September 24 is Georges Claude’s birthday. Claude was the French engineer and inventor that created neon lights.
Neon lights work by passing a current through a sealed tube of neon gas. The electrical current ionizes the neon atoms enough so when the electron returns to its ground state, it emits a photon. These photons are visible as bright orange light.
Sign manufacturers jumped on this new lighting method, but the color choice seemed limited. You could have any color you wanted, as long as it was orange. It was quickly discovered that if you use a different gas, you got different colors. Mercury vapor will glow with a light blue color. Argon gas is mixed with other elements to give a very bright glow. For white light, carbon dioxide gas gave the best results. In all, there are 150 different colors available to the ‘neon’ sign maker.
An alternate method of achieving color is to coat the glass tube with various phosphor powders. This works in much the same way as a fluorescent light. Higher energy light excites the atoms in the coating and transmits a lower energy wavelength of light. Depending on the powder used, almost any color can be produced. For example, if you mix a little phosphor with argon, the light will shine with a bright yellow glow.
Neon lighting is an excellent example of science and art mixing together. Bending glass tubes and sealing electrical connectors and various gases to form an image visible from a long way away takes both talent and skill. Claude’s invention redefined outdoor landscapes but the art is slowly dying away as less expensive and more efficient LED lighting is replacing those bright neon lights.
I found an interesting documentary about the decline of neon lighting in Hong Kong, a city famous for its neon lights. It contains a few sign makers talking about the business of sign making and how they go about constructing their signs. It is 12 minutes long and a little sad towards the end, but very informative.
Notable Science Events for September 24
1978 – Ida (Tacke) Noddack died.
Noddack was a German chemist who, with her husband Walter, discovered the element rhenium. Rhenium was the second to last naturally occurring stable element discovered. It was isolated from platinum ore and the mineral columbite. The group announced they had found the element technetium when they bombarded columbite with electrons, but their results were never verified. They named their discovery masurium after the Masuria in Eastern Prussia.
1945 – Hans Geiger died.
Geiger was a German physicist who is best known for the invention of the Geiger counter. The Geiger counter is a particle detector that measures ionizing radiation intensity. Ionizing radiation enters a metal tube containing an inert gas and a charged filament wire. When the radiation interacts with the inert gas, it ionizes the gas. The charged gas ions are attracted to the charged wire. The voltage change this generates is measured and counted. The Geiger counter keeps track of these voltage changes with an audible click, a running counter, or both.
Together with Ernest Marsden, he conducted the Gold foil experiment that first detected the presence of the atomic nucleus.
1905 – Severo Ochoa was born.
Ochoa was a Spanish biochemist who shares the 1959 Nobel Prize in Medicine with Arthur Kornberg for outlining the mechanisms involved in the synthesis of DNA and RNA. Ochoa discovered an enzyme in bacteria that allowed him to synthesize ribonucleic acid or RNA. He discovered the enzyme while researching high-energy phosphates. The enzyme’s main function was to degrade RNA but under laboratory conditions, it could run the process in reverse.
1904 – Niels Ryberg Finsen died.
Finsen was a Danish physician who was awarded the 1903 Nobel Prize in Medicine for his treatment of diseases with light radiation. He started investigations in the treatment of diseases with sunlight and heat lamps. He later devised new treatments for small pox using a red light and a treatment for lupus.
1898 – Howard Walter Florey was born.
Florey was an Australian pathologist who shared the 1945 Nobel Prize in Medicine with Ernst Boris Chain and Walter Fleming for the discovery of penicillin and its curative effects on various diseases. Florey and Chain discovered a method to isolate and purify penicillin for clinical use.
1895 – André F. Cournand was born.
Cournand was a French doctor who shared the 1956 Nobel Prize in Medicine with Werner Forssmann and Dickinson Richards for their work with heart catheters and their effect on circulation. He worked with Richards to perfect Forssmann’s surgical technique where a catheter is inserted at the elbow to reach the heart. This allowed a doctor to diagnose several heart conditions without major invasive surgery. They also applied this technique for the pulmonary artery to diagnose lung diseases.
1870 – Georges Claude was born.
1541 – Paracelsus died.
Paracelsus was born Phillip von Hohenheim and later became Theophrastus Philippus Aureolus Bombastus von Hohenheim. He was a German-Swiss Renaissance alchemist and doctor who believed medical training should be based on observations and experience and replaced many herbal remedies with chemical substitutes. He believed illnesses had external causes instead of unbalances in the bodily humours. He took on the name Paracelsus to show he was ‘greater than Celsus’, the Roman doctor that wrote the authoritative encyclopedia on medicine. He gained fame after he published his Die Grosse Wundartznei (The Great Surgery Book).