Evanescent fields - direct measurement, modeling, and application

The evanescent field surrounding an exposed planar waveguide in silica is accurately measured using scanning near field optical microscopy (SNOM) and compared to models of the field distribution. Distortions in the field due to edge effects and the proximity of the mode to the surface are all detected. The characterized field is use to quantitatively explore the difference in collection efficiency between contact mode SNOM and intermittent contact mode SNOM. A strong correlation between tip oscillation amplitude and detection efficiency is determined.     

流动注射-阳离子交换预浓集ICP-AES法检测痕量元素铜、锌、铅、铬、镍

本文研究了阳离子交换树脂D401对待测元素Cu,Zn,Pb,Cd,Ni的预浓集及洗脱性能,并与改进的流动注射(FI)相接合,建立了一套新型、高效的FI-阳离子交换-ICP-AES分析体系。从而极大地提高了分析的速度和灵敏度,分析速度可达每小时20个样品。Cu、Zn、Pb、Cd、Ni各元素的检测限分别为0.25ng/ml、0.17ng/ml、0.94ng/ml、0.75ng/ml和0.60ng/ml。利用此体系做水样加标试验获得较好回收率(96％～107％),实际分析标准物大米粉(GBW08502)结果与标准值接近。