Molybdenum deuteron bombardment

Nuclide chart showing stable molybdenum isotopes and radioactive products from deuteron bombardments... 

Gr. technetos, artificial) Element 43 was predicted on the basis of the periodic table, and was erroneously reported as having been discovered in 1925, at which time it was named masurium. The element was actually discovered by Perrier and Segre in Italy in 1937. It was found in a sample of molybdenum, which was bombarded by deuterons in the Berkeley cyclotron, and which E. Eawrence sent to these investigators. Technetium was the first element to be produced artificially. Since its discovery, searches for the element in terrestrial material have been made. Finally in 1962, technetium-99 was isolated and identified in African pitchblende (a uranium rich ore) in extremely minute quantities as a spontaneous fission product of uranium-238 by B.T. Kenna and P.K. Kuroda. If it does exist, the concentration must be very small. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars. 

The Noddacks also claimed to have detected element 43 and named it masurium after Masuren in Prussia. This claim proved to be incorrect, however, and the element was actually detected in 1937 in Italy by C. Perrier and E. Segre in a sample of molybdenum which had been bombarded with deuterons in the cyclotron of E. O. Lawrence in California. It was present in the form of the emitters Tc and Tc... 

Ernest 0. Lawrence (1901-1958) bombarded molybdenum with cyclotron-accelerated deuterons element 43 could be proved in this experiment. Only radioactive isotopes exist. 

Technetium was the first element, not found on Earth, to be artificially produced by bombarding molybdenum with deuterons. 

Existence of technetium was predicted from the vacant position in the Periodic Table between manganese and rhenium. Noddack, Tacke, and Berg reported its discovery in 1925 and named it masurium. The metal actually was never isolated from any source by these workers. Its existence, therefore, could not be confirmed. Perrier and Segre in 1937 produced this element by bombarding molybdenum metal with deuterons in a cyclotron. They named the element technetium derived from the Greek word technetos, meaning artificial. 

C. Perrier and E. G. Segre discover technetium (element 43) among the fission products of molybdenum which has been bombarded with deuterons in the Berkeley cyclotron. 

The first element ever to be produced artificially is that of atomic number 43. In 1937, Perrier and Segre isolated minute amounts of a radioactive isotope of this element from a sample of molybdenum that had been bombarded with deuterons in a cyclotron. This element was given the name technetium (Tc), which is derived from the Greek word meaning artificial. The bulk of the evidence now available indicates that this element does not occur in nature. Although several isotopes of... 

Technetium does not occur terrestrially, but has been observed in the spectra of the sun and certain stars. Perrier and Segre (1937) made the 90-day JTc by bombarding molybdenum with high-energy deuterons from a cyclotron. The isotope more useful as a tracer is the 60-day 43TC. The long-lived J Tc is obtained (Motta, Boyd and Larsen, 1947) by long irradiation of molybdenum in an atomic pile ... 

We had very good reason to think that molybdenum bombarded by deuterons would make element 43, which we now call technetium. Molybdenum has 42 protons in its nucleus. A deuteron, the nucleus of a deuterium or heavy hydrogen atom, has 1 proton and 1 neutron. Technetium, of course, has 43 protons in its nucleus. 

Technetium is an artificial element obtained by the radioactive decay of molybdenum. Element 43, named technetium in 1947, had been discovered in 1937 by Carlo Perrier and Emilio Segre in a sample obtained from the Berkely Radiation Laboratory (now Lawrence Berkeley National Laboratory) in California (Perrier and Segre 1937, 1947). By bombarding a molybdenum strip with 8-MeV deuterons in a 37-in. cyclotron, a radioactive molybdenum species (half-life, 65 h) had been obtained which decayed by yff-emission to a short-lived isotope (half-life, 6 h) with novel properties, identified as technetium-99m (Segre and Seaborg 1938). 

The discovery of technetium in 1937 by the Italian scientists Carlo Perrier and Emilio Segre was an important affirmation of the configuration of the Periodic Table. The table had predicted the existence of an element with 43 protons in its nucleus, but no such element had ever been found. (In fact, technetium does not occur naturally on Earth, as all of its known isotopes are radioactive and decay to other elements on a timescale that is relatively small when compared with the age of the earth.) Perrier and Segre were able to observe technetium from molybdenum that had been bombarded with deuterons. They named the element technetium, from the Greek word technetos, meaning artificial. Technetium is produced in relatively large quantities during nuclear fission, so there is currently an ample supply of the element from nuclear reactors and nuclear weapons production. 

In 1937 a molybdenum target that had been bombarded for many months with deuterons in a cyclotron showed radio-activity... 

Nor was it merely artificial isotopes that were formed. Artificial elements were formed also. In 1937, Lawrence, the inventor of the cyclotron, had bombarded a sample of molybdenum (atomic number 42) with deuterons (nuclei of hydrogen-2). He sent the bombarded sample to Segr6 in Rome. (Later Segre was to come to the United States and in his new home was to discover the anti-proton.)... 

Berkeley cyclotron for several months prior to shipping the plate to Segre s group in Italy in late December, 1936. Perrier and Segre began their radiochemical studies in late January, more than 6 weeks after the end of bombardment. On the surface exposed to the deuterons, they found strong activity, chiefly due to very slow electrons ascribed to more than one substance of a half-value period of some months in addition to (which they could not explain, but did not attribute to reactions with molybdenum). 

All the artificial elements are, of course, radioactive, and the first to be prepared was technetium. It was produced in vanishingly small quantity in 1939 by Segre and Perrier by bombarding element 42 (molybdenum) with deuterons for several months. It was also detected the following year among uranium fission products. A few years later, the same source yielded promethium, the missing rare earth element. 

In 1937 Perrier and Segre bombarded a molybdenum target with deuterons to produce technetium as the first man-made element [34]. This element has 31 known isotopes with mass numbers firom 86 to 117, and all are radioactive. The most readily available isotope is Tc = 2.1 X10 years), which can be isolated from spent nuclear fuel where it constitutes approximately 6% of the fission product yield of U. In the recovery process, the pertechnetate anion, [ TcO, ] , is extracted with pyridine firom aqueous solution and ultimately isolated as [NH j [TcO, ] with a purity of better than 99.9% [35]. The ammonium salt is readily available at a reasonable cost from Oak Ridge National Laboratory [36]. 

---