Randomly rotating particles that have been isotropically labeled with rigidly linked fluorophores will undergo non-isotropic (patchy) photobleaching under illumination due to the dipole coupling of fluorophores with light. For a rotational diffusion rate D of the particle and a photobleaching time scale $\tau$ of the fluorophores, the dynamics of this process are characterized by the dimensionless combination $D\tau$. We find significant interparticle fluctuations at intermediate $D\tau$. These fluctuations vanish at both large and small $D\tau$ or at small or large elapsed times t. Associated with these fluctuations between particles, we also observe transient non-monotonicities of the brightness of individual particles. These non-monotonicities can be as much as 20% of the original brightness. We show that these novel photobleach-fluctuations dominate over variability of single-fluorophore orientation when there are at least 10³ fluorophores on individual particles.

中文翻译：

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随机旋转的荧光装饰颗粒的光漂白

各向同性标记有刚性连接的荧光团的随机旋转粒子，由于荧光团与光的偶极耦合，在光照下将发生非各向同性（斑片）光致漂白。对于粒子的旋转扩散速率D和光漂白时间标度$\tau$ 的荧光团，此过程的动力学特征在于无量纲的组合 $d\tau$。我们发现在中间存在明显的粒子间波动$d\tau$。这些波动无论大小都会消失$d\tau$或在较小或较大的经过时间t。与粒子之间的这些波动相关联，我们还观察到了单个粒子亮度的瞬时非单调性。这些非单调性可能高达原始亮度的20％。我们表明，当在单个颗粒上至少存在10 ^3个荧光团时，这些新颖的光漂白涨落在单个荧光团取向的变异性上占主导地位。