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Recent news that x-ray spectroscopy is being introduced in forensic applications by scientists at Massachusetts' Thermo Scientific Laboratories proves that everything old becomes new again. X-rays were discovered just over a century ago; it's interesting to see how one hundred years of scientific advances have turned a simple discovery into a cutting-edge technology.
Wilhelm Roentgen, a German physicist, discovered x-rays, winning a Nobel Prize for the discovery in 1901. Thomas Edison jumped on the field in the early 1900s and developed the first fluoroscope for medical examinations. His lab assistant Clarence Dally had the bad habit of testing x-rays on his own hands: He developed such bad cancers in them that both arms had to be amputated.
Meanwhile, British physicist Charles Barkla's x-ray experiments took a different direction, focusing on refining the laws of x-ray scattering. His work, which includes discovering the correlation between x-ray radiation and atomic weight, formed the beginning of x-ray spectroscopy. He won the 1917 Nobel Prize in Physics for his discovery. Not to be outdone, his compatriot Henry Gwyn Jeffreys Moseley took x-ray spectroscopy a step further; his work led to the reorganization of the periodic table by atomic number instead of atomic weight.
The hard work in x-ray spectroscopy moved from England to Sweden as World War II loomed, and Manne Siegbahn delved into the field at the University of Uppsala. His work led to the Siegbahn notation that delineated the spectral lines that characterize elements and formed the foundation for the nomenclature of spectroscopy. He won the Nobel Prize in 1924 for his discoveries in x-ray spectroscopy, and he also fathered the next generation of Nobel Prize winners in the field—literally.
His son Kai Siegbahn went on to develop Electron Spectroscopy for Chemical Analysis (ESCA), which is now known as x-ray photoelectron spectroscopy (XPS). Kai won his Nobel Prize in 1981 to honor his efforts establishing XPS as an analytical tool.
From concept to space travel in 100 years! X-Ray Spectroscopy is now used with the James Webb Telescope. (Image Credits: NASA)
Britain reclaimed the x-ray spectroscopy mantle when David Turner, an Oxford physicist, developed ultraviolet photoelectron spectroscopy, or UPS, using helium as a photon source. His method was later applied to solid surfaces, where it was used to study adsorption and formed some of the foundations of quantum chemistry. UPS started to fall out of favor for more advanced x-ray spectroscopy techniques, but advances in synchrotron light sources are powering a revival.
Now, of course, x-ray spectroscopy is an essential tool behind some of the most important scientific discoveries of the 21st century. While other spectroscopy methods like near-infrared are involved in the glamorous applications, like exploring the origins of the universe with the James Webb Space Telescope, XPS will likely remain the spectroscopy workhorse of humble German beginnings.