The possibility of utilizing the Si and Ge nanostructures to promote surface-enhanced Raman scattering (SERS) is discussed. The vibronic coupling of the conduction band and valence band states of Si or Ge with the excited and ground states of the target molecule during the charge transfer (CT) process could enhance the molecular polarizability tensor. Using H-terminated silicon nanowire (H-SiNW) and germanium nanotube (H-GeNT) arrays as substrates, significant Raman enhancement of the standard probes, Rodamine 6G (R6G), dye (Bu(4)N)(2)[Ru(dcbpyH)(2)-(NCS)(2)] (N719), and 4-aminothiophenol (PATP), are demonstrated. The abundant hydrogen atoms terminated on the surface of SiNW and GeNT arrays play a critical role in promoting efficient CT and enable the SERS effect.

Surface-Enhanced Raman Scattering (SERS) spectroscopy has experienced a rapid growth over the past 30 years, and has become a valuable tool in various research areas. In conjunction with recent explosive development of nanoscience and nanotechnology, the SERS-active substrates have also expanded from traditional Group 11 metals (Au, Ag, Cu) to non-Group 11 nanostructures. This paper gives an overview of historical advances in the use of non-Group 11 nanostructures as substrates for SERS. Several possible mechanisms and important factors for SERS from non-Group 11 nanostructures are discussed in detail. The SERS from non-Group 11 nanostructures provides many significant applications in surface, interface analysis and biochemical detection. It is reasonable to believe that the advancement in the non-Group 11 nanostructures-based SERS-active substrates will lead to a more promising future for the SERS technology in surface science, spectroscopy and biomedicine.

Si nanowires (SiNWs) were covalently modified by fluorescence ligand, N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QlOEt) and finally formed an optical sensor to realize a highly sensitive and selective detection for Cu(II). The QlOEt-modified SiNWs sensor has sensitivity for Cu(II) down to 10(-8) M, which is more sensitive than QlOEt alone. Metal ions interferences have no observable effect on the sensitivity and selectivity of QlOEt-modified SiNWs sensor. The SiNWs-based fluorescence sensor is reversible by addition of acid to replace Cu(II). The sensing mechanisms of QlOEt-modified SiNWs to Cu(II) and the rationale for the increase in sensitivity and selectivity of QlOEt-modified SiNWs over QlOEt on Cu(II) are discussed. The current sensor structure may be extendable to other chemo- and biosensors, and even to nanosensors for direct detection of specific materials in intracellular environment.