Extinction Cross Section Measurements for Single Aerosol Particles Confined to a Linear Electrodynamic Quadrupole Trap

翻译后摘要：气溶胶粒子可以散射和吸收太阳和地面辐射，与散射具有冷却效果的大气和吸收变暖的效果。辐射与吸收气溶胶粒子的相互作用是目前全球气候模式中最大的不确定性之一[1]。因此，将开发一种新的技术，可以精确地确定弱吸收和强吸收气溶胶粒子的辐射对全球气候的影响。对于0.5-1 Tm尺寸范围内的颗粒，非吸收性气溶胶颗粒的测定折射率（RI）值的准确度为0.1%[2]。然而，由于贝塞尔光束（BB）光阱产生的粒子上的电泳力，限制吸收气溶胶粒子被证明是困难的。在该项目中，将开发一种利用线性电动四极（LEQ）阱的CRDS装置，以精确捕获吸收粒子。新技术的准确性将通过与已建立的蒸发有机物和吸湿无机物的测量结果进行比较来验证。然后，工作将开始，以确定散射和吸收的吸收气溶胶颗粒，即棕色碳（BrC）物种的RI的组件。该项目的后期阶段可能允许探索气溶胶颗粒消光的混合状态、形态和加工（例如氧化老化）依赖性。

Abstract:Aerosol particles can both scatter and absorb solar and terrestrial radiation, with scattering having a cooling effect on the atmosphere and absorption a warming effect. The interaction of radiation with absorbing aerosol particles is currently oneof the largest uncertainties in global climate models [1]. Therefore, a new technique will be developed allowing accurate determination of the effect of irradiation of both weakly and strongly absorbing aerosol particles on global climate.Cavity ring-down spectroscopy (CRDS) measurements reported by Cotterell et al., determined refractive index (RI) values for non-absorbing aerosol particles to an accuracy of 0.1% for particles in the 0.5-1 Tm size range [2]. However, confinementof absorbing aerosol particles proved difficult, owing to photophoretic forces acting on the particles created by the Bessel beam (BB) optical trap employed. During this project, a CRDS set-up utilising an linear electrodynamic quadrupole (LEQ) trap will be developed allowing precise trapping of absorbing particles. The accuracy of the new technique will be validated by comparison with well established measurements of evaporating organic and hygroscopic inorganic species. Work will then begin to determine both the scattering and absorption components of the RI of absorbing aerosol particles, namely brown carbon (BrC) species. Later stages of the project may allow exploration of the mixing state, morphology and processing (e.g. oxidative ageing) dependency of aerosol particle light extinction.