William Coblentz | |
---|---|
Born | November 20, 1873 North Lima, Ohio, U.S. |
Died | September 15, 1962 88) Washington, D.C., U.S. | (aged
Alma mater | |
Known for | Infrared radiometry and spectroscopy |
Spouse | |
Awards |
|
Scientific career | |
Fields | Physics |
Institutions | National Bureau of Standards |
William Weber Coblentz (November 20, 1873 – September 15, 1962) was an American physicist notable for his contributions to infrared radiometry and spectroscopy. [1]
William Coblentz was born in North Lima, Ohio to parents of German and Swiss descent. His mother (Catherine) died when Coblentz was just under three, leaving him temporarily with a family of just his younger brother (Oscar) and their father (David). However, the father remarried about 2 years later, and Coblentz appears to have admired his second mother (Amelia). Throughout Coblentz's childhood and adolescence, his family lived on farms, but apparently were never able to buy one of their own. The family's extremely modest circumstances led to a somewhat-delayed education for Coblentz, who did not finish high school (Youngstown, Ohio) until 1896, when he was 22 years old.
Coblentz entered the Case School of Applied Science, now Case Western Reserve University in the fall of 1896, and received his Bachelor of Science degree in physics in June, 1900. He went on to earn MS (1901) and PhD (1903) degrees from Cornell University in Ithaca, New York, staying two years beyond his doctoral time by working as a Research Fellow with support from the Carnegie Institution. In the spring of 1905, Coblentz accepted a position with the newly founded National Bureau of Standards (now the National Institute of Standards and Technology, NIST) in Washington, DC, where he spent his entire career. In 1905 he founded the Bureau's radiometry section, and headed it for 40 years until his retirement in 1945.
During the course of a long and productive career, Coblentz made many scientific contributions both of a pure and applied nature. Bibliographies of his work show that he had hundreds of scientific publications, talks, and abstracts to his credit. [2] He received a total of ten patents during his lifetime, the first being US Patent 1,077,219 for a solar cell invention to convert sunlight to electricity.
Coblentz's first publication, "Some Optical Properties of Iodine", was based on his PhD research. [3] On acquiring his doctorate, he soon began publishing regularly on problems related to infrared (IR) radiation, both those concerning spectroscopy and those concerning radiometry. For example, Coblentz was among the first, if not the very first, to verify Planck's Law [ citation needed ].
When Coblentz entered Cornell University, infrared spectroscopy was in what today would be considered an extremely primitive state. As a young Cornell researcher, Coblentz assembled and calibrated his own IR equipment, and extended the range of IR measurements to longer wavelengths than had ever been reached. By 1905 he had acquired hundreds of spectra by tedious point-by-point measurements with a prism instrument of his own construction. These were published in 1905 with large fold-outs charts (not available in the later reprints), and tables of wavelengths at which various materials absorbed IR light. [4] While such a massive spectral compilation itself was something of a tour de force, it is perhaps not the most important part of Coblentz's 1905 book. Instead, that honor probably goes to his generalization that certain molecular groupings, or functional groups in modern parlance, appeared to absorb specific and characteristic IR wavelengths. In time this would allow scientists to use a molecule's IR spectrum as a type of molecular fingerprint. This generalization had been hinted at in earlier work by others, but not with such a large amount of supporting data as Coblentz presented. Today, IR spectra are used in thousands of laboratories around the globe by scientists in many fields.
As an aside, Coblentz's early work on molecular spectra was not given the eager reception that hindsight might suggest. The reasons are numerous and have been explored by several authors. [5]
Coblentz had a long interest in astronomical problems. In 1913, he developed thermopile detectors and used them at Lick Observatory to measure IR radiation from 110 stars, and the planets Mars, Venus, and Jupiter. In this work he was assisted by Seth Nicholson, later of the Mt. Wilson Observatory. Extending this work, Coblentz and Carl Lampland, of the Lowell Observatory, measured large differences between the day and night temperatures on Mars, which implied a thin Martian atmosphere.
For his applications of IR detectors to astronomy, Coblentz is regarded as the founder of astronomical infrared spectroscopy. In recognition of his astronomical contributions, craters on the moon and Mars were named after him by the International Astronomical Union. [6]
Coblentz also made observations of solar eclipses, and published papers describing his work.
An inspection of Coblentz's bibliography shows that from about 1930 his research turned more toward measurements involving the ultraviolet (UV) region and away from infrared work. Much of this research had a distinctly bio-medical slant, such as his investigations of ultraviolet therapy (1938) and the production of skin cancer by UV exposure (1948).
Although Coblentz is remembered today mainly for his contributions to physics and astronomy, he also had interests in bioluminescence, atmospheric ozone, and, perhaps surprisingly, parapsychology. He appears to have brought the same energy to the latter field as he did to his other areas of interest.
Coblentz was elected a member of the National Academy of Sciences in 1930. [2]
Among the awards Coblentz received were the 1911 Howard N. Potts Medal from the Franklin Institute, the 1920 Janssen Medal from the French Academy of Sciences, and the 1937 Rumford Prize from the American Academy of Arts and Sciences. In 1945, shortly after retiring, Coblentz received the Frederic Ives Medal from the Optical Society of America.
The Coblentz Society, dedicated to the understanding and application of vibrational spectroscopy, is named in his honor, as is the Coblentz Medal. Coblentz was given membership card number 1 from the Society. [2] Coblentz died just before his 1905 work on infrared spectroscopy was reprinted, nearly 60 years after its first publication.
In his autobiography, From the Life of a Researcher (1951), William Coblentz described his typical day as long hours of laboratory research followed by evenings spent on data analysis and writing papers. [7] This left little time for socializing, and so it is not unexpected that Coblentz was over 50 before ever marrying. He wed Catherine Emma Cate of Vermont on June 10, 1924, and it is said that they spent their honeymoon in Flagstaff, Arizona while Coblentz was at the Lowell Observatory measuring planetary temperatures. Catherine Cate Coblentz achieved success as a writer of children's book, worked for a time at the National Bureau of Standards, and was instrumental in raising money to build the Cleveland Park Neighborhood Library in Washington, DC.
William Coblentz reportedly was plagued by periods of poor health, but he lived nearly 90 years. He is buried in Rock Creek Cemetery in Washington, DC alongside his wife and an infant daughter.
Infrared is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with waves that are just longer than those of red light, so IR is invisible to the human eye. IR is generally understood to include wavelengths from around 750 nm (400 THz) to 1 mm (300 GHz). IR is commonly divided between longer-wavelength thermal IR, emitted from terrestrial sources, and shorter-wavelength IR or near-IR, part of the solar spectrum. Longer IR wavelengths (30–100 μm) are sometimes included as part of the terahertz radiation band. Almost all black-body radiation from objects near room temperature is in the IR band. As a form of electromagnetic radiation, IR carries energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon.
Spectroscopy is the field of study that measures and interprets electromagnetic spectrum. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.
An optical spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the irradiance of the light but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light or a closely derived physical quantity, such as the corresponding wavenumber or the photon energy, in units of measurement such as centimeters, reciprocal centimeters, or electron volts, respectively.
Atomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions, at the scale of one or a few atoms and energy scales around several electron volts. The three areas are closely interrelated. AMO theory includes classical, semi-classical and quantum treatments. Typically, the theory and applications of emission, absorption, scattering of electromagnetic radiation (light) from excited atoms and molecules, analysis of spectroscopy, generation of lasers and masers, and the optical properties of matter in general, fall into these categories.
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in between visible radiation, which ranges from 380 to 750 nanometers, and submillimeter waves.
The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have 10 m (33 ft) aperture primary mirrors, and, when completed in 1993 and 1996, they were the largest optical reflecting telescopes in the world. They have been the third and fourth largest since 2006.
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects. A stellar spectrum can reveal many properties of stars, such as their chemical composition, temperature, density, mass, distance and luminosity. Spectroscopy can show the velocity of motion towards or away from the observer by measuring the Doppler shift. Spectroscopy is also used to study the physical properties of many other types of celestial objects such as planets, nebulae, galaxies, and active galactic nuclei.
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space–what they are, rather than where they are", which is studied in celestial mechanics.
Absorption spectroscopy is spectroscopy that involves techniques that measure the absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum.
Ira Sprague Bowen was an American physicist and astronomer. In 1927 he discovered that nebulium was not really a chemical element but instead doubly ionized oxygen.
Near-infrared spectroscopy (NIRS) is a spectroscopic method that uses the near-infrared region of the electromagnetic spectrum. Typical applications include medical and physiological diagnostics and research including blood sugar, pulse oximetry, functional neuroimaging, sports medicine, elite sports training, ergonomics, rehabilitation, neonatal research, brain computer interface, urology, and neurology. There are also applications in other areas as well such as pharmaceutical, food and agrochemical quality control, atmospheric chemistry, combustion research and knowledge.
Curtis Judson Humphreys was an American physicist born in Alliance, Ohio, USA and educated at the University of Michigan. He was chief of the Radiometry Section of the U.S. Navy during the 1940s. He is famous for discovering the Humphreys series of the hydrogen atom.
Heinrich Rubens was a German physicist. He is known for his measurements of the energy of black-body radiation which led Max Planck to the discovery of his radiation law. This was the genesis of quantum theory.
Gerhart "Gerry" Neugebauer was an American astronomer known for his pioneering work in infrared astronomy.
Richard C. Lord (1910–1989) was an American chemist best known for his work in the field of spectroscopy.
Anders Jonas Ångström was a Swedish physicist and one of the founders of the science of spectroscopy.
Modern spectroscopy in the Western world started in the 17th century. New designs in optics, specifically prisms, enabled systematic observations of the solar spectrum. Isaac Newton first applied the word spectrum to describe the rainbow of colors that combine to form white light. During the early 1800s, Joseph von Fraunhofer conducted experiments with dispersive spectrometers that enabled spectroscopy to become a more precise and quantitative scientific technique. Since then, spectroscopy has played and continues to play a significant role in chemistry, physics and astronomy. Fraunhofer observed and measured dark lines in the Sun's spectrum, which now bear his name although several of them were observed earlier by Wollaston.
Dale P. Cruikshank is an astronomer and planetary scientist in the Astrophysics Branch at NASA Ames Research Center. His research specialties are spectroscopy and radiometry of planets and small bodies in the Solar System. These small bodies include comets, asteroids, planetary satellites, dwarf planets, and objects in the region beyond Neptune. He uses spectroscopic observations made with ground-based and space-based telescopes, as well as interplanetary spacecraft, to identify and study the ices, minerals, and organic materials that compose the surfaces of planets and small bodies.
Guido Münch Paniagua was a Mexican astronomer and astrophysicist.
R. Robert Brattain was an American physicist at Shell Development Company. He was involved in a number of secret projects during World War II. He is recognized as one of America's leading infrared spectroscopists for his work in designing several models of spectrophotometer, and for using the infrared spectrophotometer to determine the β-lactam structure of penicillin. His instrumentation work was essential to the subsequent study and understanding of structures in organic chemistry.
coblentz, william weber.
Copies of most of Coblentz's books are listed as being in the libraries of the University of Maryland and the American Institute of Physics, both in College Park, Maryland (USA), not far from where Coblentz lived, worked, and died.