Structured environment controls dynamics of light-matter interaction processes via modified local density of electromagnetic states. In typical scenarios, where nanosecond-scale fluorescent processes are involved, mechanical conformational changes of the environment during the interaction processes can be safely neglected. However, slow decaying phosphorescent complexes (e.g., lanthanides) can efficiently probe micro- and millisecond scale motion via near-field interactions with nearby structures. As the result, lifetime statistics can inherit information about nanoscale mechanical motion. Here we study light-matter interaction dynamics of phosphorescent dyes, diffusing in a proximity of a plasmonic nanoantenna. The interplay between time-varying Purcell enhancement and stochastic motion of molecules is considered via a modified diffusion equation, and collective decay phenomena is analysed. Fluid properties, such as local temperature and diffusivity, are mapped on phosphorescent lifetime distribution and then extracted with the help of inverse Laplace transformation. The presented photonic platform enables performing contactless all-optical thermometry and diffusion measurements, paving a way for a range of possible applications. In particular, detailed studies of nanofluidic processes in lab-on-a-chip devices, challenging for analysis with other optical methods, can be performed with time-dependent phosphorescence.

中文翻译：

---

纳米结构环境中受扩散启发的时变磷光衰减

结构化环境通过修改的电磁状态局部密度来控制光物质相互作用过程的动力学。在涉及纳秒级荧光过程的典型场景中，可以安全地忽略相互作用过程中环境的机械构象变化。但是，缓慢衰减的磷光络合物（例如镧系元素）可以通过与附近结构的近场相互作用有效地探测微秒级和毫秒级的运动。结果，寿命统计可以继承有关纳米级机械运动的信息。在这里，我们研究了在等离激元纳米天线附近扩散的磷光染料的光-质相互作用动力学。通过修正的扩散方程考虑了随时间变化的赛尔增强与分子随机运动之间的相互作用，分析了集体衰变现象。将流体特性（例如局部温度和扩散率）映射到磷光寿命分布上，然后借助拉普拉斯逆变换进行提取。提出的光子平台能够执行非接触式全光学测温和扩散测量，为一系列可能的应用铺平了道路。尤其是，可以通过与时间有关的磷光来进行芯片实验室设备中的纳米流体过程的详细研究，这些挑战对其他光学方法的分析提出了挑战。提出的光子平台能够执行非接触式全光学测温和扩散测量，为一系列可能的应用铺平了道路。尤其是，可以通过与时间有关的磷光来进行芯片实验室设备中的纳米流体过程的详细研究，这些挑战对其他光学方法的分析提出了挑战。提出的光子平台能够执行非接触式全光学测温和扩散测量，为一系列可能的应用铺平了道路。尤其是，可以通过与时间有关的磷光来进行芯片实验室设备中的纳米流体过程的详细研究，这些挑战对其他光学方法的分析提出了挑战。