BIOLOGICAL APPLICATIONS OF A COMPUTER CONTROLLED ANALYTICAL ELECTRON MICROSCOPE

实验测量了相对 并行EELS和EDXS的灵敏度为一系列 生物微量分析中常见的元素。的 结果与理论推导的估计值进行了比较 基于散射截面和收集效率。 在Hitachi H700H上同时收集EELS和EDXS数据 分析电子显微镜能量损失谱收集在 第二差分模式，以消除通道到通道的增益变化。 使用参比光谱的多重最小二乘拟合定量 数据。结果表明，EELS不仅可以检测到轻元素 通过K壳层激发的高灵敏度，但也可以检测元素 例如钙、铁和磷。 EELS对钙的敏感性约为EELS的三倍 如果样品足够薄，则EDXS的结果会更好。的灵敏度 两种光谱中的铁含量大致相同。检出限 EELS的磷含量比EDXS低约六倍。

Experimental measurements have been made on the relative sensitivities of parallel EELS and EDXS for a series of elements commonly encountered in biological microanalysis. The results were compared with theoretically derived estimates based on scattering cross sections and collection efficiencies. The EELS and EDXS data were collected simultaneously on the Hitachi H700H analytical electron microscope. Energy loss spectra were collected in the second-difference mode to eliminate channel-to-channel gain variations. Multiple least squares fitting of reference spectra was used to quantitate the data. It was shown that EELS can detect not only the light elements with high sensitivity through the K-shell excitation but can also detect elements such as calcium, iron and phosphorus through the L-shell excitation. Sensitivity for calcium is shown to be about three times higher for EELS than for EDXS provided the sample is sufficiently thin. Sensitivities for iron are about the - same for the two spectroscopies. Detection limits for phosphorus are about six times lower for EELS than for EDXS.