condensed phase fragment by measuring the velocity distribution of low vapor pressure solutes in the expansion of supercritical CO(2) mixtures.
通过直接采样质谱法对高压二氧化碳超临界溶液的自由射流膨胀进行了探测。报告了通过过饱和蒸汽和过热液体的冷凝和破碎形成团簇的膨胀过程中的团簇强度测量和速度分布测量结果。这些高度非平衡膨胀产生的速度分布的特征是，根据源条件，有多达三个不同的峰值：两个主要峰值与非常大的团簇相关，其中较慢的一个与液体破碎相关，还有一个较小的较快峰值与单体和小二氧化碳团簇相关。通过测量超临界二氧化碳混合物膨胀中低蒸气压溶质的速度分布，我们将仅在过热液体膨胀破碎时观察到的慢峰与液相或凝聚相碎片联系起来。
