原文由 tututututu 发表:
原文由 tututututu 发表:
我来问一个问题。
XRF 作为检测仪器,它的X-RAY对不同样品的品均穿透深度是多少?比如说塑料,金属,陶瓷,玻璃?穿透深度是由什么决定的?那么有些仪器的准直器的光斑是可以改变的,这主要的目的是什么?与穿透深度由关系吗?
这个问题请参考本版有关XRF的培训资料以及本论坛内有关XRF设备的论述。
大虾还是详细叙述一下吧,我觉得这非常之关键!
请参考IEC62321原文资料:Specimens that are too small or very thin may easily violate the condition of minimum sample thickness or mass that shall be present in order for the results to be valid. In such instances a number of small objects of the same kind (for example small screws) should be placed in a sample cup and then only analyzed. Similarly, thin samples of the same kind should be stacked in the pile thick enough to fulfill the minimum sample thickness criterion and analyzed accordingly. As a general rule, all samples shall completely cover the measuring window/area of the spectrometer. The sample should
be at least 5 mm thick in case of polymers and light alloys such as Al, Mg or Ti, minimum of 15 mm thick in case of liquids and about 1 mm thick for all other alloys. The insulation on thin wires and ribbon cables may not be treated as uniform and should be measured by extracting the metal conductor first. On the other hand, almost
all power cords of diameter larger than 5 mm with copper wiring inside, may be treated as uniform for the purpose of insulation analysis. The metal may also be analyzed, after separation. Some metal coatings may be analyzed, if the user knows the construction of the material, and the spectrometer is calibrated to analyze such a
complex layer system. For example, the coatings is known to be SnAgCu (plated over) Copper (plated over) epoxy. The tin alloy may be analyzed, provided the instrument is calibrated for this specific sample type. It is commonly accepted that most XRF instruments will not detect, with sufficient sensitivity, Cr in conversion coatings unless they are at least a few hundred nm in thickness. Due to variations from instrument to instrument of the required sample size, the operator of the spectrometer is advised to always consult the instrument manual or manufacturer for requirements on minimum
size/mass/thickness conditions of the sample.