Graves from Göttingen: Richard Adolf Zsigmondy

Nanotechnology often seems like it belongs in the pages of a science fiction book, but it’s been studied for well over a hundred years. It is now known that the Romans used nanotechnology to make such things as the fascinating Lycurgus Cup, and scientists from the 17th century alchemist Daniel Sennert to Michael Faraday have speculated on solutions of nanoparticles. However, the person who made the real breakthrough was a relatively unknown scientist of Hungarian descent, born in Vienna on April 1, 1865. His name was Richard Adolf Zsigmondy.

Zsigmondy’s father was an academic and a famous dentist who worked to popularize dentistry in Austria and even invented some surgical instruments. Zsigmondy had two brothers, and their father encouraged his sons to pursue academic interests. The boys’ mother, on the other hand, encouraged them to pursue the arts and their own interests, as well as to lead an active outdoor life.

Zsigmondy began learning quantitative analysis from the medical faculty at the University of Vienna and then went on to the Technical University of Vienna, where he studied chemistry. Later, he earned a doctorate in organic chemistry at the University of Munich. Soon, he accepted a position at the University of Berlin as assistant to Professor Kundt, the man who first sparked in him an interest in the coloration of glass. Zsigmondy was invited to teach at the Graz University of Technology, where he continued to study glass pigmentation, especially the “Purple of Cassius”—a pigment used to create the popular “ruby glass.” You might recognize ruby glass if you’ve seen Werner Herzog’s film Hart of Glass, in which all the actors but one are acting while being hypnotized. The color of this glass is created by particles of gold suspended in the pigment solution. In 1897, Zsigmondy accepted a job working for the Schott glassworks in Jena, Germany, where he developed a type of milk glass—a white, translucent glass. Here, he continued his work in glass pigmenting and luster colors.

Luster colors, a type of pigmentation often used for glass, create color and iridescence because they are particles of metals suspended in the glass or glaze. These liquids, called colloidal liquids, contain particles called sols, which are invisible to the eye but color the solution. “Purple of Cassius,” the pigment Zsigmondy had been studying, is a colloid of gold particles in tin oxide. The existence of these particles was known, but the mystery remained as to why there was differentiation in the colors of different colloid solutions. Zsigmondy eventually debunked Faraday’s theory, which was that the color changed because of variations in the size of the particles.

After he left the Schott glassworks, Zsigmondy pursued private research in colloid solutions, and, with the help of the optical physicist Heinrich F. W. Seidentopf, began to push the limits of the microscope. In the early 20th century, the power of microscopes had improved, using techniques such as higher wavelengths and immersion oils with high refractive indices. However, Zsigmondy and Seidentopf approached microscopy in their own unique ways. The two scientists put the light source at a right angle to the line of vision and set the sample against a dark backdrop. That way, Zsigmondy could see the cones of light against the backdrop, thrown by single particles in solution. Their invention, the ultramicroscope, could distinguish particles as small as four nanometers. To give some scale, that is the width of 12 atoms of gold, and a human hair is around 100,000 nanometers thick. With the ultramicroscope, Zsigmondy was able to show that it wasn’t the size of gold sols that changed the color of the light, as Faraday had thought, but their shape. Thus, these two men had enabled and begun the science of nanotechnology. Zsigmondy won the 1925 Nobel Prize in Chemistry for his work on colloidal solutions.

Zsigmondy lived in Göttingen, where he worked as the Director of the Institute of Inorganic Chemistry, from 1907 to his death of arteriosclerosis in Feb., 1929.