Sapphire Prism Research Articles

Wax appearance temperature in crude oils measured by surface plasmon resonance

To predict and quantify the wax appearance temperature in crude oils, we proposed and implemented a well-explored sensing method known as surface plasmon resonance. This phenomenon occurs when an incident light beam couples into a metallic surface. As sensing method, this phenomenon has been widely used in biosensing applications. In this research, we showed the effectiveness of the surface plasmon resonance sensing technique in hydrocarbon sensing in general and in crude oil wax appearance prediction in particular. To the authors knowledge, this is the first exploration of monitoring wax deposition events from crude oil using surface plasmon resonance measurements. A compact optical sensor was developed from an ultra-thin layer of gold deposited on a sapphire prism and supported by a new data analyzing metric to analyze the acquired reflected beam intensity profile and detect the precipitation of crude oil wax or other hydrocarbon particles under varying-temperature and low-pressure conditions. The obtained wax appearance temperatures using the introduced on-site method were found to be comparable with the literature measurements using the common in-lab Cross-Polarization Microscopy method.

Visualization analysis of temperature distribution in the cavity of conventional PPS and high-thermal-conductivity PPS during the filling stage of injection molding

Abstract As a highly thermally conductive PPS that is lightweight and has excellent heat dissipation is expected to be applied in various products, its peculiar filling behavior can cause molding defects such as short shots and surface cracks. To address these challenges, it is important to elucidate the filling behavior and clarify the effects of cavity shape and molding conditions. Thus, we intend to visualize the filling behavior of the high-thermal-conductivity PPS. To achieve this goal, we develop an in-process visualization system to reveal both the thermal and kinetic behaviors of the resin while it fills the cavity. In the system, a sapphire prism glass is utilized in the mold for visualization because it exhibits high strength, high heat conduction, and high infrared transmittance. A high-speed visible camera for kinetic behavior and an infrared camera for thermal behavior are utilized. With the developed system, we successfully obtained for the first time the filling behavior of high-thermal-conductivity PPS. Visualization experiments prove that the temperature of the conventional PPS gradually decreases from the tip to the rear of the flow. However, the temperature of the high-thermal-conductivity PPS drops sharply from the tip of the flow to the rear, and breakage at the flow front near the cavity wall is generated. Our interpretation is that the flow front near the cavity wall can be easily broken when it is stretched, because the ductility of the high-thermal-conductivity PPS largely decreases because of the rapid temperature drop. To suppress the formation of this breakage, we modify the cavity shape and molding conditions, and verify its suppression effect.

Autofluorescence Imaging of Living Yeast Cells with Deep-Ultraviolet Surface Plasmon Resonance

Autofluorescence in living cells on aluminum thin film was excited with deep-ultraviolet surface plasmon resonance (deep-UV SPR). Deep-UV SPR under aqueous medium was excited with Kretschmann configuration by using a sapphire prism. Deep-UV SPR is one of the promising techniques for high-sensitive autofluorescence imaging of living cells without staining. Label-free observation is significant for the structural analysis of living cells. We demonstrated the high-sensitive autofluorescence imaging of living yeast cells with deep-UV SPR. We applied a high refractive index prism, such as sapphire, which is suitable for the observation of specimens in aqueous medium, to excite deep-UV SPR. Although typical autofluorescence from living cells is buried in background noise, deep-UV SPR enhances the autofluorescence signal. The deep-UV SPR excitation of an aluminum thin film through a sapphire prism was investigated theoretically and experimentally. It showed that the fluorescence intensities are increased 2.8-fold. Deep-UV SPR enhanced the autofluorescence of cell structures, and yeast cells were found to be very sensitive. As a result, for water-immersed specimens, the sapphire-prism-based Kretschmann configuration excited SPR in deep-UV. Findings from this study suggest that deep-UV SPR can be considered an effective technique for attaining high-sensitivity observation of biological samples.

Infrared surface-plasmon-resonance attenuator for broadly controllable effective radiant temperature

We describe a controllable infrared plasmonic laser attenuator with application to infrared detector characterization. The device promises a broad range of effective radiant temperature and fine temperature control/resolution near ambient. The enabling mechanism is controllably-frustrated surface-plasmon-resonance using a Kretschmann prism coupler. The predicted wide dynamic range depends on optical and geometric tolerances for the coupler. To investigate these, a mid-wave-infrared coupler comprising a conducting Ga-doped ZnO film deposited directly on a right-angle sapphire prism was fabricated, tested, and compared with theory. The attenuation resonance was observed by measuring specular reflection of a p-polarized quantum cascade laser beam at 4.45 μm wavelength as a function of internal incidence angle from the coated prism face. The predicted resonance for comparison was based on ellipsometrically-obtained optical constants and film thickness. Near perfect match between theory and experiment was achieved after adjusting for experimental uncertainties in optical parameters. The results quantify the accuracy and precision with which optical constants and geometrical parameters must be known to achieve the predicted performance.

Local structures and dynamics of interfacial imidazolium-based ionic liquid depending on the electrode potential using electrochemical attenuated total reflectance ultraviolet spectroscopy

Recently, ionic liquids (ILs) have attracted attention as prospective electrolytes for Li-ion batteries, with safe performance. Herein, the dynamics of the IL at the electrochemical interface, which is the key to the electrochemical reaction, was monitored using attenuated total reflectance far- and deep-ultraviolet (ATR-FUV-DUV) spectroscopy. An original measurement system, which combined an ATR-FUV-DUV spectrometer with a Kretschmann type (fully metal-coated prism) electrochemical setup, was assembled. Spectral measurements and assignments were performed for the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM][TFSI])/Pt electrode (∼7 nm) interface. The incident light in the FUV and DUV regions entered a measurement system comprising an [EMIM][TFSI]/Pt electrode/ATR sapphire prism, and the potential-dependent absorption spectra were measured in the 180–450 nm range. This in-situ spectroscopic technique is unique in that the electronic transition spectra of the interfacial IL can be obtained. By switching the applied potentials, temporal spectral changes (i.e. relaxation signals) were tracked at wavelengths of 450 nm and 221 nm, where the direct electronic absorption of the IL was active and inactive, respectively. Comparing these relaxation times, it was revealed that the absorption signal at 221 nm changed more slowly than that at 450 nm. This indicated that the molecular conformations that affected the electronic absorption of the interfacial ILs changed slowly. Considering the surface-normal dipole selection rule for molecules on a metal surface, it is suggested that the slow changes in the molecular conformations can be ascribed to the potential-dependent interfacial orientations of [EMIM]+.

High Sensitive Biosensors Based on the Coupling Between Surface Plasmon Polaritons on Titanium Nitride and a Planar Waveguide Mode.

High sensitivity biosensors based on the coupling of surface plasmon polaritons on titanium nitride (TiN) and a planar waveguide mode were built; they were proved by sensing three different media: air, water and dried egg white; sensors described here could be useful for sensing materials with a refractive index between 1.0 and 1.6; in particular, materials of biological interest with a refractive index in the range 1.3–1.6, like those containing biotin and/or streptavidin. They were built by depositing Nb2O5/SiO2/TiN multilayer structures on the flat surface of D-shaped sapphire prisms by using the dc magnetron sputtering technique. Attenuated total reflection (ATR) experiments in the Kretschmann configuration were accomplished for the air/TiN/Prism and S/Nb2O5/SiO2/TiN/Prism structures, S being the sample or sensing medium. ATR spectra for plasmons at the TiN/air interface showed a broad absorption band for angles of incidence between 36 and 85°, with full width at half maximum (FWHM) of approximately 40°. For the S/Nb2O5/SiO2/TiN/Prism structures, ATR spectra showed a sharp reflectivity peak, within the broad plasmonic absorption band, which was associated with Fano resonances. The angular position and FWHM of the Fano resonances strongly depend on the refractive index of the sensing medium. ATR spectra were fitted by using the transfer-matrix method. Additionally, we found that angular sensitivity and figure of merit increase with increasing the refractive index of the sensing medium.

Impact dynamics and heat transfer characteristics of liquid nitrogen drops on a sapphire prism

Drops close to a hot solid surface can be prevented from making contact by the vapour generation in between them. This so-called Leidenfrost effect occurs at a minimal plate temperature which is referred to as the Leidenfrost temperature. In spray cooling, were one uses impacting drops to cool down the hot solid, this effect is very undesirable: the vapour layer forms an isolating layer and prevents effective heat transfer between the drop and the solid. We study this phenomenon by impacting a single liquid nitrogen drop on a smooth sapphire prism using high-speed frustrated total internal reflection imaging. In these cryogenic conditions, the prism behaves as a perfect thermal conductor, while its transparency enables us to study the contact behaviour during the impact and the spreading phase of the drop. By varying the prism temperature and impact velocity of the drops we obtain a phase diagram of the impact characteristics. Using the Stokes number for the vapour flow, we find good agreement with previous studies for non-cryogenic liquids. The phase diagram is then compared with a second type of experiment in which a stream of drops cools the prism over time. The results of the two different type of measurements agree well, from which we conclude that the cooling power of a drop is strongly related to the wetting behaviour of the impacting drops. Finally, by comparing the wetted area with the contact line length we show that heat transfer in contact and transition boiling is dominated by conduction rather than evaporation.

THz generation from DFG in a noncollinear phase-matched GaP crystal pumped with a compact diode-pumped two-frequency LiYF4:Nd laser

Pumping with a nanosecond two-frequency compact diode-pumped LiYF4:Nd laser emitting at 1047 and 1053 nm, a THz wave has been produced in a GaP crystal, attributed to the difference frequency generation process $$\frac{1}{{{\lambda _3}}} - \frac{1}{{{\lambda _2}}}=\frac{1}{{{\lambda _{{\text{TH}}z}}}}$$ . In a first set-up, the two pumping beams had a tunable angular separation provided by a sapphire prism. The phase matching angle of the noncollinear interaction has been determined to be 0.202° external angle and the refractive index 3.377 at 1.6 THz. The angular acceptance was rather broad, due to the fact that the thickness of the nonlinear crystal was only 3 mm. With a second set-up using a beam displacer constituted by YVO4 plates of different thicknesses, smaller angular separations were explored under other directions of polarizations of the pump beams. Because at the three wavelengths involved in this study the velocity of the nonlinear polarization wave inside GaP is higher than the THz wave phase velocity, a Cerenkov phase matching is possible. The plane-wave calculations show that the THz radiation under this process exits from the output face of the crystal, as it is experimentally observed.

Transient contact behavior of aqueous polymer solution droplets with transparent hot solid

In the metal forming industry, quench hardening is commonly used to strengthen steel products by rapidly cooling hot materials. One of the typical coolants used in the quench hardening process is an aqueous polymer solution. During the hardening process, several phenomena occur simultaneously, namely, coolant boiling, separation of the polymer from the aqueous solution, and formation of a polymer-enriched layer on the solid surface. The hydrodynamics and heat transfer characteristics of the coolant during the cooling process are complex in nature and remain unclear. The main objective of this study is to develop an experimental understanding of the collision and contact behavior of aqueous polymer solution droplets with a hot substrate. This research will serve as a fundamental reference work for the process of quench hardening using spray cooling. To fulfill this objective, a three-directional flash photography technique was developed. A transparent sapphire prism was used to observe the transient contact behavior of droplets with a hot solid, whose temperature was varied from 300 to 600 °C. A solution of 10 wt% polyoxyethylene-polyoxypropylene glycol with an average molecular weight of approximately 20,000 was used as the test liquid. At a substrate temperature of 300 °C, jellylike polymer residue remained on the substrate. At 400 and 500 °C, a wet area appeared temporarily on the solid substrate soon after the droplet collision, but this area eventually disappeared because of the thermal decomposition of the polymer. At 600 °C, no wet area was seen. The lifetime of the temporary wet area decreased with an increase in the temperature of the solid but was almost independent of the impact inertia of droplets. In addition, in the case of the polymer solution droplet, the upper limit of the surface temperature for forming the wet area was around 580 °C, which was considerably higher than that in the case of a water droplet.

Far- and deep-ultraviolet surface plasmon resonance sensors working in aqueous solutions using aluminum thin films

Surface plasmon resonance (SPR) sensors detect refractive index changes on metal thin films and are frequently used in aqueous solutions as bio- and chemical-sensors. Recently, we proposed new SPR sensors using aluminum (Al) thin films that work in the far- and deep-ultraviolet (FUV-DUV, 120–300 nm) regions and investigated SPR properties by an attenuated total reflectance (ATR) based spectrometer. The FUV-DUV-SPR sensors are expected to have three advantages compared to visible-SPR sensors: higher sensitivity, material selectivity, and surface specificity. However, in this study, it was revealed that the Al thin film on a quartz prism cannot be used as the FUV-DUV-SPR sensor in water solutions. This is because its SPR wavelength shifts to the visible region owing to the presence of water. On the other hand, the SPR wavelength of the Al thin film on the sapphire prism remained in the DUV region even in water. In addition, the SPR wavelength shifted to longer wavelengths with increasing refractive index on the Al thin film. These results mean that the Al thin film on the sapphire prism can be used as the FUV-DUV-SPR sensor in solutions, which may lead to the development of novel and sophisticated SPR sensors.

Cherenkov-type terahertz emission from ultrafast magnetization in a slab of magnetooptic material

We develop a theory of terahertz emission from a slab of a magnetooptic material traversed by a circularly polarized femtosecond laser pulse. The Cherenkov-type radiation is generated by a moving region of ultrafast magnetization optically induced in the slab via the inverse Faraday effect. A prism is used to couple the radiation from the slab to free space. Our theory accounts for transient effects at the slab boundaries and shows their significance for the interpretation of the terahertz waveform emitted from the slab. The theory predicts detectability of the radiation generated by a mJ-level laser pulse in a terbium gallium garnet slab covered with a sapphire prism.

English

We report the determination of refractive indices of polymer dispersed liquid crystal composite within visible spectral range 404-706nm for various temperatures. The droplet domain formation effect in polymer liquid crystal composite system with variation of different polymer dispersed in liquid crystal and pure liquid crystal has been studied. The optical parameters due to scattering by sapphire prism have been measured for pure liquid crystal and polymer dispersed liquid crystal. It is found that the optical anisotropy of polymer dispersed liquid crystal composite system is greatly changed by polar order present in the polymer droplet environment. The scattering is due to both reorientation and thermal effects. The wavelength and temperature dependent refractive indices are fundamentally interesting and practically important for optimizing display performances and other photonic devices employing LCs such as high temperature gradient LCs, high thermal tunable LCs, and photonic liquid crystal fibers

Scanning interference evanescent wave lithography for sub-22-nm generations

Large field, ultra-high numerical aperture (NA) lithography is desired in semiconductor manufacturing. We report progress in developing a scanning evanescent wave lithography (s -EWL) imaging head with a two-stage gap control system including a DC noise canceling air bearing, which houses an AC noise-canceling piezoelectric actuator. Various design aspects of the system, including gap detection, prism design, optical alignment, software integration, feedback actuation, and a scanning scheme have been developed to ensure sub-100-nm gap control. Experimental results have shown successful gap gauging with a gap noise root-mean-square (RMS) of 1.38 nm in static gap control, and 4.64 nm in linear scanning gap control. Integrating the prototype imaging head into a two-beam interferometer platform has demonstrated dynamic stepping imaging using fused silica and sapphire prisms, with potential NA values up to 1.85 (26-nm half-pitch). These results achieved with s -EWL provide a possible route to extend optical lithography to 16-nm generations and beyond when combined with double patterning techniques.

Scanning angle Raman spectroscopy measurements of thin polymer films for thickness and composition analyses

Scanning angle (SA) Raman spectroscopy was used to measure the thickness and composition of polystyrene films. A sapphire prism was optically coupled to a sapphire substrate on which 6–12% (w/v) polystyrene in toluene was spin coated. Raman spectra were collected as the incident angle of the p-polarized, 785-nm excitation laser was varied from 56 to 70°. These angles span above and below the critical angle for a sapphire/polystyrene interface. The thickness of the polystyrene film was determined using a calibration curve constructed by calculating the integrated optical energy density distribution as a function of incident angle, distance from the prism interface and polymer thickness. The calculations were used to determine the incident angle where waveguide modes are excited within the polymer film, which is the angle with the highest integrated optical energy density. The film thicknesses measured by SA Raman spectroscopy ranged from less than 400nm to 1.8μm. The average percent uncertainty in the SA Raman determinations for all films was 4%, and the measurements agreed with those obtained from optical interferometery within the experimental uncertainty for all but two films. For the 1270-nm and 580-nm polystyrene films, the SA Raman measurements overestimated the film thickness by 5 and 18%, respectively. The dependence of the calibration curve on excitation polarization and composition of the polymer and bulk layers was evaluated. This preliminary investigation demonstrates that scanning angle Raman spectroscopy is a versatile method applicable whenever the chemical composition and thickness of interfacial polymer layers needs to be measured.

Plasmon Waveguide Resonance Raman Spectroscopy

Raman spectra were collected from a 1.25 M aqueous pyridine solution, 100-nm polystyrene film or a trimethyl(phenyl)silane monolayer at a plasmon waveguide interface under total internal reflection (TIR). The plasmon waveguide resonance (PWR) interface consisted of a sapphire prism/49 to 50 nm Au/548 to 630 nm SiO(2) and a monolayer, thin film or aqueous analyte. The Raman peak area as a function of incident angle was measured using a 785-nm excitation wavelength, and was compared to the Raman peak area obtained at a sapphire or sapphire/50 nm Au interface. In contrast to measurements at a bare sapphire prism, increased surface sensitivity and signal were obtained from the PWR interface. In contrast to measurements at a bare Au film where only p-polarized incident light generates an enhanced interfacial electric field, plasmon waveguide interfaces enable excitation with orthogonal polarizations using s- or p-polarized incident light. The Raman scatter from a monolayer was recorded at the PWR interface with a signal-to-noise ratio of 5.6 when averaging 3 accumulations with 3 min acquisition times using nonresonant excitation, whereas no signal was recorded from a monolayer at the sapphire interface. The reflected light from the interface enabled the identification of the incident angle where the maximum Raman scatter was produced, and the Raman signal generated at the plasmon waveguide interface was modeled by the enhanced interfacial mean square electric field relative to the incident field. In comparison to the techniques on which this work was based (i.e., PWR spectroscopy, TIR Raman spectroscopy at the prism interface, and surface plasmon resonance (SPR) Raman spectroscopy at the prism/Au interface), chemical specificity was added to PWR spectroscopy, a signal enhancement mechanism was introduced for TIR Raman spectroscopy, and polarization control of the interfacial electric field was added to SPR Raman spectroscopy.

High-Pressure Adsorption of Ethylene on Cubic Pt Nanoparticles and Pt(100) Single Crystals Probed by in Situ Sum Frequency Generation Vibrational Spectroscopy

A model catalytic system of a monolayer consisting of 9-nm average size, cubic, single-crystal Pt nanoparticles and poly(vinylpyrrolidone) (PVP) polymer capping agent deposited on a sapphire prism was investigated by sum-frequency generation (SFG) vibrational spectroscopy in total internal reflection (TIR) geometry. Exposure of a clean nanoparticle monolayer after removal of PVP by cyclic oxidation–reduction treatment to high-pressure ethylene at room temperature led to the formation of ethylidyne and di-σ bonded ethylene. Low-pressure ethylene adsorption on a pseudohexagonal reconstructed Pt(100) single crystal resulted only in the formation of di-σ bonded ethylene. High-pressure adsorption of ethylene on Pt nanoparticle monolayers and Pt(100) led to the formation of both ethylidyne and di-σ bonded ethylene and stabilized the pseudohexagonal reconstruction of Pt(100) on both the single crystal and the surface of clean cubic nanoparticles. Restructuring of the PVP layer caused by CO adsorption indicated a...

Interference Effect from Buried Interfaces Investigated by Angular-Dependent Infrared−Visible Sum Frequency Generation Technique

Infrared-visible sum frequency generation spectroscopy (SFG) in conjunction with total internal reflection geometry (TIR) has been demonstrated as a powerful technique to study buried polymer interfaces. We have developed a theoretical model using linear and nonlinear boundary conditions to calculate the SFG signals as a function of incident angles and thickness of the polymer films. The validity of this model is tested using a polystyrene film (PS) coated on a sapphire prism. This PS film is exposed to heneicosane (C21H44) above and below its melting temperature. At temperatures greater than Tm, the SFG contributions from both interfaces (PS/sapphire and alkane/PS) are comparable and we observe strong interference effects. At temperatures below Tm, the SFG signals are dominated by the methyl signals of all-trans heneicosane molecules at the alkane/PS interface. The theoretical model is able to accurately capture the angle and thickness dependence of the SFG signal and provides a valuable tool to accurate...

3–5 μm AgGaS2 optical parametric oscillator with prism cavity

Employing a coated right-angled sapphire prism as the OPO cavity mirror, AgGaS2 type-I singly resonant optical parametric oscillator was demonstrated experimentally, which was pumped by a ns 1.064 μm Nd:YAG laser. Continuously tunable 2.35 to 5.27 μm radiation without changing cavity mirrors and maximum output energy 0.58 mJ per pulse are recorded.

Sum-Frequency Spectroscopy of a Monolayer of Zinc Arachidate at the Solid−Solid Interface

Infrared-visible sum-frequency spectroscopy has been used to record the vibrational spectrum of a zinc arachidate monolayer at the interface between a sapphire prism and a fused silica lens. Spectra have been recorded for the monolayer deposited on the prism before, during, and after contact, and as a function of increasing pressure. Sum-frequency spectra are reported of the monolayer under sliding contact. The monolayer is found to be resistant to pressure- and shear-induced conformational disorder. However, frequency shifts, drops in peak intensities, and changes in peak intensity ratios have been observed as the monolayer is placed in contact between the prism and the lens. Transfer of monolayer material between the two surfaces is observed and is confirmed by spectra obtained with a monolayer deposited on the surface of the lens rather than the prism. On one face of the sapphire prism, the monolayer reconstructs to a low symmetry layer, probably due to epitaxy. The epitaxial structure disappeared in contact. Existing models for calculating sum-frequency spectra have been extended to include unit cells containing two molecules and torsion about the terminal C-C bond. This model can explain some, but not all, of the experimental observations.

22-nm immersion interference lithography

Immersion interference lithography was used to pattern gratings with 22-nm half pitch. This ultrahigh resolution was made possible by using 157-nm light, a sapphire coupling prism with index 2.09, and a 30-nm-thick immersion fluid with index 1.82. The thickness was controlled precisely by spin-casting the fluid rather than through mechanical means. The photoresist was a diluted version of a 193-nm material, which had a 157-nm index of 1.74. An analysis of the trade-off between fluid index, absorption coefficient, gap size and throughput indicated that, among the currently available materials, employing a high-index but absorbing fluid is preferable to using a highly transparent but low-index immersion media.