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A hybrid conventional inverted/scanning near-field optical microscope (Inverted/SNOM) has been obtained, by coupling an Olympus IX-70 optical microscope with a SNOM head to combine the versatility and ease of use of the conventional microscope with the high-resolution and three-dimensional reconstruction obtainable with the SNOM technique. The head can be run in shear or tapping mode and is optimized to characterize soft, biological samples including living cells in physiological environment by including the SNOM in a cylindrical chamber that insulates it from the external noise, while maintaining a controlled temperature and atmosphere. Applications in the fields of biology and material science are presented.

With confocal Raman microscopy, detailed images of the three-dimensional structure of thick samples (such as porous materials, aggregated nanoparticles etc.) could be readily acquired and visualized with sub-micron resolution. However, confocal Raman microscopy is not a panacea, especially for the studies of nanostructures, mainly because of diffraction limits for the optical resolution. The spatial resolution of Raman systems employing traditional optical microscopes is limited to approximately the wavelength of the light (about 0.5 µm), because both the illuminating laser light and the Raman scattered light are collected in the optical far-field (i.e. many wavelengths of light away from the scattering material). We will describe a new setup for nano-Raman experiments by using the fiber-optic scanning probe of a Scanning Near Field Optical Microscope (SNOM). The collected Raman signal in this near-field geometry reaches spatial resolutions at the level of tens of nanometers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Scanning near-field optical microscopy (SNOM or NSOM) is the technique with the highest lateral optical resolution available today, while infrared (IR) spectroscopy has a high chemical specificity. Combining SNOM with a tunable IR source produces a unique tool, IR-SNOM, capable of imaging distributions of chemical species with a 100 nm spatial resolution. We present in this paper boron nitride (BN) thin film images, where IR-SNOM shows the distribution of hexagonal and cubic phases within the sample. Exciting potential applications in biophysics and medical sciences are illustrated with SNOM images of the distribution of different chemical species within cells. We present in this article images with resolutions of the order of λ/60 with SNOM working with infrared light. With our SNOM setup, we routinely get optical resolutions between 50 and 150 nm, regardless of the wavelength of the light used to illuminate the sample.

The advent of scanning near-field optical microscopy (SNOM) has augmented at a microscopic level the usefulness of optical spectroscopy in the region between 300 nm and 10 mum. Two-dimensional imaging of chemical constituents makes this a very attractive and powerful new approach. In this paper we show SNOM results obtained in several geometrical configurations on boron clusters in silicon, Li clusters embedded in a LiF sample and BN growth on silicon. We also show some results on the wavelength dependence of the reflectivity (R) in the near infrared (IR) of biological cells in liquid environment with the observation of the local fluorescence. The SNOM images revealed features that were not present in the corresponding shear-force (SF) images and which were due to localized changes in the bulk properties of the sample. The size of the smallest detected features clearly demonstrated that near-field conditions were reached both in the visible and infrared region. (C) 2004 Elsevier B.V. All rights reserved.

High resolution infrared imaging of thin films and biological systems is one of the most challenging experimental problems in contemporary science and technology. In this work, we have for the first time successfully tested a novel high resolution approach, based on a spectroscopic version of scanning near-field optical microscopy (SNOM). The coupling of the Vanderbilt Free Electron Laser tunable infrared radiation to SNOM apparatus enabled us to clearly reveal different chemical constituents on a growth medium for biofilm. The images were obtained by SNOM detection of reflected 6.95 μm photons, corresponding to the stretch absorption of sulfur and nitrogen compounds, constituents of the growth medium. We attained a lateral resolution of 0.2 μm (λ/35), well below the diffraction limit of classical microscopy.

Chalcogenide glass optical fibers were fabricated into functional apertured probes for near field scanning infrared microscopy. Probe fiber tips were chemically etched and aluminum coated for the purpose of simultaneously collecting near field shear force and optical signals. Surface topography and infrared optical reflectivity data were obtained using the tips in a scanning near field microscope while illuminating an integrated microcircuit with the output from a free electron laser operating at a λ of 4.7 μm. Approximately 25 nm topographical and 100 nm optical lateral resolution were observed.

The study of semiconductor interfaces and of solid interfaces in general requires novel instrument capable to investigate the lateral fluctuations of properties on a microscopic scale. We present the first result of a major effort in that framework, whose main objective is the exploitation of the unique characteristics of free electron laser (FEL) infrared sources. The background was provided by our previous development of FEL-based techniques to measure interface barriers with high accuracy and reliability. Quite recently, we were able to implement similar investigations with high lateral resolution. The key elements were the use of a small-tip optics fiber and its coupling with a scanning module; in this way, we achieved and verified the condition of near-field microscopy including a lateral resolution much below the wavelength value. Our discussion includes a presentation of the first scanning near-field optical microscopy (SNOM) images obtained with an FEL and data on small and microscopic-scale fluctuations of semiconductor interface barriers. The likely development of this exciting new field will also be discussed, in particular considering the new proposals for powerful FELs in the low-wavelength spectral range.

We have fabricated and tested infrared scanning near-field optical microscope (IR-SNOM) probe tips made from singlemode chalcogenide fiber. The process used to create the tips was similar to conventional micropipette-puller techniques, with some modifications to allow for the lower melting temperature and tensile strength of the chalcogenide fiber. SEM micrographs, showing tips with sub-micrometer physical dimensions, demonstrate the feasibility of this process. Topographical data obtained using a shear-force near-field microscope exhibits spatial resolution in the range 80-100 nm. Optical data in the infrared (near 3.5 mu m), using the probe tips in collection mode, indicates an optical spatial resolution approximately lambda/15. (C) 1999 Published by Elsevier Science B.V. hll rights reserved.

This contribution presents an application of scanning near-field optical microscopy to the characterization of semi-conductors. It is based on the photocurrent mapping of a patterned Au/GaAs structure (Schottky barrier) under local illumination by the nanosource. The results obtained with different wavelengths, metallized or dielectric probes and different bias voltages exhibit photocurrent variations independent of the topography and induced by interface defects. Finally, from this study of a patterned planar structure, we propose a method to determine the mean free path of the charge carriers in the volume.

A multipurpose scanning near field optical microscope (SNOM) operating at ambient pressure is described with the aim of characterizing the inner parts of biological molecules and any semiconductor or metal microstructure. Therefore, in addition to the requirements of reliability and mechanical stability we have carefully considered analyzing a sample with all available geometries for input/output of photons, in order to get as much information as possible. The SNOM unit consists of two separable cylindrical supports; the lower one contains the sample holder mounted on top of a piezoelectric scanner which is contained in a motor controlled x-y-z stage. A piezo-modulated stretched optical fiber with a few tens of nanometer pinhole and a shear-force apparatus mounted inside the top cylinder allow for topography measurements. The reflectivity of the sample can be measured by applying different methods: the sample can be illuminated on top by an external source, as well as by the optical fiber used for the det...

A scanning tunneling (STM)‐atomic force microscope (AFM) operating at ambient pressure is described. A sound‐isolated chamber contains the STM‐AFM unit; the chamber can be evacuated or filled with inert gas, after the sample and tip (lever) are loaded, in order to reduce contamination on the sample. The STM‐AFM unit consists of two separable cylindrical supports whose lower one contains the sample holder mounted on top of a piezoelectric scanner (movements 6×6×3 μm) that is contained in a motor controlled x–y–z stage (movements 8×8×1 mm). An I/V converter preamplifier for STM operation and a laser deflection circuit for AFM operation are separately mounted inside two different top cylinders. The STM top cylinder can be changed with the AFM one without removing the sample thus giving the possibility of looking at the same sample with STM and AFM. An optical microscope that can reach 120 enlargements allows us to position the tip or the lever on particular regions of the sample through the motor drives. A c...

Surface differential reflectivity measurements have been carried out for a cleaved CdTe(110) surface. A broad structure centered around 3.5 eV has been found and been deconvolved into three main spectral features at 2.9, 3.5, and 3.9 eV. Our analysis ascribes these peaks to optical transitions at the \ensuremath{\Gamma}, X, and X' points of the surface Brillouin zone, respectively. The oxidation process of the surface was analyzed and the sticking coefficient of excited molecular oxygen was estimated.

The innovative potential of a non-commercial apparatus for simultaneous in situ Atomic Force Microscopy (AFM) and Energy Dispersive X-ray Reflectometry (EDXR) measurements is presented. A comparison between the two techniques, probing the samples surface in the direct and the reciprocal spaces, respectively, provides a deeper inspection in the surface morphology. Additionally, X-ray Reflectometry applied to films gives joint information on the surface and bulk morphology. The results on a gas sensing film demonstrate how simultaneous time-resolved AFM/EDXR allow the film surface/bulk morphology to be monitored, offering a unique tool to study the active materials in film-based technological devices in operating conditions.

First experiments at the Vanderbilt free electron lasers measured the local reflectivity of a PtSi/Si system. The reflectivity in the scanning near-field optical microscope images revealed features that were not present in the corresponding shear-force (topology) images and which were due to localized changes in the bulk properties of the sample. The size of the smallest detected features clearly demonstrated that near-field conditions were reached. The use of different photon wavelengths (0.653, 1.2, and 2.4 mu m) enabled us to probe regions of different depth. (C) 1998 American Institute of Physics.

In this paper we present chemically highly resolved images obtained with Scanning Near-field Optical Microscopy (SNOM) coupled with an Infrared (IR) Free Electron Laser (FEL) at Vanderbilt University, Nashville, USA. Main principles governing SNOM imaging as well as essential components of the experimental setup are described. Chemically resolved images showing the distribution of different phases within the boron-nitride films are presented. Universal character of the experiment and its huge potential applications in biophysics and medical sciences domain are illustrated with highly resolved SNOM images of pancreatic cells.

Scanning near-field optical microscopy (SNOM) makes it routinely possible to overcome the fundamental diffraction limit of standard (far-field) microscopy. Recently, aperture-based infrared SNOM performed in the spectroscopic mode, using the Vanderbilt University free electron laser, started delivering spatially-resolved information on the distribution of chemical species and on other laterally-fluctuating properties. The practical examples presented here show the great potential of this new technique both in materials science and in life sciences. (C) 2004 Elsevier B.V. All rights reserved.

The early stages of Sb films deposited at room temperature on Si(100)2×1 surfaces have been investigated by angle-integrated and angle-resolved Auger spectroscopy. A comparison between the experimental results and the predictions of simple deposition models indicates that the growth of the Sb film proceeds by island formation. Without any annealing, a uniform overlayer never develops up to films 4 nm thick

Hydrogen chemistry in thin films and biological systems is one of the most difficult experimental problems in today's science and technology. We successfully tested a novel solution, based on the spectroscopic version of scanning near-field optical microscopy (SNOM). The tunable infrared radiation of the Vanderbilt free electron laser enabled us to reveal clearly hydrogen-decorated grain boundaries on nominally hydrogen-free diamond films. The images were obtained by SNOM detection of reflected 3.5 microm photons, corresponding to the C-H stretch absorption, and reached a lateral resolution of 0.2 microm, well below the lambda/2 (lambda = wavelength) limit of classical microscopy.

We studied the fully-formed (80 angstroms) Pt/GaP and (140 angstroms) Au/GaAs interfaces by scanning near-field optics microscopy, internal photoemission, atomic force microscopy, and by x-ray photoemission electron microscopy. These complementary techniques enabled us to correlate the spatial variations of the diodes transport properties with the chemical and topographic inhomogeneities of the buried metal-semiconductor interfaces.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A hybrid conventional/scanning near-field optical microscope is presented. The instrument is obtained coupling an Olympus IX-70 inverted optical microscope with a SNOM head, to combine the versatility and ease of use of the conventional microscope with the high-resolution and three-dimensional reconstruction achieved by the SNOM. The head can be run in shear or tapping mode and is optimized to characterize soft, biological samples including living cells in physiological environment by including the SNOM in a cylindrical chamber that insulates it from external noise, while maintaining a controlled temperature and atmosphere. © 2010 IOP Publishing Ltd.

We present an apparatus for controlling the deposition of thin films. The apparatus is based on a quartz resonator whose frequency is controlled digitally by a computer. Temperature variations of the quartz during the evaporation process, attributed to the exothermic heat of condensation and radiation heating from the evaporation source, are compensated. A very stable deposition rate and a good film thickness evaluation are obtained.

We fabricate scanning near-field optical microscope (IR-SNOM) probe tips made from singlemode chalcogenide fiber and test them using a standard SNOM setup and free-electron laser. SEM micrographs, showing tips with submicrometer physical dimensions, demonstrate the feasibility of the thermal micropipette puller process used to create the tips. Topographical data obtained using a shear-force near-field microscope exhibit spatial resolution in the range of 80 to 100 nm. Optical data in the IR (near 3.5 $\mu$m), using the probe tips in collection mode, indicate an optical spatial resolution of approximately $\lambda/15$.

SUMMARY A scanning tunnelling microscope working in air with good atomic resolution is described. Atomic corrugation of graphite samples cleaved in air has been observed with a lateral resolution considerably less than 1 A. The height of the potential barrier is measured as a function of the time the system tip-sample is exposed to air. An explanation for the observed giant corrugation is given.

Infrared scanning near-field optical microscopy (IR-SNOM) is an extremely powerful analytical instrument since it combines IR spectroscopy's high chemical specificity with SNOM's high spatial resolution. In order to do this in the infrared, specialty chalcogenide glass fibers were fabricated and their ends tapered to generate SNOM probes. The fiber tips were installed in a modified near-field microscope and both inorganic and biological samples illuminated with the tunable output from a free-electron laser located at Vanderbilt University. Both topographical and IR spectral images were simultaneously recorded with a resolution of similar to 50 and similar to 100 nm, respectively. Unique spectroscopic features were identified in all samples, with spectral images exhibiting resolutions of up to lambda/60, or at least 30 times better than the diffraction limited lens-based microscopes. We believe that IR-SNOM can provide a very powerful insight into some of the most important biomedical research topics.

We used a combination of internal photoemission and of near-field optical microscopy (SNOM) to study the lateral Variations in solid interface properties such as energy barriers and electron-hole recombination. Ln particular we investigated the fully formed Pt-GaP, Au-GaAs, Au-SiNx-GaAs and PtSi-Si Schottky barriers. Our approach enabled us to measure large lateral variations in the photocurrent with spatial resolution on the nanometric scale. Due to the ability of SNOM to supply parallel topographic information, we observed photocurrent variations from zone to zone that only correlated in a few cases with local variations in surface morphology. We assigned the uncorrelated fluctuations to local variations in the interface stoichiometry, the presence of interface states induced by the metallic overlayer and to defect states at the junction. Furthermore, by tuning the photon energy and applied bias we were able to measure the surface distribution of the diffusion length.

First experiments of coupling a free electron laser to a scanning near-field optical microscope (SNOM) are presented. To address the question of how important such spectroscopy can be for near-field infrared microscopy, we acquired images of the same region of the sample under investigation at several photon wavelengths. SNOM reflectivity images revealed features that were not present in the corresponding shear-force (topology) ones and which were due to localized changes in the bulk properties of the sample. Optical data in the infrared (near 3.5 mu m), using the probe tips in collection mode, indicates an optical spatial resolution well below the classical limit of lambda/2.

The advent of scanning near-field optical microscopy (SNOM) has augmented at the microscopic level the usefulness of IR spectroscopy. Two-dimensional imaging of chemical constituents makes this a very attractive and powerful new approach. In this paper we present SNOM results on boron-doped silicon and on biological growth medium by means of shear-force, reflectivity and photocurrent measurements. Such experiments allowed us to identify boron clusters embedded in silicon and the distribution of growth medium constituents with a lateral resolution well below the diffraction limit. (C) 2003 Elsevier B.V. All rights reserved.