To evaluate sample degradation during XPS measurement, a round-robin test involving five laboratories was carried out with four kinds of samples such as cellulose nitrate (NC), polyvinyl chloride (PVC), silicon wafer modified with chloropropyltriethoxysilane (CPTES-Si) and gold substrate modified with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT-Au) as model samples. In each sample, the degradation behavior followed first-order kinetics with respect to the relative dose provided by the peak intensity of either Ag 3d5/2 or Au 4f derived from Ag or Au substrates, respectively, as an index of X-ray dose. The result shows that the rank order of the damaging factors of samples was almost the same in each apparatus, but the obtained values were different among the apparatuses. On the other hand, from comparison of Au and Ag substrates for calculating relative X-ray dose, it can be seen that the damaging factors using those two metal substrates are almost equivalent. Considering the convenience in handling and the sputtering process, we concluded that Au substrate is more suitable for an index material to estimate relative X-ray dose. Furthermore, the relative damaging factor RDF, i.e. the damaging factor of each material divided by that of PFDT-Au as a reference material, did not depend on the difference of the apparatuses, and indicated close value for each sample, suggesting that the RDF should have universality and provide an useful information for evaluating sample degradation. Thus, the construction of that database would allow the prediction of the sample degradation by measuring degradation behavior of PFDT-Au as a reference material.

　X線光電子分光法は固体材料の表面分析に広く利用されている．ここでは，ラングミュア－ブロジェット膜や自己組織化膜といった有機薄膜の，著者らによる測定結果とそのスペクトルの解析技術について紹介する．

　本連載の最終章として，電子光学系における結像と電子分光に関するテーマをいくつか述べます．まず，従来の結像光学系とエネルギーアナライザを組み合せた電子分光結像系を説明します．この系においては，通常の分光系や電子顕微鏡とは違った特別な光学条件が要求されます．次に，電子光学系による結像の方式としてのTEM，SEM，STEMの等価性を相反定理を用いて示します．最後に，電子光学系の設計のために用いられる数値計算の技法をいくつか紹介します．

　光電子分光（PES: photoemission electron spectroscopy）の全体的な歴史について，Einsteinの光電効果の発見から最近の研究まで概説する．また，PESの基礎原理と中心的な概念について，実験及び理論の両面から概説する．さらに，近年の物質科学において重要な役割を担っているPESを基にした様々な実験についても紹介する．