Sol–gel based anti-reflection coatings on wedged laser rods using a spin coater

Anti-reflection (AR) sol–gel coatings are deposited on wedge glass optics for high-power lasers using spin coating technique. Characterization of these coatings on BK-7 glass substrates is carried out in terms of thickness profile across the surface, thickness variation w.r.t. wedge angle, and its effect on AR coating reflectivity, at different wedge angles from 1° to 7°. Results of the study are used to deposit AR coatings on inclined end faces of Nd:phosphate glass laser rods.     

Electrical conductivity of Ag/Na ion-exchanged titanosilicate glasses

The Ag₂O–TiO₂–SiO₂ glasses were prepared by Ag⁺/Na⁺ ion-exchange method from Na₂O–TiO₂–SiO₂ glasses at 380–450 °C below their glass transition temperatures (T_g), and their electrical conductivities were investigated as functions of TiO₂ content and the ion-exchange ratio (Ag/(Ag+Na)). In a series of glasses 20R₂O·xTiO₂·(80−x)SiO₂ with x=10, 20, 30 and 40 in mol%, the electrical conductivities at 200 °C of the fully ion-exchanged glasses of R=Ag were in the order of 10⁻⁵ or 10⁻⁴ S cm⁻¹ and were 1 or 2 orders of magnitude higher than those of the initial glasses of R=Na. The glass of x=30 exhibited the highest increase of conductivity from 3.8×10⁻⁷ to 1.3×10⁻⁴ S cm⁻¹ at 200 °C by Ag⁺/Na⁺ ion exchange among them. When the ion-exchange ratio was changed in 20R₂O·30TiO₂·50SiO₂ system, the electrical conductivity at 200 °C exhibited a minimum value of 7.6×10⁻⁸ S cm⁻¹ around Ag/(Ag+Na)=0.3 and increased steeply in the region of Ag/(Ag+Na)=0.5–1.0. When the ion-exchange temperature was changed from 450 to 400 °C, the conductivity of the ion-exchanged glass of x=30 decreased. The infrared spectroscopy measurement revealed that the ion-exchange temperature of 450 °C induced a structural change in the glass of x=30. The T_g of the fully ion-exchanged glass of x=30 was 498 °C. It was suggested that the incorporated silver ions changed the average coordination number of titanium ions to form higher ion-conducting pathway and resulted in high conductivity in the titanosilicate glasses.     

Effects of the temperature features of linear birefringence upon the sensitivity of a bulk glass current sensor

The temperature characteristics of linear birefringence and its effect upon the output of a bulk glass current sensor is theoretically analyzed and simulated. The results show that when temperature field distributes evenly, the linear birefringence induced by the mutual pressure between sensing head and surrounding material of the package is the main factor, the sensitivity of the system could be varied more than 1% during changes of temperature within the range of −40–40 °C. These results might be useful to those studying optical glass current sensing techniques.     

A simple optical method for the measurement of glass wool fiber diameter

An optical method for measuring glass wool fiber diameter has been proposed and discussed from the viewpoint of practical use. The method is based on both light scattering and light reflection on the glass wool. The method can measure the mean fiber diameter, d, in the area illuminated by laser light in realtime. The accuracy of the method, i.e., the dimensional resolution, was found to be about 0·7 μm within the diameter range of d7·0 μm.     

Interferometric method of checking parallelism and prism angles

Examples are given of a quick and convenient method of testing optical components: the parallelism of glass blocks; the 90° angle error and pyramidal error of a porroprism; and the error in the 45° angles of a right angle prism. A He-Ne laser source is used and the component to be tested acts as an interferometer.     

Effects of deposition temperature on the surface roughness and the nonlinear optical susceptibility of sprayed deposited ZnO:Zr thin films

Zirconium doped zinc oxide thin films were deposited by reactive chemical pulverization spray pyrolysis technique on heated glass substrates at 400 °C, 450 °C and 500 °C using zinc and zirconium chlorides as precursors. The effect of zirconium dopant and surface roughness on the nonlinear optical properties was investigated using atomic force microscopy (AFM) and third harmonic generation (THG). The best value of susceptibility χ⁽³⁾ was obtained from the doped films with less roughness. A strong third order nonlinear optical susceptibility χ⁽³⁾ = 20.49 × 10⁻¹² (esu) of the studied films was found for the 5% doped sample at 450 °C.     

Optical properties of amorphous films

We have analyzed the optical properties of a-Ge_30-xSb_xS₇₀ chalcogenide glass films (x=0,10,20 and 30 at%); the chalcogenide films were prepared by vacuum thermal evaporation. The optical-absorption data indicate that the absorption mechanism is non-direct transition. We found that the optical band gap, E_opt, decreases from 2.04±0.01 to 1.74±0.01 eV, whereas the refractive index increases with increasing Sb content. Data are analyzed by the Wemple equation, which is based on the single-oscillator model.     

Zygo interferometer for measuring refractive index of photorefractive bismuth silicon oxide (Bi12SiO20) crystal

An application of the Zygo system for measuring the refractive index of optical materials such as bismuth silicon oxide (BSO) having a higher value of the refractive index than that of glass is presented. The setting accuracy is found to be of the order of 1 μm in the Zygo phase measuring interferometer. The mean value of refractive index of BSO crystal measured by the interferometer for several samples of thickness in the range of 3–9 mm is 2.542 at a wavelength of 632.8 nm. The accuracy of measurement is ±0.002. It is possible to achieve an accuracy of ±0.0003 for a sample of thickness of 30 mm in the measurement of refractive index due to high setting accuracy of the Zygo system.     

A combined analysis of the hadronic and leptonic decays of the Z

We report on a measurement of the mass of the Z⁰ boson, its total width, and its partial decay widths into hadrons and leptons. On the basis of 25 801 hadronic decays and 1999 decays into electrons, muons or taus, selected over eleven energy points between 88.28 GeV and 95.04 GeV, we obtain from a combined fit to hadrons and leptons a mass of M_z=91.154±0.021 (exp)±0.030 (LEP) GeV, and a total width of Γ_z=2.536±0.045 GeV. The errors on M_z have been separated into the experimental error and the uncertainty due to the LEP beam energy. The measured leptonic partial widths are Γ_ee=81.2±2.6 MeV, Γ_μμ=82.6± 5.8 MeV, and Γ_ττ=85.7±7.1 MeV, consistent with lepton universality. From a fit assuming lepton universality we obtain Γ_ℓ⁺ ℓ⁻ = 81.9±2.0 MeV. The hadronic partial width is Γ_had=1838±46 MeV. From the measured total and partial widths a model independent value for the invisible width is calculated to be Γ_inv=453±44 MeV. The errors quoted include both the statistical and the systematic uncertainties.     

Preparation and electrical properties of the 0,37Li2S-0,18P2S5-0,45LiI glass

A new lithium vitreous electrolyte has been found in the LiI---Li₂S---P₂S₅ system. LiI concentration in the glass, 45% moles, is close to the solubility limit of LiI in 2Li₂S---P₂S₅ glass.The activation energy is of the order of 7.2 Kcal.mole⁻¹ and the conductivity value is 10⁻³ (ohm cm)⁻¹ at 25°C. The conduction is ionic and assured by Li⁺ ions.     

N Chemical Shift Tensor Magnitude and Orientation in the Molecular Frame of Uracil Determined via MAS NMR

The potential of heteronuclear MAS NMR spectroscopy for the characterization of ¹⁵N chemical shift (CS) tensors in multiply labeled systems has been illustrated, in one of the first studies of this type, by a measurement of the chemical shift tensor magnitude and orientation in the molecular frame for the two ¹⁵N sites of uracil. Employing polycrystalline samples of ¹⁵N₂ and 2-¹³C,¹⁵N₂-labeled uracil, we have measured, via ¹⁵N–¹³C REDOR and ¹⁵N–¹H dipolar-shift experiments, the polar and azimuthal angles (θ, ψ) of orientation of the ¹⁵N–¹³C and ¹⁵N–¹H dipolar vectors in the ¹⁵N CS tensor frame. The (θ_NC, ψ_NC) angles are determined to be (92 ± 10°, 100 ± 5°) and (132 ± 3°, 88 ± 10°) for the N1 and N3 sites, respectively. Similarly, (θ_NH, ψ_NH) are found to be (15 ± 5°, −80 ± 10°) and (15 ± 5°, 90 ± 10°) for the N1 and N3 sites, respectively. These results obtained based only on MAS NMR measurements have been compared with the data reported in the literature.     

Effect of surface roughness of TiO2 films on short-circuit current density of photoelectrochemical cell of ITO/TiO2/PVC-LiClO4/graphite

This paper reports the effect of surface topography of titanium dioxide films on short-circuit current density of photoelectrochemical solar cell of ITO/TiO₂/PVC-LiCLO₄/graphite. The films were deposited onto ITO-covered glass substrate by screen-printing technique. The films were tempered at 300 °C, 350 °C, 400 °C, 450 °C and 500 °C for 30 min to burn out the organic parts and to achieve the films with porous structure. The surface roughness of the films were studied using scanning electron microscope (SEM). Current–voltage relationship of the devices were characterized in dark at room temperature and under illumination of 100 mW cm⁻² light from tungsten halogen lamp at 50 °C. The device utilising the TiO₂ film annealed at 400 °C produces the highest short-circuit current density and open-circuit voltage as it posses the smoothest surface topography with the electrolyte. The short-circuit current density and open-circuit voltage of the devices increase with the decreasing grain size of the TiO₂ films. The short-circuit current density and open-circuit voltage are 0.6 μA/cm² and 109 mV respectively.     

Intrinsic dosimetry of glass containers used to transport nuclear materials: Potential implications to the fields of waste management and nuclear forensics

Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) dosimetry were used to measure dose effects in borosilicate glass with time, from 10 min to 60 days following exposure to a dose of up to 100 Gy. TL and EPR results were consistent and performed similarly, with both techniques capable of achieving an estimated limit of detection of between 0.5 and 1 Gy. Three peaks were identified in the TL glow curve at roughly 110 °C, 205 °C, and 225 °C. The intensity of the 205 °C peak was the dominant peak over the time period of this study. The stability of all of the peaks with time since irradiation increased with their corresponding temperature and no significant variation was observed in the glow curve response to a specified total dose attained at different dose rates. The intensity of the 205 °C peak decreased logarithmically with time regardless of total dose. Based upon a conservative limit of detection of 3.3 Gy, a 100 Gy dose would still be detected 2.7E3 years after exposure. Here, we introduce the concept of intrinsic dosimetry, the measurement of the total absorbed dose received by the walls of a container containing radioactive material. The foreseen advantage of intrinsic dosimetry comes from considering the measured absorbed dose received by containers in concert with the characteristics (amount, type) of the source of that dose, the radioactive material contained within the walls of the container, in order to provide enhanced information about the history of an unknown sample in question. Three hypothetical scenarios are presented to introduce this method and to illustrate how intrinsic dosimetry might benefit the fields of nuclear forensics and waste management.     

Rotational absorption spectrum of methylene fluoride in the 20–100 cm region

The pure rotational spectrum of CH₂F₂ was recorded in the 20–100 cm⁻¹ spectral range and analyzed to obtain rotation and centrifugal distortion constants. Analysis of the data yielded rotation constants: A = 1.6392173 ± 0.0000015, B = 0.3537342 ± 0.00000033, C = 0.3085387 ± 0.00000027, τ_aaaa = −(7.64 ± 0.46) × 10⁻⁵, τ_bbbb = −(2.076 ± 0.016) × 10⁻⁶, τ_cccc = −(9.29 ± 0.12) × 10⁻⁷, T₁ = (4.89 ± 0.20) × 10⁻⁶, and T₂ = −(1.281 ± 0.016) × 10⁻⁶cm⁻¹.     

The rotational-vibrational spectra of HNCS and DNCS : An analysis of the high resolution spectra

Ro-vibrational spectra of HNCS and DNCS have been obtained in the spectral range 300–4000 cm⁻¹ with a practical resolution limit of 0.06 cm⁻¹ in the region 350–1200 cm⁻¹ and 0.15 cm⁻¹ in the region 1200–4000 cm⁻¹. The observed fine structure permitted definitive assignments for some of the ^PQ_K, ^QQ_K, and ^RQ_K branches in both molecules, and yielded sets of rotational constants in substantial agreement with those obtained from recent microwave and far-infrared studies. Precise estimates of the band origins have been obtained and there is evidence of second-order Coriolis coupling between the three bending modes in each molecule. The isolation of the out-of-plane bending modes has lead to a re-assignment of ν₃, ν₄, ν₅, and ν₆ for each molecule. The band origins, uncorrected for Coriolis interaction, are for HNCS and DNCS, respectively. v₁:3538.6 ±0.3, 2644.5±0.5cm⁻¹;v₂:1989.0 ±0.3, 1944.3±0.5cm⁻¹;v₃:857.0 ±0.6, 851.0±0.1cm⁻¹;v₄:615.0 ±0.5, 549.1±0.2cm⁻¹;v₅:469.2 ±0.1, 365.8 ±0.2cm⁻¹;v₆:539.2 ±0.5, 481.0±0.1cm⁻¹;     

Measurement of the form-factor ratios for

The form factor ratios r_V=V(0)/A₁(0), r₂=A₂(0)/A₁(0) and r₃=A₃(0)/A₁(0) in the decay , have been measured using data from charm hadroproduction experiment E791 at Fermilab. From 3034 (595) signal (background) events in the muon channel, we obtain r_V=1.84±0.11±0.09, r₂=0.75±0.08±0.09 and, as a first measurement of r₃, we find 0.04±0.33±0.29. The values of the form factor ratios r_V and r₂ measured for the muon channel are combined with the values of r_V and r₂ that we have measured in the electron channel. The combined E791 results for the muon and electron channels are r_V=1.87±0.08±0.07 and r₂=0.73±0.06±0.08.     

One- and two-dimensional C–H/N–H dipolar correlation experiments under fast magic-angle spinning for determining the peptide dihedral angle φ

A recently proposed ¹³C–¹H recoupling sequence operative under fast magic-angle spinning (MAS) [K. Takegoshi, T. Terao, Solid State Nucl. Magn. Reson. 13 (1999) 203–212.] is applied to observe ¹³C–¹H and ¹⁵N–¹H dipolar powder patterns in the ¹H–¹⁵N–¹³C–¹H system of a peptide bond. Both patterns are correlated by ¹⁵N-to-¹³C cross polarization to observe one- or two-dimensional (1D or 2D) correlation spectra, which can be simulated by using a simple analytical expression to determine the H–N–C–H dihedral angle. The 1D and 2D experiments were applied to N-acetyl[1,2-¹³C,¹⁵N] -valine, and the peptide φ angle was determined with high precision by the 2D experiment to be ±155.0°±1.2°. The positive one is in good agreement with the X-ray value of 154°±5°. The 1D experiment provided the value of φ=±156.0°±0.8°.     

Inclusive production of the meson in hadronic decays of the Z boson

The inclusive production rate of the ρ^±(770) vector meson in hadronic Z decays is measured with the ALEPH detector at the LEP collider. A total of 3.2 million hadronic events are selected from data recorded between 1991 and 1995. Decays of ρ^±→π⁰+π^± are reconstructed for x_E>0.05 and x_p>0.05 where x_p=p_ρ/p_beam and x_E=E_ρ/E_beam. The average ρ^± multiplicity per hadronic event is evaluated to be N(ρ^±)=2.59±0.03±0.15±0.04 where the first error is statistical and the second systematic. The third error is from the uncertainty in the extrapolation to x_p=x_E=0. The rates and differential cross-section are compared with Monte Carlo model predictions and OPAL measurements. Residual Bose–Einstein correlations are found to be an important component in the analysis.     

Self-assembly of Ag nanopowder on OTS-patterned glass

Ag ink was spontaneously patterned on glass substrate by using the surface energy difference of a pre-patterned octadecyltrichlorosilane (OTS) layer. Ag ink was confined into the hydrophilic area, where OTS layer was not formed. OTS layer was selectively transferred by micro-contact printing (μCP) method and significantly decreased surface energy. As a result, surface of glass substrate was separated as hydrophobic and hydrophilic with and without OTS layer, respectively. Ag line could be successfully patterned with the width of below 10 μm on the glass. The patterned Ag line was dense and abrupt on the edge and the thickness was about 0.25 μm. Ag film showed good adhesion on a glass substrate after anneal above 200 °C. The minimum resistivity was about 4 μΩ cm.     

Investigations on the scattering of α-particles on Li

Excitation functions of α-scattering on ⁷Li leading to the ground and first excited states have been measured in the bombarding energy regions 8.6–12.5 MeV and 17.0–22.5 MeV at c.m. scattering angles of 54.2°, 72.4° and 89.8°. A systematic deviation from smooth behaviour is revealed which, because of its regularity, is attributed to the exchange of a triton cluster between two α-particles.