Search results for "Optical microscope"

Towards the origin of the shear force in near-field microscopy

2001

The shear force from a gold or a graphite sample acting on an approaching near-field optical probe is studied in detail. The adiabatic and dissipative contributions to the force are clearly distinguished by monitoring the amplitude as well as the phase of the tip vibration when the tip approaches the surfaces. We also take into account that not only the damping and the resonance frequency but also the mass of the system changes when the tip approaches the surface. The relative strength of the contributions to the force varies differently but characteristically with the distance of the two samples, starting at a much larger distance in the case of graphite. The adiabatic contribution is lar…

1988

Structure et proprietes thermodynamiques de polyamides rigides portant ces groupes lateraux flexibles

Microchemical surface analysis of historic copper-based coins by the combined use of FIB-FESEM-EDX, OM, FTIR spectroscopy and solid-state electrochem…

2019

[EN] A multi-technique strategy, including microscopy, spectroscopic and electrochemical techniques, is proposed to study thin corrosion layers that form on the surface of historic copper-based coins. An accurate characterisation of this external corrosion layer is important for selecting a suitable conservation and/or restoration treatment. For this purpose, a series of copper-based coins from different historical periods and provenances, which mainly exhibited atmospheric corrosion, was analysed. The morphology of the corrosion layer and the upper core of coins was studied in trenches done on coin surfaces with a focused ion beam gun, coupled to a field emission scanning electron microsco…

On the response of flax fiber reinforced composites under salt-fog/dry conditions: Reversible and irreversible performances degradation

2022

Abstract Despite their scarce resistance to humid or wet conditions, natural fiber reinforced composites (NFRCs) seem to be able to partially recover their performances under discontinuous exposition to marine environment. To investigate this peculiarity, flax fiber reinforced composite was at first subjected to salt-fog spray condition at 35 °C for 15 and 30 days, respectively, and then stored in ‘‘dry” condition (i.e., 50% R.H. and 22 °C) between 0 and 21 days. The performances evolution was evaluated through flexural tests, water uptake and contact angle measurements. Moreover, the morphology of fractured mechanical samples was examined by using 3D optical microscope and scanning electro…

X-ray study of LB multilayers of cadmium soaps in the vicinity of the break up point

1991

Temperature dependent SAXS measurements were carried out on multilayers of two different salts, cadmium palmitate (hexadecanoate) and behenate (docosanoate). The pattern characteristic of layer structure disappears at a transition temperature well below the bulk melting point in both cases. Examination by means of optical microscopy shows that the LB films break up at a temperature close to this transition. Measurements in its vicinity demonstrate that over a certain temperature range just below the transition a second set of peaks arises in the diffraction pattern. During this transition region of about 3 °C width two d-spacings for both salts were found, suggesting the simultaneous existe…

Preparation and Thermal Behavior of Freely-Suspended and Transferred Films Composed of a Single Compound, the Liquid Crystal 707PP

1991

We have recently introduced a new method for the preparation of ultrathin smectic films on solid supports by transferring freely-suspended liquid-crystalline films [1, 2]. Here we report on the preparation, structural properties and thermal behavior of freely-suspended and transferred films of 2-(4'-Heptyloxyphenyl)-5-heptylpyridine (707PP). Freely-suspended and transferred films were investigated using optical microscopy and X-ray diffraction. Both types of films exhibit reversible phase transitions comparable to bulk values.

Relative proportions of rutile and pseudo-brookite phases in the Fe(III)-TiO2 system at elevated temperature

1997

Abstract The Fe(III)-TiO2 system has been studied at T ≥ 1023 K in the range of concentration 2–10 at.% of iron by powder X-ray diffraction, transmission and scanning electron microscopy, and optical microscopy. The relationship between the relative proportions of the TiO2 rutile phase and the pseudo-brookite phase Fe2TiO5, has been investigated in powder samples. Single crystals of pure rutile and rutile doped with 0.5 at.% of iron have been examined to elucidate the microstructures found in the powders. The results suggest that a low degree of solid solubility exists and that doped crystals contain planar faults on 101 planes.

Uniaxial Alignment of Polycyclic Aromatic Hydrocarbons by Solution Processing

2005

The self-organization of two polycyclic aromatic hydrocarbons with different aromatic core sizes, dodecylphenyl-substituted hexa-peri- hexabenzocoronene and an extended disk consisting of 96 carbon atoms 6-fold-alkyl-substituted, on the surface from solution has been investigated. Highly ordered surface layers of both materials could be obtained by the zone-casting technique, despite an apparently low self-organization in drop-cast films. The zone-cast films revealed high macroscopic uniaxial orientation of the columns with a molecular edge-on arrangement on the glass support as confirmed by polarized optical microscopy, UV-vis measurements in polarized light, high-resolution transmission e…

Theoretical study of an absorbing sample in infrared near-field spectromicroscopy

2004

Abstract This paper is devoted to study the near-field spectrometry in the infrared spectral range. To understand the behavior of the infrared light diffracted by an object, numerical calculations have been carried out with Fourier Modale (FM) method within R-matrix algorithm. We consider the case of three-dimensional system including a translational symmetry in one direction, where is included an homogenous layer in which is buried an absorbing object. Using an optical near-field analysis and by calculating the electric field intensity distribution, both of the thickness effect and the lateral size of the absorbing sample are investigated. It is found that the distribution of the intensity…

SNOM study of ferroelectric domains in doped LiNbO3 crystals

2009

Abstract This work shows a study of the periodic ferroelectric domains formed in LiNbO3 crystals doped with rare earths by means of scanning near field optical microscopy (SNOM) technique. It has been observed periodic structures associated with ferroelectric domains with an unexpected high value of the optical contrast working under reflectance SNOM mode. From Raman-Nath diffraction patterns, a refractive index modulation of Δ n ∼ 1 0 − 4 has been calculated. These results were correlated with the ferroelectric periodic domains obtained by the SNOM technique. A light waveguide effects along the ferroelectric domains is suggested to explain the high reflectance contrast observed in SNOM exp…