We measured the nucleation rates of n-pentane through n-heptane in a supersonic nozzle at temperatures ranging from ca. 109 K to 168 K. For n-pentane and n-hexane, these are the first nucleation rate measurements that have been made, and the trends in the current data agree well with those in the earlier work of Ghosh et al. [J. Chem. Phys. 132, 024307 (2010)] for longer chain alkanes. Complementary Monte Carlo simulations, using the transferable potentials for phase equilibria-united atom potentials, suggest that despite the high degree of supercooling, the critical clusters remain liquid like under experimental conditions for n-pentane through n-heptane, but adopt more ordered structures for n-octane and n-nonane. For all three alkanes, the experimental and simulated nucleation rates are offset by ∼3 orders of magnitude when plotted as a function of ln S/(T_c/T − 1)^1.5. Explicitly accounting for the surface tension difference between the real and model substances, or alternatively using the Hale [Phys. Rev. A 33, 4156 (1986); Metall. Mater. Trans. A 23, 1863 (1992)] scaling parameter, Ω, consistent with the model potential, increases the offset to ∼6 orders of magnitude.

中文翻译：

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短链正构烷烃（正戊烷，正己烷和正庚烷）的气相成核：实验和蒙特卡洛模拟

我们测量的成核速率Ñ戊烷通过Ñ庚烷在超音速喷嘴在温度范围约 109 K至168 K.对于ñ戊烷和ñ正己烷，这是第一次核率的测量已取得的，而在当前的数据趋势与那些在早期戈什的工作吻合等。[J. 化学 物理 132，024307（2010）]为较长链烷烃。互补的蒙特卡洛模拟，使用相平衡单元原子势的可转移势，表明尽管过冷程度很高，但像在正戊烷到氢的实验条件下一样，临界团簇仍保持液态正庚烷，但对正辛烷和正壬烷采用更有序的结构。对于所有三种烷烃，当绘制成ln S /（T _c / T − 1）^1.5的函数时，实验和模拟的成核速率都可偏移约3个数量级。明确考虑真实物质与模型物质之间的表面张力差异，或者使用Hale [Phys。修订版A 33，4156（1986）; Metall。母校 反式 一个23，1863年（1992年）]缩放参数，Ω，与模型潜力一致，增加了偏移幅度〜6台的订单。