Fluorescence from airborne microparticles: dependence on size, concentration of fluorophores, and illumination intensity
Fluorescence from airborne microparticles: dependence on size, concentration of fluorophores, and illumination intensity
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DOI：
10.1364/ao.40.003005
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发表时间：
2001-06-20
期刊：
影响因子：
1.9
通讯作者：
Chang, RK
中科院分区：
文献类型：
--
作者：
Hill, SC;Pinnick, RG;Chang, RK
我们测量了含有色氨酸的球形水滴和细菌细胞聚集体的荧光，并将这些测量结果与电介质球的荧光计算进行了比较。从液滴和细菌的干颗粒聚集体测量的荧光对大小的依赖性与包含适当百分比的色氨酸的均匀球体计算的吸收截面成比例。然而，随着水滴中色氨酸浓度的增加，测得的液滴荧光增加小于预测，可能是因为浓度猝灭。我们通过假设荧光发射事件之间的平均时间是荧光寿命和激发寿命（被照射分子被激发所需的平均时间）的总和来模拟荧光对输入强度的依赖性，我们假设粒子内部的强度是均匀的。即使粒子内部的强度在空间上变化，这种均匀强度的假设仍然导致与测量的强度依赖性一致的结果。(C)2001年美国光学学会。
We measured fluorescence from spherical water droplets containing tryptophan and from aggregates of bacterial cells and compared these measurements with calculations of fluorescence of dielectric spheres. The measured dependence of fluorescence on size, from both droplets and dry-particle aggregates of bacteria, is proportional to the absorption cross section calculated for homogeneous spheres containing the appropriate percentage of tryptophan. However, as the tryptophan concentration of the water droplets is increased, the measured fluorescence from droplets increases less than predicted, probably because of concentration quenching. We model the dependence of the fluorescence on input intensity by assuming that the average time between fluorescence emission events is the sum of the fluorescence lifetime and the excitation lifetime (the average time it takes for an illuminated molecule to be excited), which we calculated assuming that the intensity inside the particle is uniform. Even though the intensity inside the particles spatially varies, this assumption of uniform intensity still leads to results consistent with the measured intensity dependence. (C) 2001 Optical Society of America.