Satoru Suzuki

Abstract We would like to improve detection sensitivity by making photoelectron transmission window (SiNx membrane) of liquid cell ultra-thin for liquid measurement using XPS or X-ray PEEM at UHV. In this study, thinning of the membrane using gas cluster ion beams (GCIB) was demonstrated and the burst pressure was compared with those thinned with atomic 400 eV Ar+ ions. It was shown that SiNx membranes thinned by GCIB was 2.5 times higher burst pressure than the Ar+ ions. In addition, improvement of sensitivity of characteristic X-ray from liquid-water induced by low-energy electrons was investigated. By using 4.5 nm thick SiNx membrane etched by GCIB, the X-ray intensity became 1.6 times higher than those from 11 nm thick pristine membrane at electron beam energy of 1.5 keV. This result showed good agreement with Monte Carlo simulation results of the electron-beam-induced X-ray emission from liquid-water beneath SiNx membrane.

We investigated the chemical composition of polytetrafluoroethylene (PTFE) under bending stress using hard X-ray photoelectron spectroscopy and soft X-ray absorption spectroscopy. Our measurements revealed the breaking of C–F bonds in the side chains and conspicuous observation of C–C bonds in the main chain only on the surface under bending stress (carbon-rich). Moreover, we found that the breaking of C–F bonds was dependent on the tensile strain caused by bending. Investigating the effects of tensile and compressive stresses induced by bending, the tensile stress was found to significantly contribute to the breaking of C–F bonds. However, the C–F bonds were hardly broken under uniaxial tensile stress. These findings suggest that tensile stress due to bending, rather than uniaxial tensile stress, causes significant C–F bond scission in the PTFE. This result is attributed to the force acting toward the center of curvature owing to bending, which does not occur under uniaxial tensile stress. Our results provide a better understanding of microscopic PTFE surfaces subjected to flexural tensile stress for nanofluidics and medical engineering applications. Additionally, our findings suggest that carbon-rich structures can be easily fabricated, which may lead to the development of processes for fabrication of two-dimensional materials.