Using X-ray absorption spectroscopy (XAS) with linearly polarized soft X-rays, we investigated the local conformation of poly(methyl methacrylate) (PMMA) adsorbed to a SiO_x/Si(111) surface. The preedge intensity of the O K-edge XAS for PMMA, originating from the O 1s → π^* transition at a C=O group in the side chain, was stronger for vertically polarized incident X-rays than for horizontally polarized ones. Conversely, the XAS intensity originating from the O 1s → σ^* transition showed the opposite trend. These findings suggest that the C=O group in the side chain of PMMA exhibited preferential orientation rather than an amorphous arrangement. To gain further insights, we conducted a depth profile analysis of the local conformation of PMMA using XAS combined with an argon gas cluster ion beam (GCIB). GCIB-XAS analysis revealed that the orientation of the C=O group in the side chain of PMMA differs between the region from the SiO_x interface to a distance on the order of 1 nanometer and the bulk PMMA region.

_{使用线性偏振软 X 射线的 X 射线吸收光谱 (XAS)，我们研究了吸附在 SiO x} /Si(111)表面上的聚甲基丙烯酸甲酯 (PMMA) 的局部构象。PMMA 的 O K 边缘 XAS 的预边缘强度源自侧链 C=O 基团处的 O 1s → π ^*跃迁，垂直偏振入射 X 射线的预边缘强度比水平偏振入射 X 射线更强。相反，源自O 1s → σ ^*跃迁的XAS强度显示出相反的趋势。这些发现表明PMMA侧链中的C=O基团表现出择优取向而不是无定形排列。为了获得进一步的见解，我们使用 XAS 结合氩气团簇离子束 (GCIB) 对 PMMA 的局部构象进行了深度剖面分析。GCIB-XAS分析表明，PMMA侧链中C=O基团的取向在距SiO _x界面至1纳米数量级的区域和本体PMMA区域之间有所不同。