![]() Back in 1916, Albert Einstein had deduced theoretically the existence of stimulated emission–the process by which electromagnetic waves of the right frequency can “stimulate” an excited atom or molecule to fall to a lower energy state and emit more waves. But in the early 1950s, Charles Townes, then at Columbia University in New York City, had the idea that molecules themselves would make good emitters of the desired wavelengths, if only he could persuade large numbers of molecules to emit en masse. Vacuum tubes and related devices, used in radar, are impractical for producing sub-centimeter wavelength radiation. When atomic bonds inside a molecule flip between slightly different forms, they often absorb or emit centimeter- or millimeter-band radiation. But the path from theory to application was far from straightforward, and it took ingredients from many different disciplines for these theoretically simple devices to achieve practicality.Īfter World War II, radar scientists looking for ways to generate electromagnetic radiation at wavelengths shorter than one centimeter began collaborating with physicists who wanted to use such radiation to investigate molecular structure. The maser–the name stands for “microwave amplification by stimulated emission of radiation”–in turn depended on an insight that came from Albert Einstein almost 40 years earlier. ![]() The ubiquitous laser, appearing today in supermarket checkout machines, CD players, and eye surgeon’s offices, developed out of the maser, which was first described in Physical Review papers published in 19. In honor of the World Year of Physics, which commemorates Einstein’s “miraculous year” in 1905, we’re presenting papers from the Physical Review archive related to Einstein’s accomplishments. Charles Townes and his colleagues were the first to build a “maser,” which operated in the microwave frequency range.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |