Total reflection X-ray photoelectron spectroscopy as a semiconductor lubricant elemental analysis method

A numerical simulation of total reflection X-ray photoelectron spectroscopy (TRXPS)

The influence of substrate absorbency on coating surface chemistry

A new shock sensor for liquids is described in this article which is suitable for precise shock Hugoniot compression curve measurement of water in the relatively low pressure region of ⩽1 GPa. The present method is based on the fact that the refractive index of water has a very large pressure dependence. A laser beam incident on the liquid–glass boundary from the proper angle of incidence is totally reflected at the interface. The condition of total internal reflection is violated if the refractive index changes instantaneously by shock compression. The shock target assembly was designed for a gas gun experiment based on the above concept. Two examples of the shock Hugoniot measurement data of water were given.

We report on a new experimental technique for monitoring laser-induced shock waves and thermal waves above the sample surface called total internal reflection based photothermal or photoacoustic deflection (TIR based PTD/PAD deflection). It is based on the changes in transmissivity of a prism which is operated near the condition of total internal reflection for a HeNe laser beam propagating parallel to the sample surface at a small distance. The HeNe laser beam is probing photoacoustic or photothermal waves originating from a sample surface due to interaction with a pulsed Nd:YAG laser beam. The method is compared with standard online detection techniques like scatter probe monitoring and plasma detection, and found to be a very sensitive and practical tool. It also showed its suitability for selectively monitoring several surfaces (e. g. front and rear surface) of optical components, and attributing the damage starting point. Therefore, the method might be used for monitoring of surface damage on laser crystals or valuable components. Keywords: photothermal deflection, photoacoustic deflection, laser damage, total internal reflection.

In conventional optics for light waves, the pioneering work by Goos-Hänchen in 1947 on the lateral shift (or displacement) of a light beam along the surface of a dielectric boundary under the condition of total reflection has stimulated a large number of studies. The key physics behind the Goos-Hänchen shift is the nature of wave interference. From the perspective of wave optics, the incident beam of a finite transverse width can be viewed as composed of plane wave components, each of which has a slightly different transverse wavevector. Each wave component, after the total internal reflection, undergoes a different phase shift, and the superposition of all the reflected wave components gives rise to the lateral shift of the intensity peak in the reflected beam.

Many types of polymers have been used for medical devices for blood contacting application. Polyurethanes have been determined to be one of the more blood-compatible. However, there is variability within types of polyurethanes and even within the same type of polyurethane as far as hemocompatibility. This variability stems in part from differences in processing aids, including waxes, which manufacturers add. An understanding of the surface chemical properties is essential for the determination of the hemocompatibility of polyurethanes. For this presentation, we describe analysis of the wax component of the surface of a polyurethane commonly used for extruded medical devices, Pellethane 2363 (Dow), by Fourier-transform infrared-attenuated total reflection (FTIR-ATR) and x-ray photoelectron spectroscopy (XPS), and the effect of its presence on the hemocompatibility of Pellethane. Solvent cleaned samples, demonstrating reduced amide processing wax component by the two techniques, are also evaluated for blood–surface interactions. Tubing samples are evaluated for hemocompatibility by exposure to human platelet/plasma solutions followed by analysis using scanning electron microscopy. There is a direct correlation between the amount of amide processing wax in Pellethane as determined by FTIR-ATR and XPS and the in-vitro hemocompatibility.

The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body.

In this paper we report computer calculations of the reflectivity of a hybrid nematic cell near the condition of total incernal reflection. The Berreman matrices method allows us to drop the approximations used in previous papers. In this way we get details about the interference pattern arising when the total internal reflection occurs inside the sample. We show how the reflectivity curve is affected by the director orientation which in a hybrid cell is essentially due to the boundary conditions. Our results suggest that measurements of this reflection pattern can give detailed information about the local director orientation.

A general strategy for the fabrication of nanoscopic light sources is presented. In these high-index-contrast materials, light is confined and its intensity is enhanced on the nanometer scale because of the large discontinuity of the electric field at high-index-contrast interfaces. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

We report measurement of Bragg intensities obtained from an Fe3Al(110) single crystal under the condition of total reflection. It is demonstrated that depth-resolved near-surface atomic correlations can be achieved by the independent control of both ocurring grazing angles.

This manuscript presents an experimental effort to directly measure contact areas and the details behind these scaled experiments on a randomly rough model surface used in the “Contact Mechanics Challenge” (2017). For these experiments, the randomly rough surface model was scaled up by a factor of 1000× to give a 100 mm square sample that was 3D printed from opaque polymethylmethacrylate (PMMA). This sample was loaded against various optically smooth and transparent samples of PDMS that were approximately 15 mm thick and had a range in elastic modulus from 14 kPa to 2.1 MPa. During loading, a digital camera recorded contact locations by imaging the scattering of light that occurs off of the PMMA rough surface when it was in contact with the PDMS substrate. This method of illuminating contact areas is called frustrated total internal reflection and is performed by creating a condition of total internal reflection within the unperturbed PDMS samples. Contact or deformation of the surface results in light being diffusely transmitted from the PDMS and detected by the camera. For these experiments, a range of reduced pressure (nominal pressure/elastic modulus) from below 0.001 to over 1.0 was examined, and the resulting relative contact area (real area of contact/apparent area of contact) was found to increase from below 0.1% to over 60% at the highest pressures. The experimental uncertainties associated with experiments are discussed, and the results are compared to the numerical results from the simulation solution to the “Contact Mechanics Challenge.” The simulation results and experimental results of the relative contact areas as a function of reduced pressure are in agreement (within experimental uncertainties).

Chapter 1 - Wave theory of optical waveguides

Propagation and radiation of electromagnetic waves in a lossless, reciprocal, chiral medium is studied in this thesis. Such a medium is described electromagnetically by the constitutive relations D = eE + iγB and H = iγE + (1/µ)B. The constants e, µ, γ are real and have values that are fixed by the size, shape, and the spatial distribution of the elements that collectively compose the medium. The plane wave propagation in an unbounded chiral medium is considered. The propagation constants are obtained and the polarization properties of electromagnetic waves in such a medium are discussed in detail. The problem of reflection from, and transmission through a semi-infinite chiral medium is solved by obtaining the Fresnel equations. The conditions for the total internal reflection of the incident wave from the interface, and the existance of the Brewster angle are obtained. The effects of the chirality on the polarization and intensity of the reflected wave from the chiral half-space are discussed and illustrated by employing the Stokes parameters. The propagation of electromagnetic waves through an infinite slab of chiral medium is formulated for oblique incidence and solved analytically for the case of normal incidence. The radiation emitted by an oscillating dipole in an unbounded, lossless, chiral medium is calculated. From the constitutive relations and from the time-harmonic Maxwell equations ∇ x E = iωB and ∇ x H = J - iωD, it is seen that the wave equation for such a medium is given by ∇ x ∇ x E - ω2µeE - 2ωµγ∇ x E = iωµJ where the source term J is the current density of the oscillating dipole and where E is the electric vector of the radiated field. The desired solution of this wave equation is found by the dyadic Green's function method, that is, by first constructing the dyadic Green's function Γ and then evaluating the expression E = iωµ∫Γ(r,r')•J(r')dV'. The dyadic Green's function Γ and the components of the radiated electric field E are obtained in closed form. The components of the radiated B, D, and H fields can be derived from knowledge of E by using the Maxwell equation B = (1/iω)∇ x E and the constitutive relations. The wave impedance of the medium and the radiation resistance of the dipole are also obtained. The effects of the chiral medium on the polarization and intensity of the dipole radiation are discussed.

To investigate the excitation process of surface plasmon by fast positrons, we measured the positron energy loss spectra from Si(111)-7×7, Al(111)-1×1, and Bi(001)-1×1 surfaces under the total reflection condition using an energy-filtered reflection high-energy positron diffraction. We observed the multiple surface plasmon excitations, which can be represented by the Poisson distribution with the mean excitation number of 2.4-2.8. The energy loss spectrum is nearly independent of the glancing angle of the incident positron beam. We also measured the electron energy loss spectra at similar glancing angles and determined the mean excitation number to be 1.4-1.8. We found that due to the total reflection positrons are able to excite more surface plasmons as compared to electrons. [DOI: 10.1380/ejssnt.2010.190]

Recently, we developed new total reflection high-energy positron diffraction (TRHEPD) apparatus [1] on a beam line of the linac-based intense positron beam of the Slow Positron Facility at KEK, Japan. The high intensity allows us to install a brightness-enhancement section, which to observation of clear positron diffraction patterns for crystal surfaces under total reflection condition. In this work, we investigated the atomic configuration of Pt-induced nanowires formed on a Ge(001) surface [2] using the apparatus. By means of the diffraction intensity analysis based on the dynamical diffraction theory, or TRHEPD rocking curve analysis, a previously proposed theoretical model [D. E. P. Vanpoucke et al., Phys. Rev. B 77, 241308(R) (2008)], composed of Ge dimers on the top layer and buried Pt arrays in the second and fourth layers, was confirmed to be the fundamental structure of the nanowire. We also investigated the atomic configuration of a rutile-TiO2(110) surface. It is well known that the structure of this surface transforms its periodicity from (1×1) to (1×2) by elevating the sample temperature above ~1100 K, whereas the detailed structure is yet to be revealed. There is a longstanding controversy between the structure models proposed by scanning tunneling microscopy, low energy electron diffraction, surface X-ray diffraction, first-principles calculation with density functional theory results, etc. To solve the problem, we have measured TRHEPD rocking curves and determined the atomic arrangements of the topmost crystal surface [3].