Pinchbeck (alloy) Pinchbeck (alloy) Pinchbeck is a form of brass, an alloy of copper and zinc, mixed in proportions so that it closely resembles gold in appearance. It was invented in the 18th century by Christopher Pinchbeck, a London clockmaker. Since gold was only sold in 18-carat quality at that time, the development of pinchbeck allowed ordinary people to buy gold 'effect' jewellery on a budget. The inventor allegedly made pinchbeck jewellery clearly labelled as such. Pinchbeck jewellery was used in places like stagecoaches where there was a risk of theft. Later dishonest jewellers passed pinchbeck off as gold; over the years
Alloy broadening is assumed that no clustering occurs within the alloy. Then, for a binary alloy of the form <chem>A_{1-x}B_{x}</chem>, e.g. <chem>Si_{1-x}Ge_{x}</chem>, the standard deviation of the composition is given by : where formula_2 is the number of atoms within the excitons' volume, i.e. formula_3 with formula_4 being the atoms per volume. In general, the band gap energy formula_5 of a semiconducting alloy depends on the composition, i.e. formula_5. The band gap energy can be considered to be the fluorescence energy. Therefore, the standard deviation in fluorescence is As the alloy broadening belongs to the group of inhomogeneous broadenings the line shape