Development of single molecule absorption spectroscopy

吸收光谱法在分子鉴定中是有用的，但其灵敏度受光源强度波动和探测器噪声的限制。为了提高灵敏度，由于吸光度与照明面积成反比，因此将照明面积缩小到纳米尺度是有希望的。在本研究中，为了减少照明面积，利用了孔径近场探头的局部照明。制作了近场光纤探头，研究了提高灵敏度的工作原理。该技术提高了纳米材料的吸收灵敏度，可以获得具有广泛光谱范围的有价值的光谱信息。单分子灵敏度还没有达到，但是，通过改进近场探测器的制造，它将在不久的将来实现。

Absorption spectroscopy is useful for molecular identifications, while its sensitivity is limited by intensity fluctuation of light source and noises of a detector. In order to improve the sensitivity, miniaturization of the illumination area down to nanometer scale is promising since the absorbance is inversely proportional to the illumination area. In this study, to reduce the illumination area, local illumination of the apertured near-field probe was utilized. The near-field fiber probe was fabricated, and the operation principle for enhancing the sensitivity was examined. Absorption sensitivity was enhanced with this technique, and the improvement enables to obtain valuable spectroscopic information on nanomaterials with wide spectral range. . A single molecular sensitivity has not yet been achieved, however, by improving the fabrication of the near-field probe it will be realized in near future.