Absorption holmium

L. Holmia, for Stockholm). The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after cleve s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. 

Holmium (Ho, [Xe]4/n6s2), name and symbol after the Latin word for the city of Stockolm, Holmia. Discovered (1879) by P.T. Cleve even though the holmium absorption spectrum was observed the year before by the Swiss chemists J.L. Soret and M. Delafontaine. 

Figure 8.1 Theoretically calculated f and f" values as a function of wavelength in the vicinity of the K absorption edge of selenium (a) and the L edge of holmium (b).

Cleve s fame rests chiefly, however, on his discoveries among the rare earths. After obtaining some erbia from which all the ytterbia and scandia had been removed, and after noticing that the atomic weight of the erbium was not constant, he succeeded in resolving the earth into three constituents erbia, holmia, and thulia (21). The absorption bands of holmium had already been noticed by the Swiss chemists M. Delafontaine... 

Figure 10.3. (c) Absorption spectrum of holmium oxide filter. 

There are many ways to check the wavelength accuracy of a UV-Vis detector. For detectors with built-in wavelength verification, the deuterium line at 656 nm or the absorption bands at 360, 418, 453, and 536 nm in a holmium oxide filter... 

J. C. Travis et al., Intrinsic Wavelength Standard Absorption Bands in Holmium Oxide Solution for UV/Visible Molecular Absorption Spectrophotometry, J. Phys. Chem. Ref. Data 2005,34, 41. 

Four rare-earth elements (yttrium, ytterbium, erbium, and terbium) have been named in honor of this village. A year later, the Swedish chemist Lars Fredrik Nilson (1840-1899), discovered another element in "erbia" and he named it scandium (Sc) in honor of Scandinavia. At the same time, Nilson s compatriot, the geologist and chemist Per Theodor Cleve (1840-1905) succeeded in resolving the "erbia" earths yet another step further, when he separated it into three components erbium, "holmium" (Flo) and thulium (Tm). The name "holmium" refers to Stockholm (Qeve s native city) and had been independently discovered by the Swiss chemists Marc Dela-fontame (1838-1911) and Jacques-Louis Soret (1827-1890), who had coined the metal element X on the basis of its absorption spectrum. 

Figure 10.3. (d) Absorption specti um of holmium oxide solution. 

Electronic absorption spectra were recorded on a Perkin-Elmer 575 instrument calibrated with holmium oxide. The absorption spectra of native pigments, sodium borohydride reduction... 

Yttrium is one of the most abundant rare earth elements and its purification is easily accomplished. Yttrium fractions from a bromate series are freed from dysprosium, holmium, and erbium by fractional precipitation with ammonia, K2OO4, or NaNC>2. The latter is probably the most effective. Yttrium salts give no absorption lines ini the viable portion of the spectrum, consequently the removal of holmium and erbium is easily observed by the direct vision spectroscope. 

Absorption spectra of the MB-loaded zeolites are taken in the range 300 - 800 nm. The spectrometer (PE Lambda 9) is equipped with a diffuse reflectance attachment. Sodium zeolites are generally used as diluent or reference standard. Holmium oxide is used for the calibration of slight drifts in the recording stabiiity of the instrument, thus, enabling quantitative photometric evaluations of reflectance spectra. 

The lutetium hahdes (except the fluoride), together with the nitrates, perchlorates, and acetates, are soluble in water. The hydroxide oxide, carbonate, oxalate, and phosphate compotmds are insoluble. Lutetium compounds are all colorless in the solid state and in solution. Due to its closed electronic configuration (4f " ), lutetium has no absorption bands and does not emit radiation. For these reasons it does not have any magnetic or optical importance, see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Neodymium Praseodymium Promethium Samarium Terbium Ytterbium. 

Several new isocyanide complexes of chromium(m) have been prepared by the electrochemical reduction of heavy-metal adducts of chromium(iii) aquocyano-complexes, and characterized by their visible spectra. The chromium 2p- and 3s-orbital ionization potentials in K3[Cr(NCS)6] have been reported, and the lattice parameters for this anion in the salt with diaquotris-(nicotinic acid)holmium(iii) determined. " The absorption spectra of the... 

In-line optical transmittance spectra of the Zr02-doped Ho Y203 ceramics sintered at 1800 °C for 30 h, which were from the powders corresponding to different slurry concentrations, are shown in Fig. 3.24. All the absorption peaks are related to holmium ion (Ho " ) absorption in the Y2O3 matrix. With decreasing slurry... 

For detectors with built-in holmium oxide filter we recommend in principle to use this filter. However, the determination of the UV absorption maxima of holmium oxide requires a good optical resolution (better than 2nm). Many HPLC detectors are built with a fixed slit of 8-10 nm bandwidth which is inadequate for this task. In case of doubt it is best to ask the manufacturer or to use anthracene. 

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