[ { "id": "authors:be9p3-mya20", "collection": "authors", "collection_id": "be9p3-mya20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151211-131953252", "type": "article", "title": "University Basic Research", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "The nation's program of basic research\nin science is at a critical juncture.\nIts future progress is by no means\nassured, and much will depend on the\noutcome of the debates now in progress.\nThese debates are going on not\nonly in scientific circles but also in\nthe public press, in the halls of Congress,\nand in the offices and conference\nrooms of many government agencies.\nPressures for reducing or leveling\noff research budgets are evident.", "doi": "10.1126/science.157.3789.648", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1967-08-11", "series_number": "3789", "volume": "157", "issue": "3789", "pages": "648-650" }, { "id": "authors:e4keq-h3v85", "collection": "authors", "collection_id": "e4keq-h3v85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151214-080949983", "type": "article", "title": "Research: Vexatious Issues between Government and University", "author": [ { "family_name": "Greene", "given_name": "W. A.", "clpid": "Greene-W-A" }, { "family_name": "Walker", "given_name": "Eric A.", "clpid": "Walker-E-A" }, { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Lippard", "given_name": "Vernon W.", "clpid": "Lippard-V-W" } ], "abstract": "In \"Bureau of the Budget cost sharing and effort reports\" (Letters, 17 Feb.) Lang has correctly identified several problems of concern to research administrators and the university community, but I feel he has misconstrued\nboth the reason for and possible consequences arising from submission of time and effort reports.", "doi": "10.1126/science.155.3769.1489", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1967-03-24", "series_number": "3769", "volume": "155", "issue": "3769", "pages": "1489-1492" }, { "id": "authors:1k69v-r3h11", "collection": "authors", "collection_id": "1k69v-r3h11", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151124-155404714", "type": "article", "title": "Research Overhead", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Kaplan", "given_name": "Norman", "clpid": "Kaplan-N" } ], "abstract": "DuBridge and Kaplan exchange views on overhead payments for basic research in private universities.", "doi": "10.1126/science.132.3441.1746", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1960-12-09", "series_number": "3441", "volume": "132", "issue": "3441", "pages": "1746-1749" }, { "id": "authors:eh7qj-9za57", "collection": "authors", "collection_id": "eh7qj-9za57", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170728-140602887", "type": "article", "title": "Science and National Security", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "We are sometimes inclined to think that the phenomenon of science being of service to the nation is a new development of recent years-say since 1940. However, science has always been a national asset and has always been in the nation's service. Science and technology have been among the decisive influences that have improved the lot of the common people and thus made this nation fine and strong.", "doi": "10.1126/science.120.3131.1081", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1954-12-31", "series_number": "3131", "volume": "120", "issue": "3131", "pages": "1081-1085" }, { "id": "authors:p0w1y-pnx31", "collection": "authors", "collection_id": "p0w1y-pnx31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170822-171728635", "type": "article", "title": "The goals of University research", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "The university is viewed as an institution for sharpening men's intellectual abilities and focusing them on mankind's basic problems. Research seeks knowledge as a step toward understanding.", "doi": "10.1109/EE.1954.6438967", "issn": "0095-9197", "publisher": "AIEE", "publication": "Electrical Engineering", "publication_date": "1954-09", "series_number": "9", "volume": "73", "issue": "9", "pages": "790-793" }, { "id": "authors:0c1q0-9vs03", "collection": "authors", "collection_id": "0c1q0-9vs03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170822-174858933", "type": "article", "title": "Scientific Manpower", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "The most conservative figures on the shortage of engineers suggests that this shortage is now around 95,000 and will reach 156,000 by 1955. A less conservative view of the figures available suggests that this situation might be much worse. The number of new engineers now being produced each year may be actually less than the number lost to engineering activities through death, military service, and transfer to nonengineering duties. We might be 300,000 engineers short by 1955. Since it takes four years to train an engineer, all we can do during the next four years is to make better use of the engineering manpower which will be available. But high-school students are being discouraged from entering the fields of science and engineering by misleading statements of prominent people that science and engineering are the cause of the world's troubles. Engineers and scientists can do much to remove this misapprehension by pointing out that scientists and engineers also work for human welfare and that science and engineering are helping to solve the world's troubles rather than causing them. This must be done and additional scholarship funds be made available before the downward trend in engineering and science enrollments is reversed.", "doi": "10.1109/JRPROC.1952.274094", "issn": "0096-8390", "publisher": "IRE", "publication": "Proceedings of the IRE", "publication_date": "1952-08", "series_number": "8", "volume": "40", "issue": "8", "pages": "900-901" }, { "id": "authors:9axkt-59713", "collection": "authors", "collection_id": "9axkt-59713", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBrmp48", "type": "article", "title": "R. A. Millikan and the California Institute of Technology", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "If one examines a list of the publications of R.A. Millikan, arranged in chronological order, one finds essentially no break in continuity from 1910 to the present, except for the war years, 1918-20 and 1941-45. In particular, the years 1921 to 1940 were among the most productive of his career. One would never suppose that in 1921 Dr. Millikan assumed an administrative task of such great magnitude that it would have effectively stopped the research activities of most ordinary men. \n\nMoreover, one cannot explain this phenomenon by the assumption that Dr. Millikan gave but brief attention to his new administrative duties. On the contrary, his new tasks were carried forward with such zeal, vigor, and effectiveness that one who examines the history of his administrative achievements during the two decades after 1921 can only be astonished that a single man could carry such a burden even though he gave it all of his time and attention. His successor in these tasks hardly dares hope that he can ever resume a scientific career. \n\nIn 1920 the name of a small technical school in Pasadena, California was changed from Throop College of Technology to the California Institute of Technology. This change in name was the external evidence for the culmination of the dreams and practical efforts of Dr. George Ellery Hale, the founder and, for many years, the Director of the Mount Wilson Observatory of the Carnegie Institution of Washington. By 1908, Dr. Hale had seen the possibilities for establishing a great and unique center of pure and applied science in Southern California, and he started active work toward this goal. In 1913 he enlisted the aid of Dr. A.A. Noyes, distinguished chemist of the Massachusetts Institute of Technology, who came to Throop College first on a part-time basis, and in 1919 assumed full-time direction of the Laboratory of Chemistry.", "doi": "10.1103/RevModPhys.20.7", "issn": "0034-6861", "publisher": "American Physical Society", "publication": "Reviews of Modern Physics", "publication_date": "1948-01", "series_number": "1", "volume": "20", "issue": "1", "pages": "7-9" }, { "id": "authors:eefhk-qvp02", "collection": "authors", "collection_id": "eefhk-qvp02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBrsi46", "type": "article", "title": "History and Activities of the Radiation Laboratory of the Massachusetts Institute of Technology", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "The Radiation Laboratory of the Radiation Laboratory of the Massachusetts Institute of Technology, the largest wartime laboratory devoted to radar research and development and the largest single enterprise of the National Defense Research Committee, is demobilizing after five years of intense work heretofore shrouded by tight military security. Operating as a quasi-governmental agency, the Radiation Laboratory participated in one of the most extraordinary cooperative scientific efforts in history -- an enterprise which included many British government and industrial laboratories, several U.S. Army and Navy laboratories, and a host of U.S. industrial laboratories, large and small. From the combined effort of all came the development of a radar industry which provided Allied fighting forces with an amazing array of radar equipments. Individually, each was far in advance of any radar the enemy nations possessed; collectively, our radar revolutionized many phases of modern warfare and contributed significantly to the Allied victory.", "doi": "10.1063/1.1770386", "issn": "0034-6748", "publisher": "American Institute of Physics", "publication": "Review of Scientific Instruments", "publication_date": "1946-01", "series_number": "1", "volume": "17", "issue": "1", "pages": "1-5" }, { "id": "authors:2d41s-1mg43", "collection": "authors", "collection_id": "2d41s-1mg43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr40", "type": "article", "title": "Radioactive isotopes of Sr, Y and Zr", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Marshall", "given_name": "John", "clpid": "Marshall-J" } ], "abstract": "Radioactive isotopes formed by bombardment of Rb, Sr and Y by protons, deuterons and neutrons are reported. The following are the periods and assignments: 2.75-hr. (Sr87*, e-, \u03b3); 70-min. (Sr85, e-, \u03b3); 66-day (Sr85, K, \u03b3); 80-hr. (Y87, K); 14-hr. (Y87, e-, \u03b3); 105-day (Y86, K, \u03b3); 4.5-min. (Zr89, \u03b3); 78-hr. (Zr89, \u03b2+). (In each case e- means conversion electrons, not nuclear \u03b2-rays.) The electron spectrum of the 2.75-hr. Sr87* shows a single line at 360 kev and this period is shown to grow from the 80-hr. Y87, but not from the 14-hr. isomer.", "doi": "10.1103/PhysRev.58.7", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1940-07-01", "series_number": "1", "volume": "58", "issue": "1", "pages": "7-11" }, { "id": "authors:x2f4s-ard08", "collection": "authors", "collection_id": "x2f4s-ard08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:LEPpr40", "type": "article", "title": "Electron emission into dielectric liquids", "author": [ { "family_name": "LePage", "given_name": "Wilbur R.", "clpid": "LePage-W-R" }, { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "The current between polished nickel electrodes immersed in pure toluene has been measured as a function of electric field (over the range 0 to 250,000 volts/cm) and of temperature (from - 15 to 70\u00b0C). The Richardson lines are straight but show a very small slope (0.05 to 0.4 ev) and a small value of the constant A (10^-9 to 10^-11 amp./cm^2 deg.^2). The logi vs. E1 / 2 curves show a slope about twice the value e3 / 2 / D1 / 2kT predicted by the simple Schottky theory, but in agreement with the theory of Baker and Boltz. It is found however that there are serious objections to this theory, and the agreement with it is probably accidental. The situation is in fact too complex to be handled by a simple theory. It is suggested that for the low potential barrier present at the metal-dielectric interface a combination of thermionic and field currents would be expected which would account qualitatively for the observed behavior.", "doi": "10.1103/PhysRev.58.61", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1940-07-01", "series_number": "1", "volume": "58", "issue": "1", "pages": "61-66" }, { "id": "authors:wxdd0-tnc73", "collection": "authors", "collection_id": "wxdd0-tnc73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr39", "type": "article", "title": "A radioactive isomer of Sr87", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Marshall", "given_name": "John", "clpid": "Marshall-J" } ], "abstract": "In connection with studies soon to be reported of the radioactive isotopes of Sr and Y we have given particular attention to a period of 2.7\u00b10.2 hours which appears to be associated with an excited state of stable Sr87.", "doi": "10.1103/PhysRev.56.706", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1939-10-01", "series_number": "7", "volume": "56", "issue": "7", "pages": "706-707" }, { "id": "authors:36j27-t5211", "collection": "authors", "collection_id": "36j27-t5211", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr38", "type": "article", "title": "Proton induced radioactivities", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Barnes", "given_name": "S. W.", "clpid": "Barnes-S-W" }, { "family_name": "Buck", "given_name": "J. H.", "clpid": "Buck-J-H" }, { "family_name": "Strain", "given_name": "C. V.", "clpid": "Strain-C-V" } ], "abstract": "Results are tabulated of the radioactivities produced by 4 Mev protons in targets of 7N, 8O, 20Ca, 24Cr, 27Co, 30Zn, 34Se, 42Mo, 46Pd, 48Cd, 49In. In most cases the reactions are of the p-n type, and lead to isotopes which emit either + or - electrons. A detailed study was made of O, Zn and Se. The reaction O18(p, n)F18 (107 min.) shows a threshold at 2.56 Mev and a positron energy of 0.74 Mev in good agreement with the energy relations. The cross section for the reaction at 4 Mev is about 2\u00d710^-25 cm^2 and there is a resonance maximum at 3.55 Mev. The cross section for the reaction O16(p, \u03b3)F17 is 4000 times smaller. The isomeric Br80 periods (17.4 min. and 4.45 hr.) are observed in the reaction Se80(p, n)Br80. At 4 Mev the ratio of the short to long period activities for infinite bombardment is about 15 but the thresholds are at about 3.0 and 3.2 Mev, respectively. The cross section for the reaction is about 0.6\u00d710^-26 cm^2 at 4 Mev.", "doi": "10.1103/PhysRev.53.447", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1938-03-15", "series_number": "6", "volume": "53", "issue": "6", "pages": "447-453" }, { "id": "authors:qa18v-jgc94", "collection": "authors", "collection_id": "qa18v-jgc94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBjap38", "type": "article", "title": "Some Aspects of Nuclear Physics of Possible Interest in Biological Work", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "In selecting a title for this paper I have endeavored to choose one which would create no illusions as to its purpose or content. It is my purpose only to review (in a very elementary way) some of the aspects of nuclear physics which give promise of providing useful tools in biological research. I shall attempt to indicate a few of the types of problems to which these tools may be applied. I am not reporting any research which has been carried on in this field. I cannot claim originality for any of the suggestions I am going to make concerning biological problems, since they are all either more or less obvious or else have been proposed by various workers in this field (1). Note that these are only suggestions as to possible problems to which these new tools may be applied; not predictions of any definite results which may be obtained. It is as difficult to make predictions in this field now as it would have been thirty-five years ago to predict the biological applications of x-rays and radioactivity.", "doi": "10.1063/1.1710407", "issn": "0021-8979", "publisher": "American Institute of Physics", "publication": "Journal of Applied Physics", "publication_date": "1938-03", "series_number": "3", "volume": "9", "issue": "3", "pages": "178-186" }, { "id": "authors:3jck6-x9e43", "collection": "authors", "collection_id": "3jck6-x9e43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBrsi38", "type": "article", "title": "The physics of solids", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" } ], "abstract": "I have been asked to review before this group some of the developments in physics during the past twenty-five years, particularly as they relate to our understanding of the physics of solids. I am going to address my remarks particularly to those who have not been in a position to follow these developments but who are interested in getting a general idea of the new ideas which have proved of value in understanding and correlating the properties of solids.", "doi": "10.1063/1.1752342", "issn": "0034-6748", "publisher": "American Institute of Physics", "publication": "Review of Scientific Instruments", "publication_date": "1938-01", "series_number": "1", "volume": "9", "issue": "1", "pages": "1-5" }, { "id": "authors:9vr5b-sy752", "collection": "authors", "collection_id": "9vr5b-sy752", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr37", "type": "article", "title": "Proton induced radioactivity in oxygen", "author": [ { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Barnes", "given_name": "S. W.", "clpid": "Barnes-S-W" }, { "family_name": "Buck", "given_name": "J. H.", "clpid": "Buck-J-H" } ], "abstract": "As previously reported(1,2) a large number of elements are found to become radioactive under bombardment by protons of energies up to 3.8 Mev. Two periods have been definitely established for oxygen, using targets of quartz and other solid oxides as well as a platinum foil in oxygen.", "doi": "10.1103/PhysRev.51.995", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1937-06-01", "series_number": "11", "volume": "51", "issue": "11", "pages": "995" }, { "id": "authors:b0xw8-8xk15", "collection": "authors", "collection_id": "b0xw8-8xk15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BARpr37", "type": "article", "title": "Proton-Induced Radioactivity in Heavy Nuclei", "author": [ { "family_name": "Barnes", "given_name": "S. W.", "clpid": "Barnes-S-W" }, { "family_name": "DuBridge", "given_name": "L. A.", "clpid": "DuBridge-L-A" }, { "family_name": "Wiig", "given_name": "E. O.", "clpid": "Wiig-E-O" }, { "family_name": "Buck", "given_name": "J. H.", "clpid": "Buck-J-H" }, { "family_name": "Strain", "given_name": "C. V.", "clpid": "Strain-C-V" } ], "abstract": "[No abstract.]", "doi": "10.1103/PhysRev.51.775.2", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1937-05-01", "series_number": "9", "volume": "51", "issue": "9", "pages": "775" }, { "id": "authors:8mvbp-6rc05", "collection": "authors", "collection_id": "8mvbp-6rc05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:MANpr37", "type": "article", "title": "The absolute photoelectric yields of Mg, Be and Na", "author": [ { "family_name": "Mann", "given_name": "Marvin M., Jr.", "clpid": "Mann-M-M-Jr" }, { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Measurements of the absolute photoelectric yields for distilled surfaces of Mg, Be and Na were made and values of \u03b1 in Fowler's photoelectric equation determined. For Mg, Be and Na the values of the work function are, respectively, 3.68, 3.92 and 2.29 volts and of \u03b1, 3.2, 25 and 180\u00d710^-34 cm^2 sec./quant. These values of \u03b1 range from 10^-2 to 10^-3 of the maximum theoretical values. The ratios are interpreted as the fraction of light absorbed by the electrons in the surface potential barrier.", "doi": "10.1103/PhysRev.51.120", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1937-01-15", "series_number": "2", "volume": "51", "issue": "2", "pages": "120-124" }, { "id": "authors:6p7mn-r1t13", "collection": "authors", "collection_id": "6p7mn-r1t13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr33b", "type": "article", "title": "The effect of temperature on the energy distribution of photoelectrons. I. Normal energies", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" }, { "family_name": "Hergenrother", "given_name": "R. C.", "clpid": "Hergenrother-R-C" } ], "abstract": "An experimental test has been made of DuBridge's theory of the distribution of normal energies of photoelectrons. With a modified parallel-plate method of analysis, photoelectrons were ejected from a strip of Mo foil which could be held at any desired temperature. Current-voltage curves for temperatures from 300\u00b0 to 965\u00b0K show a good agreement with the theory. From the shifts required to fit the experimental and theoretical curves the values of Vmax at 0\u00b0K can be determined. For any fixed temperature these values of Vm fit the Einstein equation, and for a fixed wave-length they are independent of T, as required by the theory.", "doi": "10.1103/PhysRev.44.861", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1933-12-01", "series_number": "11", "volume": "44", "issue": "11", "pages": "861-865" }, { "id": "authors:qq5ny-mjn59", "collection": "authors", "collection_id": "qq5ny-mjn59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBrsi33", "type": "article", "title": "An Improved d.c. Amplifying Circuit", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" }, { "family_name": "Brown", "given_name": "Hart", "clpid": "Brown-Hart" } ], "abstract": "The sensitivity of d.c. amplifying circuits with FP-54 tubes is limited by the stability which can be obtained. In single-tube circuits it is necessary to balance out fluctuations caused by changes in battery e.m.f. and in filament emission. Soller's circuit for balancing out e.m.f. changes has been studied in detail and a modified circuit has been developed in which the adjustments are less critical and which allows balancing out of changes in filament emission also. The latter is accomplished by balancing the plate current against the current to the space-charge grid. Details of construction and manipulation of the new circuit are given, as well as data on its stability.", "doi": "10.1063/1.1748993", "issn": "0034-6748", "publisher": "American Institute of Physics", "publication": "Review of Scientific Instruments", "publication_date": "1933-10", "series_number": "10", "volume": "4", "issue": "10", "pages": "532-536" }, { "id": "authors:fbq59-9c144", "collection": "authors", "collection_id": "fbq59-9c144", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr33a", "type": "article", "title": "Theory of the energy distribution of photoelectrons", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Because of the thermal energies of the electrons in a metal there can be no sharply defined maximum emission energy of photoelectrons, as was once supposed. On the basis of the Sommerfeld theory and the Fermi-Dirac statistics, expressions are derived for the form of the energy distribution and current voltage curves in the vicinity of the apparent maximum energy. The method used is similar to that used by Fowler in computing the total emission current. In Part I the energies normal to the emitting surface are considered. At 0\u00b0K the theoretical current-voltage curve is a parabola tangent to the energy axis at Vmax, while for higher temperatures it approaches the axis asymptotically. In Part II the treatment is extended to the total energy of emission and in this case the current-voltage curve at 0\u00b0K is a parabola concave toward the voltage axis and cutting it at a large angle. At higher temperatures there is an asymptotic approach. Even at room temperature there is an uncertainty of several hundredths of a volt in Vmax, though the theory yields a method of determining the maximum energy which would be observed at 0\u00b0K. Both parts of the theory are found to be in agreement with new experiments on molybdenum. The bearing of the theory on the photoelectric determination of h is discussed.", "doi": "10.1103/PhysRev.43.727", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1933-05-01", "series_number": "9", "volume": "43", "issue": "9", "pages": "727-741" }, { "id": "authors:4hm49-ya342", "collection": "authors", "collection_id": "4hm49-ya342", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr32c", "type": "article", "title": "The thermionic and photoelectric work functions of molybdenum", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" }, { "family_name": "Roehr", "given_name": "W. W.", "clpid": "Roehr-W-W" } ], "abstract": "The photoelectric and thermionic emission from pure molybdenum was studied during a prolonged process of outgassing by heat treatment at temperatures up to 2100\u00b0K. In a sealed-off tube an equilibrium condition was reached which was not changed by further treatment extending up to 1600 hours. Photoelectric curves taken at room temperature and at 940\u00b0K and analyzed by Fowler's method yielded a true work function for the outgassed Mo of 4.15\u00b10.02 volts. Thermionic data for the same specimen also yielded a work function of 4.15 volts, and a value of the constant A close to the theoretical value of 60 amp./cm^2 deg.^2.", "doi": "10.1103/PhysRev.42.52", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1932-10-01", "series_number": "1", "volume": "42", "issue": "1", "pages": "52-57" }, { "id": "authors:e5878-gs665", "collection": "authors", "collection_id": "e5878-gs665", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr32a", "type": "article", "title": "Photoelectric and thermionic properties of palladium", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" }, { "family_name": "Roehr", "given_name": "W. W.", "clpid": "Roehr-W-W" } ], "abstract": "The photoelectric and thermionic properties of pure palladium were studied during an extended outgassing in high vacuum. The threshold, obtained by extrapolation of spectral sensitivity curves, shifted from below 2300A to above 3000A and then back to a final value of 2486A as outgassing progressed. In the final state the photocurrents excited by monochromatic light increase with temperature, the relative increase being greater for the longer wave-lengths. At the higher temperatures the spectral sensitivity curves approach the axis asymptotically. The results are shown to be in excellent agreement with Fowler's recent theory and his method of analysis yields the value 4.97\u00b10.01 volts for the true work function (2486A). The thermionic work function for the clean specimen was found to be 4.99\u00b10.04 volts, and the value of the constant A is very close to 60 amp./cm2 deg2.", "doi": "10.1103/PhysRev.39.99", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1932-01-01", "series_number": "1", "volume": "39", "issue": "1", "pages": "99-107" }, { "id": "authors:9nkkr-6z965", "collection": "authors", "collection_id": "9nkkr-6z965", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr32b", "type": "article", "title": "A further experimental test of Fowler's theory of photoelectric emission", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Fowler's theory of photoelectric emission is discussed from the viewpoint of the experimental physicist and several significant consequences of the theory in analyzing experimental data pointed out. A new graphical method of testing the theory is suggested. This method makes it possible to determine the \"true\" photoelectric threshold of a surface from photocurrent-temperature curves taken at a single incident frequency, eliminating the necessity of measuring relative intensities of spectral lines. The method is applied to new experimental data on palladium and to Morris' data on gold and found to be completely successful, thus furnishing additional verification of Fowler's theory.", "doi": "10.1103/PhysRev.39.108", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1932-01-01", "series_number": "1", "volume": "39", "issue": "1", "pages": "108-118" }, { "id": "authors:0kkkf-d0379", "collection": "authors", "collection_id": "0kkkf-d0379", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr31", "type": "article", "title": "The amplification of small direct currents", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "A new type of thermionic tube recently described by Metcalf and Thompson has made it possible for the first time to construct d.c. amplifying circuits with a current sensitivity exceeding that of any form of electrometer except the Hoffman; and with a ruggedness and dependability unattainable with any form of sensitive electrometer. The circuits are easily constructed and simple to operate. Three types of circuits have been tested out and are described. (1) A simple single-tube circuit with a Type R galvanometer has been found satisfactory for measurements of currents as small as 10^-14 amp. (2) A two-tube bridge circuit gives greater stability and will easily measure currents of 10^-16 amp. It has been found capable of detecting currents of 5\u00d710^-18 amp. (3) A two-stage circuit, using one of the new tubes and one of the UX-112A type, will amplify currents of 10^-14 amp to such a value that they may be read on a microammeter.", "doi": "10.1103/PhysRev.37.392", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1931-02-15", "series_number": "4", "volume": "37", "issue": "4", "pages": "392-400" }, { "id": "authors:m6zp4-ft288", "collection": "authors", "collection_id": "m6zp4-ft288", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr28b", "type": "article", "title": "The thermionic emission from clean platinum", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "The thermionic emission from thoroughly outgassed platinum in high vacuum has been measured to one-half percent over the temperature range 1360 to 1750\u00b0K, the temperatures being measured by careful optical pyrometry. The values obtained for the thermionic constants of the T2 law are, when corrected for the Schottky effect, b=72, 820\u00b0K, \u03c6=6.27 volts, A=17,000 amp/cm^2 deg^2. The value of \u03c6 is possibly in error by not more than 1 percent because of uncertainties in the temperature scale, and agrees within one-half percent with the value of the photoelectric work function previously obtained. The data confirm the previous announcement that for clean platinum A is 250 times greater than the theoretical value of 60.2 amp/cm^2 deg^2.", "doi": "10.1103/PhysRev.32.961", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1928-12-01", "series_number": "6", "volume": "32", "issue": "6", "pages": "961-966" }, { "id": "authors:9fn54-6c918", "collection": "authors", "collection_id": "9fn54-6c918", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpnas28", "type": "article", "title": "Systematic variations of the constant A in thermionic emission", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Recent measurements(1) on the thermionic emission from a platinum surface during outgassing have brought to the attention of the writer an empirical relation between the thermionic constants for a metallic surface which was discovered by Richardson(2) for tungsten and platinum in 1915, but which has apparently been completely neglected in formulating the various theories of the emission process.", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "1928-10-01", "series_number": "10", "volume": "14", "issue": "10", "pages": "788-793" }, { "id": "authors:589ey-5es22", "collection": "authors", "collection_id": "589ey-5es22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr28a", "type": "article", "title": "The photoelectric and thermionic work functions of outgassed platinum", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "In extending results previously reported the photoelectric and thermionic work functions for platinum were studied while the specimen was put through an extended outgassing process. With monochromatic light the final value of the photoelectric threshold was found to be 1962A (6.30 v.) The thermionic work function increases during outgassing, reaching a final value of 6.35 volts, within 1 percent. The two work functions are thus in agreement within the limits of error. The thermionic constant A of the Richardson T^2 law also increases as the work function increases, reaching a final value which is 200 times or more greater than Dushman's theoretical value of 60.2 amp/cm^2 deg^2.", "doi": "10.1103/PhysRev.31.236", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1928-02-01", "series_number": "2", "volume": "31", "issue": "2", "pages": "236-243" }, { "id": "authors:rvyvs-ca431", "collection": "authors", "collection_id": "rvyvs-ca431", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr27", "type": "article", "title": "The photoelectric properties of thoroughly outgassed platinum", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Effect of heat treatment on the photo-currents from Pt. \u2014 The total photoelectric emission from a strip of Pt foil excited by the full radiation from a quartz mercury arc was studied while the strip was put through an extended heat treatment in pressures as low as 10^-8 mm Hg as read on an ionization gauge. Prolonged heating at 1200\u00b0-1400\u00b0C caused the photo-current to decrease to a final value which could not be further reduced by additional heating for as long as 300 hours at temperatures up to the melting point. The photo-current was found to increase spontaneously from the low values observed immediately after a heating interval to much higher values if the strip was allowed to remain at room temperature for a short time. After thorough outgassing of the strip and the tube however this \"recovery\" effect finally disappeared. \n\nEffect of heat treatment on the long wave-length limit of Pt. \u2014 The long wave-length limit was determined by using filters of dilute acetic acid in a fluorite cell to cut out the shorter Hg lines. The threshold was found to shift during outgassing from above 2500A to a final steady value of 1958\u00b115A. This is at variance with Suhrmann's value of 2675A but is shown to be in agreement with the work of Tucker and Woodruff. Pressure readings taken with an ionization gauge of high sensitivity confirm the conclusions (a) that decreasing photo-currents are caused by the evolution of absorbed gases, (b) that increasing photo-currents (recovery effect) are due to the adsorption of gas by the cool Pt surface, and (c) that the final low values of the photoemission are characteristic of the gas-free Pt. Heating an outgassed strip in air at 0.015 mm pressure caused the photo-currents to disappear; heating in hydrogen at the same pressure caused them to increase. They were brought back to values characteristic of the completely outgassed state in each case by heating for 30 sec. at a pressure of 10^-6 mm. \n\nInfluence of temperature on the photo-emission from Pt. \u2014 The photoelectric effect of Pt is found to be independent of the temperature only in the region below 500\u00b0C. At higher temperatures up to 1200\u00b0C the photocurrents increase considerably with temperature and the threshold shifts slightly to the red. Several explanations of the effect were tested and are discussed, the conclusion being that it is a genuine temperature effect characteristic of the metal itself and due to the increase in the thermal energies of the \"free\" electrons which may become appreciable at the higher temperatures.", "doi": "10.1103/PhysRev.29.451", "issn": "0031-899X", "publisher": "Physical Review", "publication": "Physical Review", "publication_date": "1927-03-01", "series_number": "3", "volume": "29", "issue": "3", "pages": "451-465" }, { "id": "authors:7z000-vm084", "collection": "authors", "collection_id": "7z000-vm084", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpnas26", "type": "article", "title": "Variations in the photo-electric sensitivity of platinum", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "The photo-electric properties of a platinum surface which has undergone an extended process of outgassing by heat treatment have been studied by many recent observers and conflicting results have been reported.", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "1926-03-15", "series_number": "3", "volume": "12", "issue": "3", "pages": "162-168" }, { "id": "authors:7qy3h-r0r83", "collection": "authors", "collection_id": "7qy3h-r0r83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:DUBpr25", "type": "article", "title": "Positive rays produced by ultra-violet light", "author": [ { "family_name": "DuBridge", "given_name": "Lee A.", "clpid": "DuBridge-L-A" } ], "abstract": "Experimental test for positive photo-electric emission from Au, Cu and Al. \u2014 Following the announcement by Dember in 1909 that positive emission had been observed, an attempt was made to verify its existence under improved conditions. His experiment was repeated using light from a quartz mercury arc and curves similar to his obtained. It was found, however, that when proper precautions against scattered light effects were taken, no true positive current could be detected from Au, Cu, or Al surfaces, and it is shown that the Dember effect may be accounted for on the basis of spurious currents due to scattered light. Outgassing of the surface failed to cause the appearance of any positive current.", "doi": "10.1103/PhysRev.25.201", "issn": "0031-899X", "publisher": "American Physical Society", "publication": "Physical Review", "publication_date": "1925-02", "series_number": "2", "volume": "25", "issue": "2", "pages": "201-207" } ]