Gold (Aurum) is a metallic element with the symbol of Au and the atomic number of 79.

The simple substance (free form) of gold, commonly known as gold, is a precious metal, which has been used as currency, preservation and jewelry for many centuries. In nature, gold exists in the form of simple substance in gold nuggets or rocks, underground veins and alluvium.

Conductive substance of electron microscope

Gold or an alloy of gold and palladium plays a conductive role in scanning electron microscopy for biological samples and other non-conductive substances such as plastics and glass. The coating was added by argon plasma sputtering.

The high conductivity of gold leads the charge to the ground, and its high electron density makes the scanning electron microscope electron beam have the ability to stop electrons, which helps to limit the depth of the electron beam penetrating the sample.

This is helpful to improve the measurement accuracy of the sample position and its surface shape, and improve the spatial resolution of the image. When gold is irradiated by electron beam, it will also produce secondary emission. These low-energy electrons are usually used as the signal source of scanning electron microscope.