We have developed a new easy-to-use probe that can be used to combine atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). We show that, using this device, the evanescent field, obtained by total internal reflection conditions in a prism, can be visualized by approaching the surface with the scanning tip. Furthermore, we were able to obtain simultaneous AFM and SNOM images of a standard test grating in air and in liquid. The lateral resolution in AFM and SNOM mode was estimated to be 45 nm and 160 nm, respectively. This new probe overcomes a number of limitations that commercial probes have, while yielding the same resolution.Scanning probe microscopy (SPM) instruments are widely recognized as valuable tools for characterizing physical, chemical, electrical, electrochemical and optical properties of materials at the nanometer scale. Atomic force microscopy (AFM), for example, is routinely used to map the surface topography with a resolution well beyond the optical limit, both in gaseous and liquid environments [1]. By replacing the standard AFM cantilever with a tipped glass fiber, one can then equip the instrument with scanning near-field optical microscopy (SNOM) capabilities. The latter can provide information on the optical field emerging from the surface of the sample with a lateral resolution of a few tens of nanometers [2,3,4]. The combination of AFM and SNOM has found applications in many fields, including cell biology and single molecule experiments [5,6].
A fast high-resolution screening method for reactive surfaces is presented. Atomic force microscopy (AFM) and surface-enhanced Raman spectroscopy (SERS) are combined in one method in order to be able to obtain both morphological and chemical information about processes at a surface. In order to accurately align the AFM and SERS images, an alignment pattern on the substrate material is exploited. Subsequent SERS scans with sub-micron resolution are recorded in 30 min per scan for an area of 100 × 100 µm and are accompanied by morphological information, supplied by a fast AFM, of the same area. Hence, a complete reactivity overview is obtained within several hours with only a monolayer of reactant. To demonstrate the working principle of this method, a SERS substrate containing the alignment pattern and silver nanoparticle aggregates as catalytic sites is prepared to study the photo-catalytic reduction of p-nitrothiophenol ( p-NTP).
Summary Fibre‐top probes are self‐aligned, all optical devices obtained by carving a cantilever on top of a 125‐μm diameter single‐mode optical fibre. In this paper, we show that this design can be adapted to smaller fibres as well. We evaluated the performance of a 20‐μm diameter probe in contact mode atomic force microscopy (AFM) and that of a 50‐μm diameter probe in nanoindentation measurements. AFM images proved to be accurate both in air and water, although some distortion was observed because of the mechanical bending of the fibre during scanning. Indentation curves resembled those obtained with larger devices. The maximum indentation depth, however, is limited by the small dimensions of the cantilever.
Today, vertical cavity surface emitting lasers (VCSELs) are used in many high-end applications, for which the laser lifetime is a critical parameter. Changes in the spatial distribution of the various emission modes of the VCSEL can be used as an early sign of device degradation, enhancing the speed and detail of failure mode analysis. We have developed a ferrule-top combined atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) probe that can be used to analyze the transverse mode pattern of the 850 nm radiation at a <200 nm spatial resolution. During accelerated lifetime testing, the newly developed method shows that small local changes in the optical output can already be detected before any sign of device degradation is observed with conventional methods.
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