Precision control of vaporization, both in space and time, is critical for numerous applications, including medical imaging and therapy, catalysis and energy conversion, and it can be greatly improved through the use of micro- or nano-sized light absorbers. Ultimately, optimization of these applications also requires a fundamental understanding of the vaporization process. Upon laser irradiation, polymeric microcapsules containing a dye can vaporize, leading to the growth of a vapor bubble that emits a strong acoustic signature. Here, we compare laser-activated capsules containing either a volatile or a non-volatile oil core. We theoretically explore the vaporization of the capsules based on a three-phase thermodynamics model, that accounts for the partial vaporization of both the surrounding fluid and the oil core as well as for the interaction between heat transfer and microbubble growth. The model is compared to ultra-high-speed imaging experiments, where we record the cavitation events. Theory and experiments are in convincing agreement.

时空上的精确汽化控制对于包括医学成像和治疗，催化和能量转换在内的许多应用而言至关重要，并且可以通过使用微米或纳米级的光吸收剂来大大改善。最终，优化这些应用还需要对蒸发过程有基本的了解。在激光辐照下，含有染料的聚合物微囊会蒸发，从而导致蒸气泡的生长，并发出强烈的声学信号。在这里，我们比较了包含挥发性或非挥发性油核的激光激活胶囊。我们从理论上探讨了基于三相热力学模型的胶囊的汽化，这说明了周围流体和油芯的部分汽化，以及热传递和微泡生长之间的相互作用。该模型与超高速成像实验进行了比较，在超高速成像实验中我们记录了空化事件。理论和实验令人信服。