We have developed ultra fine probes with tungsten suboxide (WOx) nanorods for our multiple scanning probe microscopes since the fine probe is advantageous for reducing interprobe distance and reproducible small contacts to nanostructures. The WOx nanorods are epitaxially grown on tungsten probe apex. Since tungsten suboxide has high electrical conductivity, the ultra fine probe can be used as probes for STM and electrical measurements.
In addition, it is revealed that the WOx nanorod shows enhancement effect of Raman scattering. Small amount of molecules adsorbed on the nanorod are observable by Raman scattering spectroscopy. The WOx nanorods having width of 10 to 100 nm and length of 1 to 10 µm are transferred on Si substrate from tungsten probe. Rhodamine 6G (R6G) molecules are deposited on the surface by dropping 1nM R6G solution. Raman mapping were carried out by a Laser micro Raman spectrometer with a spot size of 1 µm. The results clearly showed Raman enhancement effect on the WOx nanorods. Mechanism of Raman enhancement will be discussed by considering the structure of the WOx nanorod. The WOx nanorod has planer defects of oxygen which are considered to form electrical conducting layers. That layered structure would play important role in enhancement effect of Raman scattering. The multifunctional ultra fine probe using the WOx nanorod will become useful in molecular electronics and nanobiotechnology since they can extract information about electrical properties and structure of molecules simultaneously with extremely high spatial resolution.
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