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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.

Human HaCaT cells, exposed for 24 h to a 1 mT (rms) 50 Hz sinusoidal magnetic field in a temperature-regulated solenoid, suffer detectable changes in their biochemical properties and shapes. By using infrared wavelength-selective scanning near-field optical microscopy, we observed changes in the distribution of the inner chemical functional groups and in the cell morphology with a resolution of 80-100 nm.

The interaction of the cytotoxic metals cadmium, zinc, and lead with pancreatic cells was studied by atomic force/lateral Force microscopy (AFM/LFM), an approach that provides both topographic (with nanometer scale lateral resolution) and chemical information on the membrane. Different morphological modifications of the overall cell shape and roughness took place as consequence of 100 μM metal-dependent treatment. Furthermore, after exposure to Cd(Cl2) and Zn(Cl2), but not Pb(Cl2), the LFM images revealed several areas of the cell's surface showing lateral friction contrasts that have been interpreted as marker of different alterations of the cell physiology induced by the metal loading. Thus, the coupling of LFM detection to topographic AFM characterization allows to distinguish, through a nondestructive and surface characterising approach, between different metal-induced cytotoxic effects on cells. In this framework, the role of the LFM as an important tool to discriminate between different alteration of a biological system has to be highlighted. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc.

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)

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.

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.

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...

We have designed and built a scanning tunneling microscope (STM) suitable for biological applications. A sound‐isolated chamber contains the STM unit; the chamber can be evacuated or filled with inert gas, after the sample and tip are loaded, in order to reduce contamination on sample and tip. The STM unit is mounted inside two separable cylindrical supports. The lower cylinder contains the sample holder mounted on top of a step‐motor controlled x‐y‐z stage, while the upper one contains the piezoelectric tip scanner. An I/V converter preamplifier mounted inside the x‐y‐z stage and a completely digitized feedback circuit, together with a full software package in UNIX X‐window environment and data processing, allow fast sample–tip approach and reduced acquisition time. Atomic resolution images of highly oriented pyrolytic graphite (HOPG) in air and reproducible large scan on a platinum grating are routinely obtained. Images of human liver ferritin deposited on an activated gold substrate have also been obta...

We studied the effect of the interaction of electromagnetic radiation with human keratinocytes (HaCaT), at low (50 Hz, 1 mT) frequency using both atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) techniques. AFM analysis showed modifications in shape and morphology in exposed cells, while SNOM indirect immunofluorescence analysis revealed an increase of segregation of β4 integrin (an adhesion marker) in the cell membrane of the same cells, suggesting that a higher percentage of the exposed cells shows a modified pattern of this adhesion marker.

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.

In the present study, carbon films were deposited by a pulsed laser deposition method. A C60 fullerene target has been irradiated by a frequency doubled Nd:YAG laser with a pulse duration of 7 ns. The carbon films grown on Si(111) substrates at different substrate deposition temperatures (30, 300 and 500 °C) were characterized by Raman, X-ray Photoelectron and X-ray Auger Electron Spectroscopies, Energy Dispersive X-Ray Diffraction, Scanning Electron and Atomic Force Microscopies, and Vickers microhardness technique. The composition, structure, morphology and mechanical properties of films were found to be strongly dependent on the substrate temperature. At 30 °C and 300 °C deposition temperature, superhard and hard diamond-like films have been obtained, respectively. In the case of 500 °C deposition, a hard film, composed of crystalline C60 and diamond-like carbon, has been prepared.

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.

The morphological changes induced in (RuPc)2 gas sensing thin films by hydration and de-hydration processes were investigated. Prior to this study a preliminary characterization was performed by conductivity measurements upon exposure to NO2 gas fluxes, to verify the electrical sensing response of the films. This response was correlated to the bulk morphological modification of the films. Subsequently, the effect of external moisture on the morphological stability of the films was addressed. This morphological characterization of the films was performed by using the energy dispersive X-ray reflectivity (EDXR) and atomic force microscopy (AFM) techniques, both ex situ and in situ, i.e. under operating conditions, during exposure of these films to 100% of relative humidity. The measurements allowed an accurate observation of both the surface morphology (i.e. its roughness obtained independently by EDXR and AFM). Moreover bulk evolution of the films was obtained by in situ EDXR and the morphological changes allowed to retrieve information on the water uptake dynamics. Moreover, the reversibility of the water/film interaction was studied and correlated to the sensing properties of the (RuPc)2.

The crucial requirement of device stability in the development of organic electronics was addressed. In particular, the nanoscale morphology of bulk heterojunction organic films for photovoltaic applications was studied by time-resolved energy dispersive X-ray reflectometry in synergy with atomic force microscopy analysis. A reorganization of the organic molecules in the film upon illumination was detected. The occurrence of two distinct processes (characterized by a reorganization of the blend bulk and an increase of its surface roughness, respectively) was revealed. Furthermore, the effect of the morphological instability on the device efficiency over time was quantified. Finally, the effect of thermal annealing treatments and of the choice of different cathodes was verified.

We report on the use of thermal annealing to improve the behavior of NO2 gas-sensing ruthenium phthalocyanine films at high temperatures. The approach used, based on the study of the effect of temperature on the film morphology, makes use of in situ energy dispersive X-ray reflectometry and atomic force microscopy. The results show that the morphological changes, induced by high working temperatures, strongly affect the material sensing ability. Furthermore, we demonstrate that the film morphology may be stabilized by thermal annealing treatments, thus enhancing the sensor performances in terms of response times and the capability to work at high temperatures.

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.

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.

Silicon and silicon nitride surfaces have been successfully terminated with carboxylic acid monolayers and investigated by atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). On clean Si surface, AFM showed topographical variations of 0.3-0.4 nm while for the clean Si3N4 surface the corrugation was around 3-4 nm. After material deposition, the corrugation increased in both samples with a value in topography of 1-2 nm for Si and 5-6 nm for Si3N4. The space distribution of specific chemical species was obtained by taking SNOM reflectivity at several infrared wavelengths corresponding to stretch absorption bands of the material. The SNOM images showed a constant contribution in the local reflectance, suggesting that the two surfaces were uniformly covered. (C) 2003 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

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.

We present several experimental results of imaging DNA on graphite. Images have been taken simultaneously in constant-current and gap-modulated mode. This way of imaging has been very helpful in order to discriminate between structures due to biological molecules and substrate artifacts. A possible way of using the tip to confirm this conclusion is shown.© (1993) 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 $\lambda/15$.

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.

A cell for biological samples that allows atomic force microscopy (AFM) observations in a controlled environment (air or gas or any liquid) is described. The cell is made of a modified Petri container and it is possible, through two inlet and outlet feedthroughs, to introduce an aqueous liquid during AFM observation thus directly visualizing the modifications induced on the biological specimen. Uncoated neurons and Escherichia Coli bacteria have been imaged in air and after introducing an aqueous liquid by contact-mode AFM: the microimages are similar and show a comparable resolution even though the force applied to the biological material is different.

A scanning tunneling microscope working in air with good stability at atomic resolution is described. Atomic corrugation of graphite samples cleaved in air has been observed with a lateral resolution considerably less than 1 A.