Neodymium discovery

Spectrum of the Glowing Oxide.—Neodymium oxide is one of the very few solids with a discontinuous spectrum. The spectrum which was known long before neodymium was separated from its fellow element praesodymium, was briefly described by Bunsen1 in 1864, who in the same communication mentions the discovery by Bahr2 of the similarly banded spectrum of erbium oxide. Thus far, however, no thorough-going study seems to have been made of this class of spectrum. 

Numerous binary and ternary diene polymerization initiator systems with neodymium as the rare-earth metal component have been designed empirically and investigated since the early discoveries in the 1960s. Commercially used neodymium-based catalysts mostly comprise Nd(III) carboxylates, aluminum alkyl halides, and aluminum alkyls or aluminum alkyl hydrides [43, 48,50-52]. Typically, the carboxylic acids, which are provided as mixtures of isomers from petrochemical plants carry solubilizing aliphatic substituents R. They are treated with the alkylaluminum reagents to generate the active catalysts in situ (Scheme 11). 

Mendeleev s Periodic Table made no provision for a lanthanide series. No one could predict how many of these elements would exist and it was not until Moseley s work on X-ray spectra that resulted in the concept of atomic number (1913) that it was known that an element with atomic number 61, situated between neodymium and samarium, remained to be discovered. Although several claims were made for its discovery in lanthanide ores, it was realized that no stable isotopes of element 61 existed and, from the late 1930s, nuclear chemistry was applied to its synthesis. 

Auer von Welsbach was another chemist who doubted the validity of fhe American results. Finally, the married couple, Ida Noddack (nee Tacke, 1896-1978) and Walter Noddack (1893-1960), embarked upon a quest for fhe element 61. Husband and wife were greatly stimulated by their recent discoveries of masurium and rhenium. The Noddacks, in collaboration with Berg, began their investigations with an enormous amount of rare-earfh minerals (Noddack ef al., 1925). They firsf of all produced a number of very pure samples of neodymium and samarium. They made use of the most sensitive and accurate methods of analysis of fhat time, allowing to detect element 61 if if were 10 million times more rare than neodymium and samarium. However, their work remained without success. 

Due to these recent discoveries, chemists did not lose their faith and they still hoped to discover the element 61 in nature. But most of them realized that it would probably be more successful to synthesize the element artificially. Technetium, the first artificially prepared element, had been formed in 1937 in the Berkeley cyclotron (Perrier and Segre, 1937,1947). One year later, in July 1938, the American physicists Pool and Quill of the University of Ohio started bombarding a neodymium target with fast deuterons (Pool and Quill, 1938). They were hoping that the proton would be taken up by the neodymium nuclei, with the formation of element 61 as a consequence ... 

If attention is now turned to the heavier elanents as shown in the model, it is seen that the five unknown elements eka-caesimn, e -manganese 1, eka-mmiganese 2 (dwi-manganese), eka-iodine, and eka-neodymium, have odd atomic numbers. (There is some doubt as to the discovery of thulium 2.) Not only are the unknown elements odd numbered, but among the radio-active elements, if the most stable isot( of each element is used for the comparison, the odd numbered elemente are much less stable than the adjacent elements of even number. 

The man who made this discovery was Auer. He selected these two names because they mean new twin (neodymium) and green twin (praseodymium). The elements were called twins because they were both so much like lanthanum. 

Promethium. Pm at. wt of best known isotope 147 at. no. 61 valence 3. All known isotopes are radioactive mass numbers 140-154. M7Pm, a 0-emitter, T, 2.62 years. The discovery of element 61 in rare earth concentrate was claimed by Harris and Hopkins, J, Am. Chem. Soc. 48, 1585 (1926) and by Rolla and Fernandez, Gazz. Chim. ItaL 56, 435 (1926). Evidence of existence in nature is inconclusive Yost et ah. The Rare Earth Elements and Their Compounds (John Wiley, New York, 1947). First obtained synthetically by irradiating neodymium and praseodymium with neutrons, deuterons, and alpha particles Law et at., Phys. Rev. 59, 936 (1941). Positive identification by inn-exchange chromatography Marinsky et ah, J. Am. Chem. Soc. 69,... 

The method evolved by Moseley (1887 to 1915) of determining the atomic number enabled chemists to ascertain, as has already been seen, the maximum number of elements that can exist in serial order between any two selected ones. As the atomic numbers of lanthanum and lutecium are 57 and 71, it is clear that it is possible for 13 elements to exist of atomic numbers between these. Now europium was the twelfth to be discovered, but no element corresponding to 61 had been recorded. This should lie between neodymium (60) and samarium (62), and as early as 1902 Bohuslav Brauner had predicted its existence. In 1926 Hopkins, of Illinois, with his collaborators Harris and Yntema, announced the discovery of a new element in the neodymium extracted from monazite sand, the lines of the X-ray spectrum agreeing with those expected for element 61. He called it Illinium. 

With the discovery of the laser, it has been possible to irradiate materials with intense monochromatic light. Brish et al. [86] were the first to show that an intense infrared beam (X= 1060 nm) of light from a neodymium-glass laser could initiate lead azide. A point to be noted is that the wavelength of the light beam is far from the absorption edge of lead azide [2]. The Q-switched beam was 15 mm diam, was unfocused, and had a duration of 0.1 /isec. Lead azide of... 

Discovery Carl Gustaf Mosander in Stockholm discovered didymium, the twin , in 1840. Carl Auer von Welsbach in Vienna discovered in 1885 that didymium is composed of two elements. One of them he called praseodymium the green twin , the other neodymium the new twin . 

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