Copper Mirrors Research Articles

Recent progress of the compact AFEL at Los Alamos

The Advanced Free Electron Laser (AFEL) is a compact, infrared, rf-linac FEL that uses a high-brightness photoinjector and a short-period permanent-magnet wiggler. Lasing at saturation with and without sidebands was achieved over the 4–6 μm region with a nominally 15-MeV electron beam energy and a 1-cm-period, 24-period wiggler. Sideband-free FEL operation was optimized with respect to outcoupling by tuning off the reflectivity curve of the multilayer dielectric mirrors. Sideband operation was achieved using copper mirrors with a 1.1% outcoupling hole. The measured macropulse energy with ∼ 1300 micropulses was approximately 50 mJ per 1 nC of beam, corresponding to an output efficiency of 0.25% and a maximum extraction efficiency of 1.4%.

Lead‐free Solder Pastes Evaluation at Motorola Transmission Products Division

The increased interest in the electronics industry to search for alternatives to lead‐containing solders is evidenced by the number of recently published articles on lead‐free solders in this journal and other journals. At the latest Surface Mount International conference, several papers were presented on lead‐free solder alloys, conductive adhesives and organic preservatives, all in search of replacements for lead‐containing finishes. The efforts to find a replacement for tin/lead are in response to possible legislation banning lead or possible taxation on the use of lead. In an attempt to reduce the use of lead in this company's assembly operation, five lead‐free solder pastes and four corresponding flux vehicles (for A, B, C and E pastes) were evaluated. All of the flux vehicles passed the standard industry tests except for two flux vehicles (pastes B and C) that failed the copper mirror test. An assembly trial of the lead‐free pastes was carried out by building liquid crystal display panels with minimal process modification. Printability, process compatibility and solder joint reliability were assessed. This paper describes the preliminary results of the authors' investigation.

Cooled bimorph adaptive mirrors for laser optics

Cooled bimorph adaptive copper and molybdenum mirrors are proposed for the compensation of large-scale optical aberrations in laser systems with an output power up to 15 kW. An investigation is reported of the characteristics of the developed and fabricated cooled bimorph mirrors. The experimental results are compared with those obtained by computer modelling. Promising designs of bimorph adaptive mirrors are proposed and discussed.

Copper-catalyzed conjugate additions of organozirconocenes. Synthetic and mechanistic studies.

In the presence of 3–10 mol % of Cu(l) salts such as CuBr·S Me2 or CuCN, alkylzirconocenes add readily to α,β-unsaturated ketones, aldehydes, and sulfones. The reaction yield is sensitive to the presence of Lewis acids and bases. Steric hindrance as well as a broad range of functional groups are tolerated in the conjugate addition process. Unsaturated N-acyl oxazolidinones give high diastereoselectivities for the formation of the new asymmetric carbon. The resulting zirconium enolates can be used for tandem aldol addition reactions to aldehydes. Depending on the type of copper salt used, slow or fast formation of copper mirror occurs, but no intermediate copper species is detected spectroscopically. Therefore, a mechanism involving enone complexation by the Lewis-acidic zirconocene followed by inner-sphere transfer of the alkyl substituent to chelated Cu(l) is proposed.

Role of optical field in photoemission from copper

Photoemission from a diamond turned copper mirror with laser beams of intensity 10 11 W/cm 2 at the photon energy of 2 eV and pulse duration of ∼300 fs indicates that the electric field associated with the photons enhances the photoemission. At the optimum incident angle, the electron yield with p-polarized light was 75 times larger than that with s-polarized light and four times larger than that at normal incidence for a constant energy. These enhancements were underestimated by the changes in the absorption and were attributed in this paper to the optical field effect.

Focusing a beam of ultracold spin-polarized hydrogen atoms with a helium-film-coated quasiparabolic mirror.

We formed the first ``atomic-optics'' beam of electron-spin-polarized hydrogen atoms using a quasiparabolic polished copper mirror coated with a hydrogen-atom-reflecting film of superfluid $^{4}\mathrm{He}$. The mirror was located in the gradient of an 8-T solenoidal magnetic field and mounted on an ultracold cell at 350 mK. After the focusing by the mirror surface, the beam was again focused with a sextupole magnet. The mirror, which was especially designed for operation in the magnetic field gradient of our solenoid, increased the focused beam intensity by a factor of about 7.5.

Optical field enhanced multiphoton photoemission in copper mirrors

Photoemission from diamond turned copper mirror with laser beams of intensity 1011 W/cm2 at the photon energy of 2 eV and pulse duration of ∼300 fs indicates that the electric field associated with the photons enhances the photoemission. At the optimum incident angle, the electron yield with p-polarized light was 75 times larger than that with s-polarized light and 4 times larger than that at normal incidence for a constant energy. These enhancements were underestimated by the changes in the absorption and were attributed in this letter to the optical field effect.

Concentrations, distributions and seasonal variability of dissolved Cd, Co, Cu, Mn, Ni, Pb and Zn in the English Channel

Open ocean studies have shown that dissolved manganese, cobalt and lead exhibit vertical profiles that reflect external sources and short residence times due to scavenging on to particle surfaces. In contrast, dissolved cadmium, copper, nickel and zinc mirror, to different degrees, the profiles of the nutrients. The work reported here for three cruises (November–December 1985, May and July–August 1986) in a shallow shelf sea shows that seasonal variations are shown by metals of the scavenged group, whereas the metals whose cycling in the open ocean parallels those of the nutients, do not show these correlations and, in fact, show no measurable seasonal variability. Concentrations of manganese increased progressively from winter to summer [2.3 ± 0.7(mean± 1σ)to 5.0 ± 3.0 nmol l −1]. A surface enrichment in the upper mixed layer of the western Channel during summer was also observed. Concentrations of cobalt increased from winter to spring (from ≤0.02–0.50 to 0.08–0.71 nmol l −1), paralleling those of manganese, but then decreased into summer (to ≤0.08–0.56 nmol l −1). The regional distribution of lead changed during the spring, possibly reflecting removal by diatoms and decreased river inputs, although overall mean concentrations remained similar throughout the year (0.22 nmol l −1). Concentrations of cadmium (0.20 nmol l −1), copper (3.2 nmol l −1), nickel (3.8 nmol l −1) and zinc (7.6 nmol l −1), and their regional distributions, remained relatively uniform over the period of the observations.

Extraction of infrared radiation from SPring-8

Extraction of infrared beams from SPring-8 storage ring is investigated. SPring-8 is a third generation insertion device oriented synchrotron radiation source in x-ray region. It is noticeable, however, that a highly powerful radiation source in infrared region can be obtained from the bending magnet because of the large bending radius of 40 m. In this wavelength region, SPring-8 storage ring has a very sharp natural collimation in the vertical direction and the source size is very small. Extraction of infrared radiation in wavelength of 2–25 μm was designed. Source is a bending magnet and a water-cooled copper mirror is incorporated into the crotch laid just downstream by the bending magnet. The design of crotch and the transport system is carried out.

Localization of incident laser beam in the optical element by on-site photoacoustic detection

Weak photoacoustic signals generated spontaneously by a laser pulse proved usable for precise detection of the laser beam location on an optical element. Using a couple of acoustic emission sensors attached to the rear surface of a copper mirror, the displacement of a pulsed CO2 laser beam was measured with a precision of less than 0.1 mm. Characteristic features of such photoacoustic signals are also reported.

Some applications of cryosubstitution in ultrastructural studies of the cell nucleus

Cryofixation followed by cryosubstitution, without the use of any chemical fixatives, was carried out on cultured mouse P815 cells. The principal aim of our work, which was to show that these techniques provide excellent morphological preservation of cellular and in particular nuclear components, was demonstrated. All nuclear structural components, nucleolar or nucleoplasmic, were clearly revealed using this technology. The cells were cryofixed by impact freezing onto a copper mirror cooled with liquid nitrogen or helium, cryosubstituted in acetone and embedded in either Lowicryl K11M or 1R White acrylic resin. Ultrathin sections were contrasted using either the usual uranyl acetate-lead citrate double staining, a differential staining for nuclear nucleoprotein structures, or the silver staining revealing nucleolar organizer regions. In view of the absence of conventional fixatives, the specimens prepared in this way would offer to be material of choice for ultrastructural identification of intra-nuclear antigens, especially those sensitive to conventional fixatives such as, for example, aldehydes. Advantages and differences of these techniques with regard to more conventional electron microscopic procedures are discussed.

Endocytosis in elongating root cells of Lobelia erinus

Endocytosis was demonstrated in elongating cortical and epidermal root cells of Lobelia erinus using the apoplast marker lanthanum nitrate. Lanthanum treatment produced electron-dense deposits throughout the cell wall, as well as in coated and smooth vesicles, partially coated reticula, and multivesicular bodies. This labelling pattern was observed in root cells that had been ultrarapidly frozen on a copper mirror and freeze-substituted (cryofixation) or fixed by conventional transmission electron microscope (TEM) techniques. The amount of endocytosis occurring was measured by counting the number of vesicles μm −2 in root cells at various stages of development. Endocytosis occurred most in actively elongating cells, and least in mature cells, which were no longer elongating. The relationship between endocytosis and active cell wall secretion suggests that endocytosis may be acting to remove excess plasma membrane material added during exocytosis of secretory vesicles.

Endocytosis in elongating root cells of Lobelia Erinus

ABSTRACT Endocytosis was demonstrated in elongating cortical and epidermal root cells of Lobelia erinus using the apoplast marker lanthanum nitrate. Lanthanum treatment produced electron-dense deposits throughout the cell wall, as well as in coated and smooth vesicles, partially coated reticula, and multi-vesicular bodies. This labelling pattern was observed in root cells that had been ultrarapidly frozen on a copper mirror and freeze-substituted (cryofixation) or fixed by conventional transmission electron microscope (TEM) techniques. The amount of endocytosis occurring was measured by counting the number of vesicles μm -2 in root cells at various stages of development. Endocytosis occurred most in actively elongating cells, and least in mature cells, which were no longer elongating. The relationship between endocytosis and active cell wall secretion suggests that endocytosis may be acting to remove excess plasma membrane material added during exocytosis of secretory vesicles.

Mechanical properties of coated copper mirrors

Copper mirrors are generally used in optical systems for handling CO 2 laser beams. The presence of a protective coating on the mirror surface is necessary to increase the lifetime of mirrors working in a hostile environment. The mechanical properties (adhesion, hardness and abrasion) of Y 2O 3 and a-C:H protective thin films on copper mirrors have been investigated. Y 2O 3 and a-C:H coatings have been deposited by rf sputtering and dual ion beam sputtering, respectively. The coating adhesion has been measured by the ‘scratch test’ and the ‘topple test’, while the hardness has been measured with the knoop microindentation technique. In order to estimate the abrasion resistance of the samples, the ‘eraser test’ has been performed with a custom-made instrument.

Surface Profiles Obtained by Means of Optical Methods — Are They True Representations of the Real Surface?

Summary The surface profile of the Well known surface of a PTB roughness standard has been recorded by several methods and the results have been compared. The result of the contact stylus method, in particular that using a very small tip radius, is in good conformity with that deduced from SEM stereo images. The optical methods, i.e. laser focus system and interference microscope with image processing, result significant deviations. On the other hand, when the surface of a diamond turned copper mirror is measured, there is a difference of only a few nanometers between the contact stylus method and the interference microscope. Additional investigations will be necessary to find out potential fields of application of the optical methods and to determine the limits set to their application.

New machining method for making precise and very smooth mirror surfaces made from Cu and Al alloys for synchrotron radiation optics

A combined machining method of diamond turning and numerically controlled elastic emission machining has been developed for finishing metal mirror surfaces made from Cu and Al alloys. A mirror surface can be polished without any stress by this method. Shape and roughness of the mirror surface examined in different machining methods are compared and discussed. A precisely shaped mirror with a roughness less than 2-nm Rmax was obtained. A copper mirror was installed in a VUV beamline of the Photon Factory. It is confirmed that the metal mirror finished by the present method has good optical characteristics for synchrotron radiation beamlines.

Soft x-ray analysis system for reflection, secondary electron, and fluorescence spectroscopy

This article describes an UHV compatable soft x-ray analysis system for reflection, secondary electron, and fluorescence spectroscopy. It is equipped with a reflectometer with an angular accuracy of 0.01°. This is achieved with rotary encoders directly coupled to the rotation axes. At the same time, the system is equipped with an electron multiplier, a cylindrical mirror analyzer, and a Si(Li) detector, each for measuring total secondary electrons, photo- and Auger electrons, and fluorescence. Furthermore, it is possible to form multilayer films and analyze them in situ. The performance of the reflectometer has been tested on the beamline BL-8A at the Photon Factory. We present the results of reflectivity measurements for diamond-cut copper mirrors and Langmuir–Blodgett films.

Corrosivity of smoke towards metals

AbstractMany people believe that smoke is corrosive only if it contains acid gases. This leads to associating corrosive potential of smoke from materials directly with the amount of acid gases emitted from them during combustion. In extreme cases, chemical composition (i.e. halogen content) is used as a substitute measure of corrosiveness and, therefore, of material suitability for certain applications. The reality is, however, that everything is usually heavily corroded in a fire, whatever the combustible materials involved. In the present project sets of 5 flat carbon steel coupons and 2 copper mirrors were exposed to smoke from several materials for 1 h, in a chamber at room temperature and at 100°C, and kept for 28 days at 75% relative humidity. Various surface treatments were also studied.The combustibles tested were: a PVC wire compound (PVC WR), a low acid PVC wire compound (PVC LH), a halogen free polyethylene wire compound (PE), wool, wood (Douglas fir, DFIR), polystyrene (PS), neoprene (NPR), nylon (NYL), and a blank (no sample). In order to determine corrosivity the resistance of the copper mirrors and the loss of metal from them was measured. All copper mirrors lost their electrical properties: an almost infinite resistance was measured post‐exposure. The amount of copper lost was very similar for all smokes, but, in the 100°C experiments, the smoke corrosivity ranking was: All steel coupons were corroded too, at least to some extent. The amount of iron lost depended on treatment as well as on the smoke used. In particular, the highest degree of corrosion was found with coupons exposed at very high temperature, where, again, the most corrosive smoke came from nylon. Common wisdom suggests that acid gases result in corrosion of metal. The present work substantiates this fact. However, the acid gas concentration in the atmosphere does not normally correlate with the level of metal corrosion. The results of this work indicate that metal corrosion depends on factors in addition to acid gases: type of metal, temperature, humidity, length of exposure, surface treatment, and geometry. Furthermore all smokes tested are corrosive.

Corrosive effects of smoke on metal surfaces

Corrosion of metal surfaces is usually associated purely with acid gases. It is well known, however, that all structural elements (even noncombustible ones) present in a fire are heavily corroded by it, whatever the materials involved in the fire. This project investigated corrosion from burning materials releasing acid, alkaline and neutral smoke, even without thermal damage. Carbon steel coupons, with various pre- and post-treatments, and copper mirrors, were exposed to 30 g/m 3 of smoke in a static chamber at high humidity for 1 h, close to ambient temperature and at c. 100°C. Metal samples were held 28 days before analysis. The materials used for generating smoke were: a generic PVC wire and cable compound, a low HCl emission PVC wire and cable compound, a halogen-free polyethylene wire and cable compound, wool, wood, polystyrene, neoprene, nylon and none (control). All copper mirrors exhibited almost infinite resistance after exposure. Nitrogen-containing materials caused the severest copper corrosion, by dissolving more copper than the other smokes. All steel coupons were corroded. The amount of weight loss dependent on treatment and type of smoke. Corrosion was minimised by cleaning the combustion debris soon after exposure. The corrosion of untreated steel coupons exposed at different temperatures showed that the extent of condensation plays a crucial role. Acid gas concentration correlated with corrosion only if condensation onto the target was artificially enhanced, by placing the target at a lower temperature than the surrounding surfaces. This work has shown: 1. (a) Smoke is corrosive, even in the absence of acid gases. 2. (b) Target treatment, before and after exposure, critically affects the level of corrosion. 3. (c) Smoke corrosivity testing should involve corrosion of actual targets.

Light-induced losses and dark recovery rates of guanosine 3',5'-cyclic monophosphate in rod outer segments of intact amphibian photoreceptors.

We used an apparatus in which pieces of dark-adapted amphibian retinas (Rana pipiens, Bufo marinus) obtained under infrared illumination were exposed to precise intervals of 500-nm illuminations, and then frozen by contact of their outer segment surface with a liquid helium-cooled copper mirror. Sections of the frozen outer segment layer were obtained in a cryostat and then assayed for total extractable cyclic 3',5'-guanosine monophosphate (cGMP). Significant losses of cGMP with respect to the dark level were evident as early as 60 ms after light onset. With dim subsecond illuminations these losses were surprisingly large, which suggests a previously underestimated magnification in the cGMP cascade, or a transient substantial inhibition of guanylate cyclase activity in combination with increased cyclic GMP phosphodiesterase activity. Within the subsecond period, significant losses that were proportional to light intensity (2-log-unit range) and duration (60-550 ms) were generally not evident. However, losses significantly proportional to these factors became evident with durations of 1 s or longer. When pieces of retina were first illuminated (10 or 60 ms), then held in darkness for increasing periods before freezing, we observed a continuous loss of cGMP during the early postillumination dark period, followed by a recovery of the total cGMP level. The times for recovery to the preillumination level appear to be significantly longer than times reported for the recovery of the photoreceptor membrane potential after similar light exposures.