Under nonequilibrium conditions, inorganic systems can produce a wealth of life-like shapes and patterns which, compared to well-formed crystalline materials, remain widely unexplored. A seemingly simple example is the formation of salt deposits during the evaporation of sessile droplets. These evaporites show great variations in their specific patterns including single rings, creep, small crystals, fractals, and featureless disks. We have explored the patterns of 42 different salts at otherwise constant conditions. Based on 7,500 images, we show that distinct pattern families can be identified and that some salts (e.g., Na 2 SO 4 and NH 4 NO 3 ) are bifurcated creating two distinct motifs. Family affiliations cannot be predicted a priori from composition alone but rather emerge from the complex interplay of evaporation, crystallization, thermodynamics, capillarity, and fluid flow. Nonetheless, chemical composition can be predicted from the deposit pattern with surprisingly high accuracy even if the set of reference images is small. These findings suggest possible applications including smartphone-based analyses and lightweight tools for space missions.

中文翻译：

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照片中的化学成分：干燥的溶液滴揭示了形态发生树


在非平衡条件下，无机系统可以产生丰富的逼真形状和图案，与结构良好的晶体材料相比，这些形状和图案尚未得到广泛探索。一个看似简单的例子是固着液滴蒸发过程中盐沉积的形成。这些蒸发岩的具体图案表现出巨大的变化，包括单环、蠕变、小晶体、分形和无特征的圆盘。我们探索了 42 种不同盐在其他恒定条件下的模式。基于 7,500 张图像，我们表明可以识别不同的图案家族，并且一些盐（例如 Na 2 SO 4 和 NH 4 NO 3 ）被分成两部分，形成两个不同的图案。家族隶属关系不能仅从成分中先验地预测，而是从蒸发、结晶、热力学、毛细管作用和流体流动的复杂相互作用中产生。尽管如此，即使参考图像集很小，也可以从沉积图案中以惊人的高精度预测化学成分。这些发现表明了可能的应用，包括基于智能手机的分析和用于太空任务的轻型工具。