Nanoscopy

Tip-enhanced Raman scattering (TERS) experiments of histidine immobilized on an atomically flat silver surface are presented. The substrate consists of silver nanoplates with a diameter of a few micrometers and a height about 20 nm. At such heights, the plates are still transparent to visible wavelengths, which is important for optimal illumination and detection. The Raman spectroscopic results strongly support a homogeneous adsorption of chemically different states of histidine on the silver surface. In addition, the influence of the silver surface and the TERS tip on the spectra of histidine is discussed with respect to the multiple coordination centers in the molecule.