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Scattering scanning near-field optical microscopes (s-SNOMs) based on pseudoheterodyne detection and operating at ambient conditions typically suffer from instabilities related to the variable optical path length of the interferometer arms. These cause strong oscillations in the measured optical amplitude and phase comparable with those of the signal and, thus, resulting in dramatic artifacts. Besides hampering the comparison between the topography and the optical measurements, such oscillations may lead to misinterpretations of the physical phenomena occurring at the sample surface, especially for nanostructured materials. Here, we propose a stabilizing method based on interferometer phase control, which improves substantially the image quality and allows the correct extraction of optical phase and amplitude for both micro- and nanostructures. This stabilization method expands the measurement capabilities of s-SNOM to any slowly time-dependent phenomena that require long-term stability of the system. We envisage that active stabilization will increase the technological significance of s-SNOMs and will have far-reaching applications in the field of heat transfer and nanoelectronics.

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...

Tungsten tips obtained through electrochemical etching have been characterized by scanning electron microscopy, scanning Auger microscopy, and scanning tunneling microscopy. While such tips resulted to be very sharp, a thick oxide layer (∼10 nm) is present at the apex. High‐vacuum annealing at 1800 K removes most of such oxide.

A new implementation of a shear-force microscope is described that uses a shear-force detection system to perform topographical imaging of large areas (~1×1 mm2). This implementation finds very interesting application in the study of archeological or artistic samples. Three dc motors are used to move a sample during a scan, allowing the probe tip to follow the surface and to face height differences of several tens of micrometers. This large-area topographical imaging mode exploits new subroutines that were added to the existing homemade software; these subroutines were created in Microsoft VISUAL BASIC 6.0 programming language. With this new feature our shear-force microscope can be used to study topographical details over large areas of archaeological samples in a nondestructive way. We show results detecting worn reliefs over a coin.

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.