The Discoverers of the Platinum Isotopes
The Discoverers of the Platinum Isotopes
The Discovery of the Thirty Seven known Platinum Isotopes between 1935 and 1996
The history of the discovery of the isotopes of platinum, made over some 61 years between 1935 and 1996, can be gleaned from the various editions of the monograph “Table of Isotopes” (1–8). However, except for a few cases, in general, little attempt has been made to correlate the circumstances of the discoveries of the isotopes of individual elements. In this article attention is drawn to the work of pioneering scientists who in a comparatively short period of creativity discovered the majority of the isotopes of platinum.
There are thirty-seven known isotopes of platinum and six of these occur naturally with the authorised isotopic abundances stated below (9).
|Mass number||Isotopic abundance, %|
Of these, the five major isotopes were discovered by Dempster at the University of Chicago, Illinois, in 1935 using a new type of mass spectrograph; however, he only identified the mass numbers (10). The actual isotopic abundances were measured using the same technique by Sampson and Bleakney in 1936 (11), although earlier in the same year Jaeckel and Kopfermann (12) and Kopfermann and Krebs (13) had obtained reasonable estimates of the relative isotopic ratios of the four major isotopes (the last four) by a study of the hyperfine structure of the neutral platinum spectra. An earlier attempt by Venkatesachar and Sibaiya to use this technique for platinum led to a misidentification of the mass numbers of the major isotopes (14).
The rare isotope, 190Pt, was identified by Duckworth, Black and Woodcock (15) at the Wesleyan University, Middletown, Connecticut, in 1949 using the mass spectrographic technique and was shown to be radioactive by Porschén and Riezler in 1954 (16). The half-life of 190Pt is currently accepted as 6.5 × 10” years (650 Gy) (17).
Artificial Platinum Isotopes
In 1935, the possible existence of radioactive platinum isotopes was inferred by McLennan, Grimmett and Read (18) at the Radium Institute, London, and also by Amaldi and colleagues (19) in the Physics Laboratory at the University of Rome by slow neutron bombardment of the metal. However, the mass numbers could only be guessed at until later in the same year when Dempster identified the major naturally occurring isotopes using his new type of mass spectrograph.
The first definite identification of a radioactive platinum isotope was probably in 1936 by Cork and Lawrence (20) in the Department of Physics of the University of California who produced an isotope with a half-life of 14.5 hours. They used chemical means to identify the isotope as platinum and assigned it to the ‘missing’ 197Pt.
A year later, McMillan, Kamen and Ruben (21) at the same Department of Physics produced an isotope which had a half-life of 18 hours. This was also chemically identified as platinum and assigned to 197Pt. Although both set of claims were initially tentative, the two teams of claimants have subsequently been credited with the discovery of this isotope in the “Table of Isotopes” (1–8).
The major period of discovery was, however, in the 1960s when sixteen new isotopes were announced. In 1966, the Finnish physicist, Antti Siivola, working at the Lawrence Radiation Laboratory, University of California, announced the production and identification of nine new isotopes of platinum (22). He also confirmed three others which had been discovered by Graeffe in 1963 at the University of Helsinki (23).
s is second, min is minute, h is hour, d is day, y is year
ms is millisecond (10−3 s), μs is microsecond (10−6 s), Gy is gigayear (109 y)
More recently work has been concentrated on discovering the light isotopes and although such isotopes have half-lives in the millisecond region they are all alpha emitters, so that for platinum the proton drip line (see Appendix) has not yet been crossed. The latest research to take place will be looking for the isotope 165Pt, which is likely to decay by alpha emission. This work is connected with experiments which are searching for the proton emitting isotope 164Ir.
The actual methods for the production and identification of the isotopes are given in the original reports and summarised in the Table of The Discoverers of the Platinum Isotopes.
|Notes to the Table|
|A||168Pt||Alpha energy only, the half-life was measured by Bingham et al . in 1996 (25).|
|B||171Pt||Alpha energy only, the half-life was measured by Della Negra et al . in 1981 (44) and Enge et al . in 1981 (45).|
|C||172Pt||Alpha energy only, the half-life was measured by Enge et al . in 1980 (45, 46).|
|D||173Pt||Alpha energy only, the half-life was measured by Cabot et al . in 1975 (27).|
|E||184Pt||The half-life, determined by Graeffe at 20 minutes, was confirmed by Siivola in 1966 (22). Other reported values are 2.6 hours by Malysheva et al . in 1960 (33) and 42 minutes by Qaim in 1964 (47).|
|F||186Pt||Smith and Hollander first characterised this isotope in 1955 but incorrectly assigned the mass number as 187 (35). This mistake was indirectly corrected by Scharff-Goldhaber et al . in 1957 (48) who reassigned the mass number of a daughter isotope from 187lr to 186lr.|
|G||190Pt||The radioactive nature of this naturally occurring isotope was discovered by Porschén and Riezler in 1954 (16).|
|H||193Pt||Naumann only determined the half-life to be less than 500 years. The accepted value was determined by Soy, Ravn and Bøgeholt in 1971 (49).|
|I||195mPt||Non-specified activities of 3.3 days by McMillan, Kamen and Ruben in 1937 (21) and 3.45 days by Hole in 1948 (50) were assigned to 195mPt by the “Table of Isotopes”.|
|J||197Pt||Although the claimed discovery by Cork and Lawrence was tentative (20), a later assignment by McMillan Kamen and Ruben in 1937 was equally tentative (21).|
|K||197mPt||Non-specified activities of 80 minutes by Sherr, Brainbridge and Anderson in 1941 (51), 78 minutes by Hole in 1948 (50) and 87 minutes by Mock et al . in 1948 (52) were assigned to 197mPt by the ‘Table of Isotopes”.|
|L||199Pt||Non-specified activities of 36 minutes by McLennan, Grimmett and Read (18) and 50 minutes by Arnaldi et al . (19), both in 1935, were assigned to 199Pt by the “Table of Isotopes”.|
In this Table the mass number of each isotope is listed together with the half-life as selected by the compilers of the NUBASE Data Base (17). However, the data for 170Pt comes from a more recent review (24). Isomeric states (indicated by the suffix “m”) are included if their half-lives exceed one millisecond or if they are a significant fraction of the half-life of the ground state, if the latter is also short. The principal decay modes are listed in order of abundance, with a question mark indicating that the decay type is either expected or has been detected but that the percentage abundance has not been measured.
The year of discovery of an isotope is generally taken to be the year in which the discovery was placed in the public domain and is therefore either a manuscript date or a conference report date. If the discovery was announced by different groups at the same time, but independently, then all are included in an order which makes use of the above dating system.
Criteria for Discovery
Most important are the criteria for the correct identifications of the atomic number and the mass number of isotopes, although the sequence of discovery is not considered to be complete until an important radiation property, such as the half-life, or in the case of alpha emitters, for example, the unique alpha energy spectrum, has been measured. In the ‘Notes to the Table’ if the alpha energy spectrum was found first, the first determination of the half-life is also included. For naturally-occurring isotopes, discovery is considered to be the first identification by mass spectrography.
J. J. Livingwood and G. T. Seaborg, Rev. Mod Phys ., 1940, 12, 30
G. T. Seaborg, Rev. Mod. Phys ., 1944, 16, 1
G. T. Seaborg and I. Perlman, Rev. Mod Phys ., 1948, 20, 585
J. M. Hollander,, I. Perlman and G. T. Seaborg, Rev. Mod. Phys ., 1953, 25, 469
D. Strominger,, J. M. Hollander and G. T. Seaborg, Rev. Mod. Phys ., 1958, 30, 585
C. M. Lederer,, J. M. Hollander and I. Perlman, “ Table of Isotopes ”, 6th Edn., John Wiley and Sons Inc ., New York, 1967
E. Browne,, J. M. Dairiki,, R. E. Doebler,, A. A. Shihab-Eldin,, L. J. Jardine,, J. K. Tuli, and A. B. Buyrn,, “ Table of Isotopes ”, 7th Edn., C. M. Lederer and V. S. Shirley (eds.), Wiley Interscience, John Wiley and Sons Inc ., New York, 1978
C. M. Baglin,, S. Y. F. Chu, and J. Zipkin,, “ Table of Isotopes ”, 8th Edn., R. B. Firestone and V. S. Shirley (eds.), Wiley Interscience, John Wiley and Sons Inc ., New York, 1996
Commission on Atomic Weights and Isotopic Abundances – Subcommittee for Isotopic Abundance Measurements, Pure Appl. Chem ., 1998, 70, 217
A. J. Dempster, Nature, 1935, 135, 993
M. B. Sampson and W. Bleakney, Phys. Rev ., 1936, 50, 732
B. Jaeckel and H. Kopfermann, Z. Phys ., 1936, 99, 492
H. Kopfermann and K. Krebs, Z. Phys ., 1936, 101, 193
B. Venkatesachar and L. Sibaiya, Nature, 1935, 136, 65 and Proc. Indian Acad. Sci ., 1935, 2, 101
H. E. Duckworth,, R. F. Black and R. F. Woodcock, Phys. Rev ., 1949, 75, 1438
W. Porschén and W. Riezler, Z. Naturforsch ., 1954, 9a, 701 and ibid ., 1956, 11a, 143
G. Audi,, U. Bersillon,, J. Blachot and A. H. Wapstra, Nucl. Phys ., 1997, A624, 1
J. L. McLennan,, L. G. Grimmett and J. Read, Nature, 1935, 135, 147
E. Amaldi,, O. D’Agostino,, E. Fermi,, B. Pontecorvo,, R. Rasetti and E. Segrè, Proc. R. Soc. Land, 1935, 149A, 522
J. M. Cork and E. O. Lawrence, Phys. Rev ., 1936, 49, 788
E. McMillan,, N. Kamen and S. Ruben, Phys. Rev ., 1937, 52, 375
A. Siivola, Nucl. Phys ., 1966, 84, 385
G. Graeffe, Ann. Acad. Sci. Venn. Ser. A VI, 1963, ( 128 ), 1
C. M. Baglin, Nucl. Data Sheets, 1999, 86, 449
C. R. Bingham,, K. S. Toth,, J. C. Batchelder,, D. J. Blumenthal,, L. T. Brown,, B. C. Busse,, L. F. Conticchio,, C. N. Davids,, T. Davinson,, D. J. Henderson,, R. J. Irvine,, D. Seweryniak, . W. B. Walters,, P. J. Woods and B. E. Zimmerman, Phys. Rev ., 1996, C54, R20
(a) S. Hofmann, G. Münzenberg, F. Hessberger, W. Reisdorf, P. Armbruster and B. Thuma, Z. Phys ., 1981, A299, 281 ; (b) S. Hofmann, G. Münzenberg, W. Faust,, F. Hessberger, W. Reisdorf, J. R. H. Schneider,, P. Armbruster, K. Güttner and B. Thuma, Proc. 4th Int. Conf. on Nuclei Far From Stability, L. O. Skolen, Helsingør, Denmark, 7th-13th June 1981, CERN, Geneva, Rep. 81–09, 1981, Vol. I, p. 190
C. Cabot,, C. Deprun,, H. Gauvin, B. Lagarde,, Y. LeBeyec and M. Lefort,, Unpublished work quoted by H. Gauvin, Y. LeBeyec, J. Livet and J. L. Reyss, Ann. Phys. (Paris), 1975, 9, 241
A. Visvanathan,, E. F. Zganjar,, J. L. Wood,, R. W. Fink,, L. L. Reidinger and F. E. Turner, Phys. Rev ., 1979, C19, 282
J. Burde,, R. M. Diamond and F. S. Stephens, Nucl. Phys ., 1966, 85, 481
G. Albouy,, M. Gusakow and N. Poffé, J. Phys. Radium, 1960, 21, 751
(a) M. Finger, R. Foucher, J. P. Husson, J. Jastrzebski, A. Johnson, C. Sébille,, R. Henck, J. M. Kuchly,, R. Regal, P. Siffert, G. Astner, R. R. Erdal, E. Hagebø,, A. Kjelberg, F. Münnich, P. Patzelt, E. Beck and H. Kugler,, Rep. 70–29, CERN, Geneva, 1970 ; (b) The ISOLDE Collaboration, R. R. Erdal, M. Finger, R. Foucher, J. P. Husson, J. Jastrzebski, A. Johnson, C. Sèbille,, R. Henck, R. Regal, P. Siffert, G. Astner, E. Beck, A. Kjelberg, F. Münnich and P. Patzelt, Proc. Int. Conf. on the Properties of Nuclei Far From the Region of Beta-Stability, Leysin, Switzerland, 31st Aug.-4th Sept., 1970, Rep. 70–30, Vol. 2, 1970, CERN, Geneva, p. 1045
V. I. Baranov,, K. Ya. Gromov,, B. S. Dzhelepov,, Zyong Chong Bai,, T. V. Malysheva,, V. A. Morozov,, B. A. Khotin and V. G. Chumin, Izv. Akad. Nauk SSSR Ser. Fiz ., 1960, 24, 1079 (Bull. Acad. Sci. USSR Phys. Ser ., 1960, 24, 1086 )
T. V. Malysheva,, B. A. Khotin,, A. K. Lavrukhina,, L. N. Kryukova and V. V. Murav’eva, Izv. Akad. Nauk SSSR Ser. Fiz ., 1960, 24, 1109 (Bull. Acad. Sci. USSR Phys. Ser ., 1960, 24, 1113 )
R. A. Naumann, Phys. Rev ., 1954, 96, 90
W. G. Smith and J. M. Hollander, Phys. Rev ., 1955, 98, 1258
G. Wilkinson, Phys. Rev ., 1948, 73, 252 and ibid ., 1949, 75, 1019
R. A. Naumann, Bull. Am. Phys. Soc., Ser. II, 1956, 1, 42
(a) O. Huber, F. Humbel,, H. Schneider and A. de Shalit, Helv. Phys. Acta, 1951, 24, 629 ; (b) A. de Shalit, O. Huber and H. Schneider, ibid ., 1952, 25, 279
D. Christian,, R. F. Mitchell and D. S. Martin, Phys. Rev ., 1952, 86, 946
M. A. Walgren and W. W. Meinke, Phys. Rev ., 1959, 115, 191
L. P. Roy,, J. C. Roy and J. S. Merritt, Phys. Rev ., 1957, 105, 1337
J. Facetti,, E. Trabal,, R. McClin and S. Torres, Phys. Rev ., 1962, 127, 1690
S. Shi,, W. D. Huang,, Y. Li,, D. Z. Yin,, J. H. Gu and J. Q. Tian, Z. Phys ., 1992, A342, 369
S. Della Negra,, C. Deprun,, D. Jacqet and Y. LeBeyec, Z. Phys ., 1981, A300, 251
H. A. Enge,, M. Salomaa,, A. Sperduto,, J. Ball,, W. Schier,, A. Graue and A. Graue, Phys. Rev ., 1982, C25, 1830
H. Enge,, A. Dirienzo,, J. Molitoris,, A. Sperduto,, M. Salomaa,, J. Chervanek,, J. Ball,, W. Schier and H. Wegner, Bull. Am. Phys. Soc, 1980, 25, 486
S. M. Qaim J. Inorg. Nucl. Chem ., 1965, 27, 759
G. Scharff-Goldhaber,, D. E. Alburger,, G. Harbottle, and M. McKeown,, Private Communication, November 1957, to R. M. Diamond and J. M. Hollander, Nucl. Phys ., 1958, 8, 143
T. Soy,, H. L. Ravn and P. Bøgeholt, Phys. Rev ., 1971, C4, 600
N. Hole, Arkiv. Mat. Astron. Fysik, 1948, 36A, ( 9 ), 1
R. Sherr,, K. T. Brainbridge and H. H. Anderson, Phys. Rev ., 1941, 60, 473
D. L. Mock,, R. C. Waddell,, L. W. Fagg and R. A. Tobin, Phys. Rev ., 1948, 74, 1536
John W. Arblaster is Chief Chemist at Rotech Laboratories. He is interested in the history of science and in the evaluation of the thermodynamic and crystallographic properties of the elements.