Application of well-defined indium tin oxide nanorods as Raman active platforms

Abstract

We determine the surface enhanced Raman (SER) capability of indium tin oxide nanorods (ITO NRs) whose physical, chemical, and optical properties are precisely and uniformly controlled during synthesis. We demonstrate that the Raman intensities observed from varying concentrations of the pure and mixed molecules of rhodamine 6G and 4 0 ,6-diamidino-2-phenylindole are much larger on ITO NRs relative to those measured on commercially available ITO-coated glass or Si. Our efforts signify the first attempt to assess the SER capability of precisely controlled metal oxide NRs and will be highly beneficial to many basic and applied Raman applications requiring exceptional detection sensitivity. Surface enhanced Raman spectroscopy (SERS) is a powerful analytical tool which has proven its usefulness as a very selective and sensitive surface measurement technique. [1][2][3][4][5][6] In SERS, the majority of the substrates used for surface enhancement effects involve nanoparticles, thin films, islands, and three-dimensional constructs of coinage metals such as Cu, Au, and Ag. 2,7-9 Identifying potential SERS-active substrates and understanding enhancement mechanisms for such substrates are critical to the field and, therefore, still remain a key area of SERS study. Although not as extensively explored as the aforementioned metals, some research efforts are made to obtain SERS of transition metals such as Pt, Rh, Pd, Fe, Co, and Ni. 3,10-13 And more recently, other systems involving either a metal oxide thin film or a hybrid system of a metal nanoparticle/metal oxide thin film have been demonstrated as SERS-active materials. 7,14-19 Plasmonic characteristics similar to those observed from noble metals are found in some transparent conducting metal oxides such as indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide. 18,20 Despite many leading efforts on this aspect, only a small subset of research discusses Raman enhancement effects observed from nanomaterials that are precisely controlled for their physical, chemical, optical, or electrical properties during synthesis. Controlling the exact size and structure of the nanomaterials has not been the primary focus of many previous SERS studies, and many of the studies involve random surface roughening of Raman substrates for desired surface enhancement effect. Only more recently with the progress in nanoscience has it become an active subject matter of SERS investigation. 4,8,[21][22][23] When it comes to one-dimensional (1D) metal oxide nanomaterials which typically exhibit a higher aspect ratio than noble metal nanorods of a comparable diameter, concerted SERS measurements on controlled nanomaterial substrates are even scarcer. Yet, the anisotropy of 1D nanomaterials can provide a higher degree of enhancement in localized electromagnetic fields through symmetry breaking and can thus be extremely beneficial for SERS.In this letter, we report the SERS activity of wellcontrolled, anisotropic indium tin oxide nanorods (ITO NRs) by evaluating their role in Rama...

Indium Tin Oxide Nanowire Networks as Effective UV/Vis Photodetection Platforms

“…In this regard, we have previously demonstrated the different uses of indium tin oxide nanowire (ITO NW) network systems in biomolecular fluorescence and surface-enhanced Raman signal detection. 10 , 11 …”

Sputtered gold-coated ITO nanowires by alternating depositions from Indium and ITO targets for application in surface-enhanced Raman scattering

“…Zhao et al [39] synthesized ITO nanorods by thermal evaporation using gold as seed layer and tested these surfaces as SERS substrates. They obtained very good results and assigned them to the SERS effect from the ITO nanorods.…”

Preparation of Indium Tin Oxide Nanowires by Using physical-vapor-transport method

“…Recently, the research on ITO nanomaterials has attracted much attention due to the potential of developing applications in the miniaturization of sensors and high-performance optoelectronic devices [10,11] . According to earlier report, randomly arranged ITO nanorod arrays could be used as fluorescent labeling of biomolecules as well as surface-enhanced Raman signal detection [12][13][14][15] . Recently, we found that such ITO nanorod arrays can also be used as visible or UV detectors.…”