标题： 使用通用四臂拉盖尔-高斯模式光阱捕获吸收性和非吸收性水粒子 显示英文标题

标题： Trapping absorbing and non-absorbing aqueous particle using a universal 4-arm Laguerre-Gaussian mode light trap

摘要： 吸收性气溶胶，如棕碳（BrC）和吸收性二次有机气溶醇（SOA），由于其在气候和人类健康方面的重要性而引起了广泛关注。 在老化过程中光吸收的显著时间依赖性使得精确估计其对全球变暖的影响变得困难。 对这类气溶胶的单颗粒研究将非常有用，可以通过光化学等过程更好地理解它们在大气中的老化。 然而，以前提出的光学陷阱无法连续捕获吸收状态从强吸收变为非吸收或反之的颗粒。 一些展示的陷阱可以分离吸收性和非吸收性颗粒，但需要根据颗粒吸收强度进行机械对准。 然而，机械重新对准与连续捕获和观察不兼容。 在这里，我们介绍了一种灵活的光学通用陷阱，不需要机械重新对准。 该陷阱的多功能性依赖于四个捕获光束——要么是涡旋拉盖尔-高斯（LG）光束，要么是基模高斯光束——这些光束通过空间光调制器（SLM）进行调制。 通过捕获不同类型的吸收性和非吸收性颗粒来演示该陷阱的性能。 我们还表明，该陷阱可用于观察含有富里酸的水滴的光化学反应，富里酸是BrC的常见成分。 数字全息测量表明，通过改变LG光束的轨道角动量（OAM）可以控制颗粒在陷阱中的约束。 该研究还表明，在所提出的陷阱的所有配置中，光谱测量，如荧光和拉曼散射，都是可行的。 显示英文摘要

摘要： Absorbing aerosols, such as brown carbon (BrC) and absorbing secondary organic aerosols (SOA), has attracted broad interest due to their importance for climate and human health. The pronounced time-dependence of light absorption during aging renders the precise estimation of their impact on global warming difficult. Single particle studies of such aerosols would be very useful to better understand their aging in the atmosphere through processes such as photochemistry. However previously proposed optical traps cannot continuously trap particles whose absorption state changes from strongly absorbing to non-absorbing or vice versa. Some of the traps presented can isolate absorbing and non-absorbing particles, but require mechanical alignment of the trap depending on the strength of particle absorption. However, mechanical realignment is not compatible with continuous trapping and observation. Here, we introduce a flexible optical universal trap which does not require mechanical realignment. The versatility of the trap relies on four trapping beams - either vortex Laguerre- Gaussian (LG) or fundamental Gaussian beams - which are modulated with a spatial light modulator (SLM), The performance of the trap is demonstrated by trapping different types of absorbing and non-absorbing particles. We also show that the trap can be used to observe the photochemical reaction of aqueous droplets containing fulvic acid, a common component of BrC. Digital holography measurements demonstrate that the confinement of the particles in the trap can be controlled by changing the orbital angular momentum (OAM) of the LG beams. The study also shows that spectroscopy measurements, such as fluorescence and Raman scattering, are possible in all configurations of the proposed trap.