We present the enhancement of the hot-electron emissions by the enhanced electric field with deep UV surface plasmon resonance (DUV-SPR). An aluminum disk–hole array was designed using the finite-difference time-domain (FDTD) method for enhancing the electric field by the disk–hole cavity coupling. We found that the photoelectron emission efficiencies were experimentally improved by four times and that the disk–hole distance was a key factor to induce the strong disk–hole coupling. The aluminum disk–hole array with DUV-SPR would be expected for many applications, such as the highly sensitive photodetectors, the photoelectron guns, and the efficient photocatalysts.
Autofluorescence in living cells on aluminum thin film was excited with deep-ultraviolet surface plasmon resonance (deep-UV SPR). Deep-UV SPR under aqueous medium was excited with Kretschmann configuration by using a sapphire prism. Deep-UV SPR is one of the promising techniques for high-sensitive autofluorescence imaging of living cells without staining. Label-free observation is significant for the structural analysis of living cells. We demonstrated the high-sensitive autofluorescence imaging of living yeast cells with deep-UV SPR. We applied a high refractive index prism, such as sapphire, which is suitable for the observation of specimens in aqueous medium, to excite deep-UV SPR. Although typical autofluorescence from living cells is buried in background noise, deep-UV SPR enhances the autofluorescence signal. The deep-UV SPR excitation of an aluminum thin film through a sapphire prism was investigated theoretically and experimentally. It showed that the fluorescence intensities are increased 2.8-fold. Deep-UV SPR enhanced the autofluorescence of cell structures, and yeast cells were found to be very sensitive. As a result, for water-immersed specimens, the sapphire-prism-based Kretschmann configuration excited SPR in deep-UV. Findings from this study suggest that deep-UV SPR can be considered an effective technique for attaining high-sensitivity observation of biological samples.
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