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In 1948 Apker, working with E. A. Taft and J. E. Dickey, he completed experiments that confirmed Condon's theory. The main discovery made was that photoelectrons from some semiconductors moved much slower than photoelectrons from metals with the same
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filament for a set amount of time, and the filament is then rapidly heated. The gas adsorbed onto the filament is released, and the resulting pressure burst can be measured. Though very time-consuming, the flash filament method was later used for
374:, coloring the crystals at photon energies where they are usually transparent. Additionally, the absorption of visible radiation can free trapped electrons inside the crystal and produce photoconductivity.
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Apker found that in addition to visible radiation, near-ultraviolet radiation also produces photoconductivity. Deeper into the ultraviolet spectrum, however, potassium iodide has a strong
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231:. On July 5, 1970, he was found by his wife, suffering from a gunshot wound to the head on the driveway of his home. He was taken to a hospital in Schenectady, where he later died.
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http://fultonhistory.com/Newspaper%2018/Troy%20NY%20Times%20Record/Troy%20NY%20Times%20Record%201970/Troy%20NY%20Times%20Record%201970%20-%202061.pdf
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should behave in a different way than those emitted from other types of matter, and a very similar theory was advanced by
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Apker followed up his work on the photoelectric effect with an investigation of the photoelectric properties of the
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280:, an unexpected result which was used to increase understanding of the electronic structure of semiconductors.
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Apker, L.; Taft, E.; Dickey, J. (1953). "Electron
Scattering and the Photoemission from Cesium Antimonide".
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Vacuum science and technology: pioneers of the 20th century : history of vacuum science and technology
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Apker, L.; Taft, E.; Dickey, J. (1948). "Photoelectric
Emission and Contact Potentials of Semiconductors".
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with remarkably high efficiency, and these excited electrons are excited from the crystals in
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in memory of Apker. The award is presented to two college undergraduates each year.
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ions can be removed and their vacant places will be filled by electrons. Called "
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Apker, L.; Taft, E. (1951). "Exciton-Enhanced
Photoelectric Emission from
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In 1978, Apker's wife and colleague Jean Dickey Apker established the
393:. Apker observed the same sort of behavior in other crystals such as
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Apker, L. (1948). "Surface
Phenomena Useful in Vacuum Technique".
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degree in 1937. He then commenced graduate studies there under
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science. In 1948 he developed the flash filament method for
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385:. These excitons transfer energy to the electrons in the
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Apker, L.; Taft, E. (1950). "Photoelectric
Emission from
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due to the formation of chargeless particles called
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While at
General Electric, he began to research the
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219:in 1941. Also in 1941, he began working for the
260:, while verifying the photoelectric equations of
691:Oliver E. Buckley Condensed Matter Prize winners
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358:. In potassium iodide, an ionic crystal, some
643:. American Physical Society. 1982. p. 83.
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641:Bulletin of the American Physical Society
547:Journal of the Optical Society of America
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612:. American Vacuum Society. p. 142.
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169:Oliver E. Buckley Condensed Matter Prize
90:Oliver E. Buckley Condensed Matter Prize
696:Suicides by firearm in New York (state)
329:. In this method, a gas is allowed to
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288:Apker was also active in the field of
240:Photoelectric effect in semiconductors
199:, along with fellow graduate students
132:(June 11, 1915 – July 5, 1970) was an
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187:on June 11, 1915, Apker attended the
456:Industrial and Engineering Chemistry
221:General Electric Research Laboratory
118:General Electric Research Laboratory
681:Scientists from Rochester, New York
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13:
14:
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582:McGraw-Hill Modern Men of Science
159:and discovered the phenomenon of
676:American experimental physicists
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340:thermal desorption spectroscopy
211:, and others. He received his
16:American experimental physicist
686:University of Rochester alumni
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584:. McGraw-Hill. pp. 12–13.
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252:when exposed to some types of
248:, which causes matter to emit
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391:exciton-induced photoemission
161:exciton-induced photoemission
139:. Along with his colleagues
294:measuring very low pressures
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167:. In 1955, he received the
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580:Jay E. Greene, ed. (1966).
514:-Centers in RbI near 85K".
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411:American Physical Society
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254:electromagnetic radiation
173:American Physical Society
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366:," these defects absorb
447:10.1103/PhysRev.74.1462
319:{\displaystyle 10^{-}8}
258:Robert Andrews Millikan
189:University of Rochester
80:University of Rochester
606:P. A. Redhead (1994).
559:10.1364/JOSA.43.000078
538:10.1103/PhysRev.81.698
503:10.1103/PhysRev.79.964
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137:experimental physicist
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284:Flash filament method
61:Schenectady, New York
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246:photoelectric effect
108:Experimental physics
530:1951PhRv...81..698A
495:1950PhRv...79..964A
468:10.1021/ie50461a016
439:1948PhRv...74.1462A
185:Rochester, New York
43:Rochester, New York
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197:Lee Alvin DuBridge
619:978-1-56396-248-6
479:-Centers in KI".
407:LeRoy Apker Award
372:ultraviolet light
205:Esther M. Conwell
147:, he studied the
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98:Scientific career
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193:Bachelor of Arts
165:potassium iodide
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426:Physical Review
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379:absorption line
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209:Robert H. Dicke
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76:Alma mater
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266:semiconductors
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201:Ernest Courant
191:, receiving a
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157:semiconductors
130:LeRoy W. Apker
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39:June 11, 1915
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623:. Retrieved
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417:Bibliography
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395:barium oxide
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151:emission of
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114:Institutions
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55:(1970-07-05)
53:July 5, 1970
671:1970 deaths
661:1915 births
256:. In 1916
225:Schenectady
145:Jean Dickey
68:Nationality
23:LeRoy Apker
655:Categories
567:References
489:(6): 964.
141:E. A. Taft
35:1915-06-11
625:March 15,
387:F-Centers
364:F-Centers
309:−
272:in 1938.
250:electrons
179:Biography
153:electrons
383:excitons
335:tungsten
235:Research
229:New York
183:Born in
134:American
71:American
526:Bibcode
491:Bibcode
435:Bibcode
409:of the
368:visible
217:physics
171:of the
616:
401:Legacy
360:iodide
331:adsorb
290:vacuum
104:Fields
92:(1955)
86:Awards
213:Ph.D.
155:from
627:2011
614:ISBN
370:and
327:Torr
143:and
50:Died
29:Born
555:doi
534:doi
499:doi
464:doi
443:doi
223:in
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