No stopping 1D crystals Crystal nuclei—the minute collections of molecules needed to spark crystal growth—are small, short-lived, and generally unobserved. Classical nucleation theory, a model for the earliest stages of crystallization, is an accounting of the free-energy debits for creating an interface between crystals and the medium from which they grow, and the free energy credits for enlarging the interior of the crystal (1, 2). On page 1135 of this issue, Chen et al. (3) report the growth of one-dimensional (1D) peptide crystals in rows on crystalline substrates, which subsequently assemble laterally row by row into films (and ultimately 2D arrays) (see the figure). Growth rates along and perpendicular to the rows, measured by scanning probe microscopy, support the absence of an activation barrier that typically must be surmounted to overcome the surface energy. This unexpected challenge to the classical nucleation theory arises from high-resolution imaging that captures kinetic measurements for very small molecular aggregates (4). No matter the sophistication of our models, looking ever more closely at growing crystals often reveals unanticipated mechanisms (5).

中文翻译：

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屏障（少）岛屿

永不停歇的一维晶体 晶核——激发晶体生长所需的微小分子集合——很小、寿命很短，而且通常无法观察到。经典成核理论是最早结晶阶段的模型，它计算了在晶体与其生长介质之间产生界面的自由能借项，以及扩大晶体内部的自由能学分 (1 , 2). 在本期第 1135 页，Chen 等人。(3) 报告了一维 (1D) 肽晶体在晶体基板上成行生长，随后逐行横向组装成薄膜（并最终形成二维阵列）（见图）。沿着和垂直于行的生长率，通过扫描探针显微镜测量，支持不存在通常必须克服以克服表面能的激活障碍。对经典成核理论的这一意想不到的挑战源于高分辨率成像，该成像捕获了非常小的分子聚集体的动力学测量值 (4)。无论我们的模型多么复杂，更仔细地观察生长的晶体往往会发现意想不到的机制 (5)。