Rhodium mirror

Photographs of the moon obtained with a 30 cm telescope mirror coated with rhodium (a) and with silver (b). The photos were made in Berlin in 1938 [91]. As can be seen by observation of the craters a sharper and halo-free picture was obtained with the rhodium mirror as a consequence of the finer grained and smoother coating. 

Typical reflectance curves for the NIST standard mirrors are shown in (Fig. 1). First-surface silver mirrors are becoming increasingly rare because they are typically prone to oxidation. Rhodium mirrors, although highly... 

The bluish white, hard, yet ductile, metal is inert to all acids and highly non-abrasive. Used for heavy-duty parts in electrical contacts and spinning jets. Reflectors are prepared from the mirror-smooth surfaces (e.g. head mirrors in medicine). Thin coatings provide a corrosion-resistant protective layer, for example, for jewelry, watches, and spectacle frames. The metal is a constituent of three-way catalysts. Rhodium complexes are used with great success in carbonylations (reactions with CO) and oxidations (nitric acid) in industry. Platinum-rhodium alloys are suitable thermocouples. 

Finally, alternatives exist to the use of silver in various materials and processes. These include substitution of aluminum and rhodium for silver in mirrors and other reflecting surfaces tantalum replacement of silver in surgical plates, pins, and sutures stainless steel as an alternative material to silver in the manufacture of table flatware and, in photography, film with reduced silver content (Reese 1991). 

Uses. Electroplating manufacture of rhodium-platinum alloys manufacture of high-reflectivity mirrors... 

Pickering and Eckstrom evaporate catalyst metals, such as rhodium or nickel, onto the mirrors of a White multiple (20-40) reflection cell (68). A series of scans are taken before and after adsorption of the gases. The comparison of the two sets of curves is accomplished by a method described by King et al. (69), in which the detector output is fed to an ana-log-to-digital converter for recording on punched cards. The final graphs are plotted with an IBM accounting machine. This technique makes it possible to study absorption bands of the order of 0.03 to 0.05% of the radiation. 

Figure 9.3 Catalytic cycles for the asymmetric hydrogenation of a-acetamido methyl acrylate (or cinamate). For clarity the detailed structure of the organic substrate is not shown. In 9.21 and 9.22 for ease of identification the carbon atom to which the metal hydride is transferred is marked by an arrow and the hydride is circled. Note that, excepting the chelating chiral phosphine, the stereochemistries around the rhodium in the left- and right-hand cycles have mirror-image relationships.

Platinum and palladium are useful in catalysis. Many of the elements are resistant to corrosion platinum is employed for electrodes and crucibles and extensively for spinnerets to extrude rayon, and rhodium provides a surfacing material for searchlight mirrors. Palladium is used for purifying hydrogen which diffuses rapidly and selectively through the warm metal. 

Most rhodium alloys are used for industrial or research purposes, such as laboratory equipment and thermocouples. A thermocouple is a device for measuring very high temperatures. Rhodium alloys are also used to coat mirrors and in searchlights because they reflect light very well. Rhodium is sometimes alloyed with other precious metals in the manufacture of jewelry and art objects. 

Rhodium is used as an alloy with platinum, and as a catalyst. It is also used as a corrosion-resistant electroplate for protecting silverware from tarnishing, for making high-reflectivity mirrors for cinema projectors, and searchlights. It can be used as a catalyst for chemical reactions, and in jewelry. In fact, rhodium is a very common plating for inexpensive jewelry because it is extremely shiny and tarnish resistant. It is actually a very expensive metal however, only need a microscopically thin layer is needed. 

The Biology Department beam line includes a station for protein crystallography (with Supper oscillation camera and FAST TV diffractometer) and a station for small angle diffraction (with a three-circle goniostat and MWPC electronic area detector). The latter station may be available for optimised anomalous dispersion crystallographic studies. The optical design for each consists of a bent pre-mirror, double crystal monochromator and bent post-mirror the mirrors have rhodium coatings (Wise and Schoenborn 1982). 

Suppose that you need a coating of rhodium (a precious metal) on a part that is to be used as a mirror in a laser. Because rhodium is so expensive, you wish to deposit only 4.5 mg on the surface of the part. If you run an electrolytic apparatus for 5.0 min, what current do you need to deposit the desired amount from a solution containing Rh ions ... 

A piece of metal that measures 1.3 cm by 0.83 cm will have a coating of rhodium plated on its surface to serve as a mirror. The rhodium thickness will be 0.00030 mm, and the electrolyte contains Rh + ions. If the operating current of the electrolysis is... 

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