| 摘要 |
Apparatus and method for examining the identity of chemical groups in a sample are disclosed. The apparatus has a substrate having a plasmon resonant surface on which the sample is supported, a source of a beam of light, and a lens assembly having a tip region and a nanolens composed of one or more plasmon resonance particles (PRPs) on the tip region. The PRPs are arranged to produce near-field electromagnetic gap modes in a space between the nanolens and a confronting detection region on the substrate surface when the gap between the nanolens and substrate is 30 nm or less. A focusing mechanism in the apparatus operates to move the lens assembly toward and away from the substrate surface, with a gap of less than 30 nm, to produce electromagnetic gap modes that enhance the Raman spectroscopy signals produced by the sample in the detection region. The apparatus and method are useful, for example, in identifying successive bases in a single DNA strand, for direct DNA sequencing. |
