Search

The optical community frequently relies on optical adhesives to join multi-component optical assemblies. However, options for bonding infrared materials are limited, since most optical adhesives are organic which means poor index matching to high index materials, and the introduction of their own IR absorption bands. Contact bonding is a potential solution, as it provides adhesion through intermolecular forces, capillary forces, and covalent bonds between bonding surfaces. However, to be successful, a reliable non-destructive characterization technique must be designed to evaluate bond quality. Many optical applications require low temperature processing to avoid degradation of any optical coatings. At room temperature, trapped water in the interface is a dominant contributor to the strength of contact bonded assemblies. Therefore, evaluating the interface is a crucial portion of determining bond quality. This report will analyze the potential of acoustic microscopy as a non-destructive technique to probe trapped water in the bonded interface. Several experiments were conducted to ascertain the sensitivity of acoustic microscopy to trapped water: (i) FTIR spectroscopy was used to provide a benchmark, (ii) bulk silicon samples were bonded in ambient atmosphere and aged over several weeks, (iii) and various annealing procedures were also performed to demonstrate water content evolution. A spring model of the bonded interface is used to quantify the amount of water in these studies through interfacial stiffness. Through these experiments, acoustic microscopy is shown to be an effective non-destructive technique to observe changes in interfacial water and may be used alongside other methods to screen high-value optical assemblies.

BACKGROUND: Stage III or IVA endometrial cancer carries a significant risk of systemic and locoregional recurrence. METHODS: In this randomized phase 3 trial, we tested whether 6 months of platinum-based chemotherapy plus radiation therapy (chemoradiotherapy) is associated with longer relapse-free survival (primary end point) than six cycles of combination chemotherapy alone in patients with stage III or IVA endometrial carcinoma. Secondary end points included overall survival, acute and chronic toxic effects, and quality of life. RESULTS: Of the 813 patients enrolled, 736 were eligible and were included in the analysis of relapse-free survival; of those patients, 707 received the randomly assigned intervention (346 received chemoradiotherapy and 361 received chemotherapy only). The median follow-up period was 47 months. At 60 months, the Kaplan–Meier estimate of the percentage of patients alive and relapse-free was 59% (95% confidence interval [CI], 53 to 65) in the chemoradiotherapy group and 58% (95% CI, 53 to 64) in the chemotherapy-only group (hazard ratio, 0.90; 90% CI, 0.74 to 1.10). Chemoradiotherapy was associated with a lower 5-year incidence of vaginal recurrence (2% vs. 7%; hazard ratio, 0.36; 95% CI, 0.16 to 0.82) and pelvic and paraaortic lymph-node recurrence (11% vs. 20%; hazard ratio, 0.43; 95% CI, 0.28 to 0.66) than chemotherapy alone, but distant recurrence was more common in association with chemoradiotherapy (27% vs. 21%; hazard ratio, 1.36; 95% CI, 1.00 to 1.86). Grade 3, 4, or 5 adverse events were reported in 202 patients (58%) in the chemoradiotherapy group and 227 patients (63%) in the chemotherapy-only group. CONCLUSIONS: Chemotherapy plus radiation was not associated with longer relapse-free survival than chemotherapy alone in patients with stage III or IVA endometrial carcinoma. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00942357.)

Plasma Electrolyte Oxidation (PEO) behavior of AZ91 Mg alloy was investigated in the electrolytes with/without potassium fluoride. Growth rate of coating thickness in the electrolyte containing potassium fluoride (Bath B) was much higher than that in the electrolyte without potassium fluoride (Bath A). The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium fluoride and sodium silicate consisted of MgO, MgF2 and Mg2SiO4. Corrosion current density of oxide layer coated from the electrolyte with potassium fluoride was much lower than that of oxide layer coated from the electrolyte without potassium fluoride. From the result of EIS analysis, it was known that inner barrier layer in the oxide layer coated from the electrolyte with potassium fluoride had a good influence of the corrosion resistance of Mg alloy. The corrosion resistance curves of Bath B were similar to the thickness curves, indicating that the thickness of the oxide layer played an important role in corrosion resistance of AZ91 Mg alloy. The oxide layer in the Bath B containing potassium fluoride was found to be a compact barrier-type passive film in presence of fluoride ions. The existence of the dense MgO and MgF2 in the barrier layer had a favorable effect on the corrosion resistance of the AZ91 Mg alloy formed from Bath B by PEO process. [doi:10.2320/matertrans.MER2008345]

Energy-resolved mass spectroscopy was used to investigate differences in ion-bombardment characteristics during conventional reactive magnetron sputtering of TiN films and their deposition using a grid-assisted magnetron system with anode at a high potential (up to 350 V relative to grounded chamber walls). Narrow ion energy distributions with a maximum corresponding to the ion energy close to 100 eV were obtained for the conventional magnetron deposition on a biased substrate ( V b =−100 V) in an 80%Ar+20%N 2 gas mixture at a pressure of 0.5 Pa. On the contrary, the energy distributions of ions bombarding a grounded substrate in the grid-assisted modified magnetron system with the grid potential V g =+100 V were broadened and extended to higher energies (up to 300 eV) under the same conditions. The change in the ion energy distributions is caused by increase in the plasma potential due to the high anode potential (approximately 320 V in this case). Simultaneously, the total ion flux to the substrate decreased 5.4 times compared with the conventional system. A combined effect of the enlarged kinetic energy of ions and their substantially reduced flux resulted in production of high-quality, densified TiN films with a smooth surface.

Quaternary TiZrAlN nanocomposite thin films were synthesized by Closed-Field Unbalanced Magnetron Sputtering (CFUBMS), and their microstructure and mechanical characteristics were examined. The grain refinement of the TiZrAlN nanocomposite thin films was controlled by adjusting the partial pressure. The hardness of the film varied with the partial pressure and the maximum value was obtained approximately 47 GPa. It was also confirmed that there is a critical value of the grain size() to need maximum hardness.

Quaternary ZrCrAlN nanostructured thin films were synthesized by Closed-Field Unbalanced Magnetron Sputtering, and their microstructure and mechanical properties of the ZrCrAlN nanostructured thin films were examined. The grain refinement of the ZrCrAlN nanostructured thin films was controlled by adjusting the N2 partial pressure. The hardness of the film varied with the N2 partial pressure and the maximum value was approximately 45 GPa. It was also confirmed that there is a critical value of the grain size, dc, needed to maximize the hardness.

This paper presents an optical diagnostic examination of dc planar magnetron discharge used for titanium deposition at 30 mTorr in argon bulk gas. The results were obtained by optical absorption (OAS) and emission (OES) spectroscopy for two distances from the target without substrate. The absolute density of titanium in the ground and metastable states at 4 cm from the target ranged, respectively, between 8 × 1010 cm−3 and 1012 cm−3 and between 6 × 1010 cm−3 and 3 × 1011 cm−3, in the range 0.2–1.0 A. OES results were used to prepare an assumed interpretation in terms of differences in loss mechanisms, mainly by either diffusion towards the walls for all particles at 8 cm from the target or collision losses for non-radiative species at 4 cm from the target, except for the titanium ground state. This was confirmed by our results of the argon metastable density measurement at 4 cm which was constant at around 7 × 1010 cm−3 with discharge current.

In this study, a pulsed magnetron sputtering was employed to synthesize TiN films. We deal with pulse parameters such as pulse frequency and duty cycle in argon–nitrogen plasmas. Also, optical emission spectroscopy and energy resolved mass spectrometry as an integrated plasma diagnostics was employed during synthesis of thin films. The major emission lines and time-averaged ion energy distribution functions (IEDFs) corresponding to various titanium and gas discharge species are in situ surveyed in terms of frequency and duty cycles during deposition. The corresponding surface morphology was analyzed by atomic force microscopy (AFM).

The formation and properties of WC–Ni thin films deposited on Si were studied. A cathodic tungsten carbide arc was used at room temperature to prepare the samples. In this paper, the effect of system parameters, such as external magnetic field, etc., were investigated. Without filtering, only condensed tungsten carbide droplets were observed on the substrate, while transparent films with few droplets were produced when a filter was used to reduce the number of macroparticles. Plasma floating potential and substrate current density were determined by voltage-current analyzer. The change of plasma states during cathodic arc discharges of tungsten carbide, under various magnetic fields of straight magnetic solenoid, was analyzed by optical emission spectroscopy (OES). In addition, an intensified camera system with a fiberoptically coupled high-resolution CCD was used for the estimating distribution of plasma density around the axis of the solenoid coil. Deposition rates of about 20 nm/min of WC–Ni film were determined with α-step. Scanning electron microscopy (SEM) was employed to determine the droplet distribution of the film and surface morphology. The surface roughness remained low over the whole coil current range with values between 0.2 μm at 100 A and 0.8 μm at 200 A.

The spatially resolved optical emission spectroscopy of various species of a pulse DC unbalanced magnetron sputtering is studied. Ar–N2 gas mixtures are used. Emission lines corresponding to titanium cathode and gas discharge species are considered. In this study, the two-dimensional (2-D) emission profiles of the lines are measured by an ICCD camera during TiN coatings. It turns out that the 2-D emission profiles of the various lines behave differently. As a result, we obtained the surface roughness value of RMS 2.3 nm at higher pulse frequency and 3.8 nm at lower pulse duty cycle.

Commercial polymers in thin film form were used for modification by atmospheric RF plasma. The influence of the plasma treatments using Ar and Ar+O 2 on surface energy, morphology and chemical structure of the films was investigated. It was revealed that both modifications caused surface activation of the polymer film, but they obeyed different mechanisms enhancing polymer wettability. First, surface graphitization due to argon sputtering caused hydrogen to free the surface and then reacts with oxygen in the air. Second, surface oxidation is connected with the functional group formation. The reactions of Ti with the polymer led to the simultaneous formation of TiCl 2 , TiC, Ti-oxide and they contributed to film adhesion. In comparison with Ar, the mixed Ar+O 2 RF plasma treatment was a more timesaving process and had more influences on surface activation and film adhesion.

This paper presents a modification to conventional magnetron sputtering systems. The introduction of a grid in front of the target increases metal ion ratio in the plasma. By using optical emission spectroscopy (OES) and observing both Ti neutral and Ti ion, the relative ionization could be qualitatively extended to grid-attached magnetron sputtering as compared with conventional magnetron systems. Experiments clearly demonstrate microstructural cross-sectional TEM analysis of the titanium oxide film changes from a columnar-like (anisostropic) structure to a homogenous structure (isotropic), and resulting in a high refractive index. It is believed that more energetic ion bombardment induced the structural changes in films in the case of grid-assisted magnetron sputtering.

The nitriding behavior of the inner surfaces of narrow blind holes with various diameters was investigated by the pulsed DC plasma nitriding process. Optical emission spectroscopy with an optical probe was employed for diagnostic analysis of the plasma during the processes. Active species were analyzed using an optical probe in front of narrow blind holes with diameters of 3–5 mm and a penetration depth of 30 mm. AISI H13 steel was nitrided at 550 °C for 3 h at various pulsed DC duty cycles, nitrogen and hydrogen partial pressures. The hollow-cathode discharge was effectively stabilized by controlling the pulse duty cycle and working pressure. The plasma stability in a narrow hole appeared to be enhanced by increasing working pressure and decreasing pulse duty cycle.

We have investigated nitriding behavior by a pulsed DC plasma nitriding process. For effective control, it is necessary to monitor the density of the active nitrogen species in the plasma, which is responsible for the enhanced plasma–ferro-metal reaction. An optical emission spectroscopy (OES) method was employed for diagnostic analysis of the plasma during the processes. In this study, AISI H13 steels were nitrided at 550 °C for 4 h with various discharge times and nitrogen concentrations. Active species such as N 2 + , N 2 * were evaluated in terms of the first negative system [N 2 + (B 2 Σ u + , ν ′)→N 2 + (X 2 Σ g + , ν″ + hν ], the second positive system [N 2 (C 3 Π u , ν ′)→N 2 (B 3 Π g , ν″ )+ hν ] of nitrogen and Balmer series of hydrogen by OES. In addition, the structures of the samples were analyzed by XRD. It was found that the compound layer consists of the dominant γ′-Fe 4 N phase.

The quality of pentacene films in pentacene-based devices significantly affects their performance. In this report, the effects of various defects in graphene on a pentacene film were studied with scanning tunneling microscopy. The two most common defects found in the epitaxial graphene grown on SiC(0 0 0 1) substrates were subsurface carbon nanotube (CNT) defects and step edges. The most significant perturbation of the pentacene films was induced by step edges between single-layer and bilayer graphene domains, while the effect of step edges between single-layer domains was marginal. The subsurface CNT defects slightly distorted the structure of the single-layer pentacene, but the influence of such defects decreased as the thickness of the pentacene film increased. These results suggest that the uniformity of the graphene layer is the most important parameter in the growth of high-quality pentacene films on graphene.

Summary form only given, as follows. It is well known that thin film growth and surface morphology can be substantially modified by ion-bombardment during the deposition. This is particularly important in case of thin-film deposition at low temperatures where the film growth occurs under highly nonequilibrium conditions. An attractive way to promote crystalline growth and surface morphology is deposition of additional energy into the surface of the growing film by bombardment with hyperthermal particles. We deposited crystalline Ti and TiN thin films on Si substrate by magnetron sputtering method with grid. Its thin films were highly smoothed and dense as increasing grid bias. In order explore the benefits of a bombardment of the growing film with high energetic particles, Ti and TiN films were deposited on Si substrates by an imbalanced magnetron sputter source with attached grid assembly for energetic ion extraction. Also, we have studied the variation of the plasma states for the feedback control of nucleation and growth behavior by Langmuir probe and Optical Emission Spectroscopy (OES). The epitaxial orientation, microstructual, optical characteristics and surface properties of the films were analyzed by XRD, SEM, ellipsometry and AFM.

Summary form only given, as follows. Magnetron sputtering is a broadly used process for coating thin films for display applications, semiconductor applications, hard coatings, decorative coatings, optical coatings, and so on. In order to enhance the film properties and deposition rate various magnetron sputtering sources have been developed such as dual magnetron sputtering, ionized magnetron sputtering, grid assisted magnetron sputtering, and so on. We have developed high efficiency magnetron sputtering sources. In this study, we investigated of spectroscopic study for ionization enhancement in the magnetron sputtering process with a solenoid coil. The sputtering cathode used in the experiment is a unbalanced magnetron sputtering source with a Ti target which is coupled with a solenoid coil. The active species were evaluated in terms of the 1st negative system and 2 nd positive system of nitrogen, Ar I (4p'-4s') and Ar II (4p-4s) by optical emission spectroscopy.

Using the self-consistent charge extended Huckel procedure, the charge density difference Δϱ at Fe57 nucleus, between hemin and Fe+3 ion is calculated. This is combined with the recent value of the calibration constant, −0.23±0.02a 0 3 mm/sec to obtain an isomer shift of −0.374 mm/sec between hemin and Fe+3 in good agreement with the value −0.392 mm/sec derived from experimental data and the calculated value of the isomer shift of Fe+3 with respect to K3FeF6 from first principle covalency investigations in the latter compound. Δϱ is composed of contributions from core and valence electrons of the same order of magnitude, with the latter being more than one-half of the former. The core contribution is composed of a number of terms of comparable magnitude and differing signs, whose significance is discussed.