A combined imaging,microthermal and spectroscopic study of a multilayer packaging system

The effectiveness of a packaging solution for the pharmaceutical and food industry is dependent on the integrity of the constituent layers and the interfaces formed between them. The deconvolution and analysis of the many intimate layers found in packaging is analytically challenging, requiring techniques capable of identifying sub‐micron regions. Here we have characterized the chemical and physical nature of the layers in a multilayer packaging system along with the interfaces, using a combination of high‐resolution atomic force microscopy (AFM), microthermal analysis using scanning thermal microscopy (SThM), and Fourier transform infrared (FT‐IR) spectroscopy. In particular, localized thermal analysis is shown to reveal the thermal transitions of the individual layers, but it was found that care must be exercised when melting through one layer to the next, as this can result in overestimates of melting temperatures of the underlying layer due to excess power loss from the SThM probe to the already molten top layer surrounding the probe. Copyright © 2004 John Wiley & Sons, Ltd.     

Lamellar structure in heat-treated polyethylene. A Raman spectroscopic study

Measurement of the low frequency Raman spectrum of polyethylene affords a method of following the effects of sample deformation on lamellar structure and of the process of annealing on lamellar thickness.     

A Raman spectroscopic study of photoluminescent porous silicon fibres

Porous silicon fibres are obtained from the topmost layers of porous silicon prepared by anodically etching p-type silicon–silicon epitaxial wafers, and exhibite, like black porous silicon, very intense light emission at room temperature under UV or visible laser excitation. The new material was characterised using several techniques in particular Raman spectroscopy. Silicon fibre is shown to be porous and highly ordered. A reversible thermal effect on the Raman characteristics of silicon fibre as well as on those of porous silicon is observed and is correlated with the change in the hole sizes of these materials and suggests a tuning method to reversibly change the band gap and other physical properties.     

AlGaN外延薄膜材料的椭圆偏振光谱研究

对蓝宝石衬底上生长的一系列AlxGa1-xN薄膜进行了椭圆偏振光谱研究,得到了薄膜的厚度以及245～1000nm的光学常数;通过有效介质模型计算出Al组分;随着Al组分的增加,折射率n下降,吸收边蓝移,与透射光谱结果一致。     

A spectroscopic study of vanadium-phosphate glasses containing vanadium chloride

The optical properties of vanadium-phosphate glasses containing various amounts of (V₂O₅)₅₀(P₂O₅)_50–x (VCl₃) _x , wherex = 0.05, 0.06, 0.08 and 0.1, were measured as a function of VCl₃ content. It is found that by adding VCl₃ to the melt when the glass is formed, the added chlorine which acts as an oxidizing agent alters the ratio of concentration of vanadium ions and thus the absorption coefficient. Data on absorption in this study show that the power law,() =B() –E ₀) ⁿ / is best followed forn = 3, and the absorption is solely due to vanadium oxide. Furthermore, the infrared absorption spectra of this system were investigated in the wave number range 400 to 4600cm^–1. The addition of VCl₃ to the vanadium-phosphate glasses does not seem to introduce any new absorption band in this range as compared with the spectrum of a pure vanadium-phosphate glass. Furthermore, no significant difference in the absorption spectra was observed by annealing the V₂O₅-P₂O₅ glasses up to 200° C.     

Nanosecond and femtosecond mass spectroscopic analysis of a molecular beam produced by the spray-jet technique

The spray-jet molecular beam apparatus enabled us to produce a molecular beam of non-volatile molecules under high vacuum from a sprayed mist of sample solutions. The apparatus has been used in spectroscopic studies and as a means of molecular beam deposition. We analyzed the molecular beam, consisting of non-volatile, solvent, and carrier-gas molecules, by using femtosecond- and nanosecond- laser mass spectroscopy. The information thus obtained provided insight into the molecular beam produced by the spray-jet technique.     

Optical properties and switching of a Rose Bengal derivative: A spectroscopic ellipsometry study

Optical properties in terms of the complex-valued dielectric function were determined for spin-coated films of a Rose Bengal derivative using variable angle of incidence spectroscopic ellipsometry in the visible and infrared wavelength regions. In addition, the thickness and roughness of the films were determined and related to the solution concentration of Rose Bengal. Switching between two different oxidation states of the Rose Bengal derivative was investigated. The two states were chemically induced by exposure to vapors of hydrochloric acid and ammonia, respectively. A substantial and reversible change of the optical properties of the films was observed.     

A study of internal stresses produced as a result of lubricated reversing friction

New experimental data on internal stresses produced in steel surface layers as a result of reversing friction in the presence of various lubricants are reported showing that the addition of organic alcohols to oil affects friction and friction-induced internal stresses, and that the use of oleic acid as a lubricant additive destroys the effect of alternating the direction of friction and leads to radical changes in the magnitude and distribution of internal stresses of the first kind.We would like to convey our thanks to Academician P. A. Rebinder and Professor S. Ya. Veiler for their valuable advice and interest in this work.     

A nuclear emulsion study of transition radiation

Durand's model for the production of transition radiation has been applied to the case of nuclear emulsion. It is found that, at Lorentz factors in the range 10² to 10⁵, the ionization along a track should not saturate at the plateau value, but should increase logarithmically with increasing Lorentz factor. Measurements of grain densities for identified muon and electron tracks are in agreement with this prediction.     

A study of macroliquation in solidification of a thin strip of a binary mixture produced by continuous casting

This is a study of the trends in macroliquation of an impurity in continuous casting of a thin strip produced of a binary mixture. Special attention is paid to analysis of the effect of forced convection, interdendrite filtration, diffusion, and the rate of drawing on redistribution of the impurity. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2, pp. 254–262, March–April, 1998.     

Coherent and incoherent components of a synchrotron radiation spot produced by separate capillaries

We discuss soft-x-ray focusing properties of separate capillaries. It is shown that a nonnegligible fraction of the synchrotron radiation beam transmitted by the capillary is modal. Experimental and theoretical data are discussed to explain the superposition pattern of x rays in the focal plane due to the interference phenomena of electromagnetic radiation propagating through separate capillaries.     

A study of damage in composite panels produced by hypervelocity impact

A phenomenological observation of the damage in graphite fiber (AS4/3501-6) composite panels caused by hypervelocity impact was made in this study. The panels have a nominal thickness of 2.54, 4.83, 6.6 and 17 mm. The impacts were made with nylon and aluminum projectiles of dimension 1.75 mm (dia) × 1.88 mm (length) with velocity from 3–7.5 km/sec. It was observed that the damage in the plate was caused by multiple breakage and delamination of the laminae and matrix material. The crater or hole area in all panels are approximately 7 to 9 times the area of projectiles for the velocity range used in the testing. The area of multiple breakage and delamination of layers in the panels are much larger than the corresponding crater or hole area, and they increase with the panel thickness and impact velocity.     

Thermal stability of PMMA-fullerene C60 nanocomposite: A spectroscopic study

Molecular mechanisms responsible for a decrease in the thermal stability of poly(methyl methacrylate)-fullerene C₆₀ nanocomposite in comparison to the pure polymer have been studied using a combination of spectroscopic techniques.     

Electron microscopy of defect clusters produced by radiation damage

The methods of characterization of different types of radiation-induced defect clusters bytem have been reviewed. Point defects produced in irradiated materials agglomerate in two or three dimensional clusters to reduce the strain energy associated with them. Two-dimensional clusters assume the configuration of vacancy or interstitial type dislocation loops which can be resolved if the size of the loops is large compared to the extinction distance associated with the imaging reflection. The small loops give rise to a black dot contrast under the kinematical and a black-white contrast under the dynamical imaging conditions. The method of characterization of dislocation loops which include the determination of the nature of the loop, the Burgers vector and the loop plane normal is discussed taking examples from the work done on the ion irradiated Ni₄Mo samples. A summary of available experimental results on the characterization of dislocation loops in different metals and alloys having fcc, bcc and hcp structures is presented. The contrast from stacking fault tetrahedra which form in some fcc metals and alloys after a certain degree of annealing is also discussed. The optimum conditions for imaging three-dimensional clusters or voids are derived on the basis of the contrast theory proposed for such defects. Special reference is made to the usefulness of “through focus analysis” in the imaging of very small cavities (with diameters as small as about 10 Å). It is shown that the formation of disordered zones resulting from displacement cascades in the ordered matrix can be utilized in determining the shape and the volume of cascades in the virgin state. The importance of different contributing factors like the strain contrast and the structure factor contrast in producing the overall contrast from the disordered zones is discussed. Detailed observations on the shape of the disordered zones are shown to be important to establish the occurrence of the replacement collision sequence and the formation of sub-cascades.     

Infrared spectroscopic study of natural materials

Infrared photothermal beam deflection spectroscopy (PBDS) was used to examine a variety of naturally-occurring materials having greatly different textures as well as greatly different chemical and physical properties. The diverse materials include oil shale, uintaite, fossil wood, narwhal tusk ivory, and geyser deposits. All were studied essentially without requiring the use of the time-consuming, often difficult ‘sample preparation’ procedures which are nearly always needed for the infrared examination of solids; the need of devising special sample preparation methods for highly unusual materials is obviated.     

Stress-induced crystal-to-crystal transformations in high-density polyethylene-layered silicate nano-composites: a spectroscopic study

High-density polyethylene (HDPE)-clay nano-composites have been prepared using the melt intercalation technique. Organically modified montmorillonite at various loadings (0.5--7%) was used as a nano-additive. Fourier transform infrared spectroscopy (FT-IR) was utilized for the first time to monitor the stress-induced crystal-to-crystal transformations of the polyethylene matrix with respect to the clay loading as well as to the degree of mechanical strain. In addition, polarized infrared measurements revealed information on both the orientation and the stress-induced distortion of the crystals. It was concluded that the crystal-to-crystal transformations are hindered by the presence of the clay, which also prevented the crystals from orienting even at low clay loadings (1%). Finally, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements confirmed the presence of the stress-induced crystalline structures in agreement with the infrared measurements.     

Optical properties of gold island films—a spectroscopic ellipsometry study

Metal island films of noble metals are obtained by deposition on glass substrates during the first stage of evaporation process when supported metal nanoparticles are formed. These films show unique optical properties, owing to the localized surface plasmon resonance of free electrons in metal nanoparticles. In the present work we study the optical properties of gold metal island films deposited on glass substrates with different mass thicknesses at different substrate temperatures. The optical characterization is performed by spectroscopic ellipsometry at different angles of incidence and transmittance measurements at normal incidence in the same point of the sample. Fitting of the ellipsometric data allows determining the effective optical constants and thickness of the island film. A multiple oscillator approach was used to successfully represent the dispersion of the effective optical constants of the films.