Tip‐Enhanced Near‐Field Optical Microscopy

Abstract

Tip-enhanced near-field optical microscopy (TENOM) is a scanning probe technique capable of providing a broad range of spectroscopic information on single objects and structured surfaces at nanometer spatial resolution and with highest detection sensitivity. In this review, we first illustrate the physical principle of TENOM that utilizes the antenna function of a sharp probe to efficiently couple light to excitations on nanometer length scales. We then discuss the antennainduced enhancement of different optical sample responses including Raman scattering, fluorescence, generation of photocurrent and electroluminescence. Different experimental realizations are presented and several recent examples that demonstrate the capabilities of the technique are reviewed.

Techniques for physicochemical characterization of nanomaterials

“…The far-field imaging resolution of a conventional optical microscope is limited by the diffraction phenomenon of illuminating light, which is specified by the Rayleigh criterion (Hartschuh, 2008; Heinzelmann and Pohl, 1994). While visible light is used in conventional optical microscopes, any two point sources cannot be resolved if they are spatially separated by less than approximately 200 nm (Heinzelmann and Pohl, 1994).…”

“…By adapting the concept of confining the light field in Raman near-field scanning optical microscopy to overcome diffraction-limited resolution, a recently emerging technique, tip-enhanced Raman spectroscopy (TERS), utilizes an apertureless metallic tip instead of an optical fiber to gain the surface enhancement of the Raman signals (the SERS effect) (Ando et al, 2013; Hartschuh, 2008; Hayazawa et al, 2012; Wang and Irudayaraj, 2013). In contrast to conventional RS, SERS and TERS provide topological information of the nanomaterials, in addition to their structural, chemical and electronic properties, which conventional RS provides (Lee et al, 2013b; Popovic et al, 2011).…”

The origin of interferometric effect involving surface plasmon polariton in scattering near-field scanning optical microscopy

“…This ability of high resolution optical imaging has been applied to investigate optical interactions beyond the diffraction limit, including material identification [2], characterization of optical devices [3][4][5], and nanoscale spectroscopy [6][7][8]. The key of high resolution imaging in s-NSOM is the sharp tip used for measurements.…”

Silicon nitride grids are compatible with correlative negative staining electron microscopy and tip-enhanced Raman spectroscopy for use in the detection of micro-organisms

“…; Deckert‐Gaudig et al . ; Hartschuh ; Mauser and Hartschuh ). The laser‐induced plasmon resonance results in a strong boost in the electromagnetic field in close proximity around the tip‐apex leading to a Raman signal enhancement of all molecules within the probed sample volume by several orders of magnitude.…”

“…After localization of a particle of interest, the metal-coated tip is positioned above the particle, and a TERS spectrum can be acquired in a contact or noncontact mode. A sharp metal tip is crucial for reaching a high spatial resolution and for overcoming the relatively low sensitivity of conventional Raman spectroscopy through plasmon resonance induced in the metal nanoparticle at the apex by irradiation with a focused laser (Stockle et al 2000;Deckert-Gaudig et al 2008;Hartschuh 2008;Mauser and Hartschuh 2013). The laser-induced plasmon resonance results in a strong boost in the electromagnetic field in close proximity around the tip-apex leading to a Raman signal enhancement of all molecules within the probed sample volume by several orders of magnitude.…”