Holmium spectra

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. 

Erbium produces a brilliant emerald-green thermoluminescence, as discussed in the previous Chapter. Like the mixed oxides containing holmium compared with H02O3, there is more fine-structure in the emission spectrum of Er20s than of the mixed oxides of erbium(III). A common feature is the sharp edge of... 

Soret and Delafontaine identified holmium in 1878 by examination of its spectrum. The following year, Cleve separated its oxide from Marignac s erbia, a mixture of erbium, holmium and thulium oxides. He named this element Holmium, after his native town Holmia (Stockholm). The metal was produced in 1934 by Klemm and Bommer. 

The wavelength scale of a UV/visible spectrophotometer is checked by determining the specified wavelength maxima of a 5% w/v solution of holmium perchlorate. Figure 4.6 shows the spectrum of holmium perchlorate, the tolerances for ealibration wavelengths specified by the BP are 241.15 1 nm, 287.15 1 nm and 361.5 1 nm. 

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

Spectral Studies. UV spectra were recorded in methanolic solution (40-60 ppm) on a Beckman Model 26 spectrophotometer matched quartz cells having a 1-cm path length were used. A holmium oxide spectrum was recorded prior to the analysis of the samples for QA purposes. 

Lanthanide bromides and iodides have found important applications in a completely different field. They are added as additives in high-pressure discharge lamps in the lighting industry to improve the arc stability and the colour quality. The latter is due to the contribution of the multiline spectrum of the doped rare earths which are added to the salt mixture. Lanthanide trihalides of dysprosium, holmium, thullium, gadolinium and lutetium are used frequently for this purpose (Hilpert and Niemann, 1997). 

This technique works particularly well if the cocaine is mixed with sugars, from which it can be easily separated by dissolution. Calibration standards are prepared, in methanol solution, at concentrations of 1.0, 0.5, 0.25, 0.125, 0.0625, 0.031 25 and 0.0156 mgml using serial dilutions. A UV spectrum of a holmium filter is first measured to confirm that the instrumental set-up is performing satisfactorily. 

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. 

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. 

For most routine purposes, a solution of holmium oxide in perchloric acid will provide a convenient method for routinely checking the calibration of the wavelength scale. Figure 11 shows a typical spectrum. The values are known to within 0.2 nm and are adequate for most solution work. If wavelengths in the region below 241 nm are needed, then either atomic line sources such as a vapour discharge lamp or other rare earth solutions may be used. 

In the NIR part of the spectrum, the best lanthanides are ytterbium, erbium and neodymium. Holmium has been less investigated, but shows an emission spectmm with a peak in the red and a peak in the IR. 

FIGURE 35 ADXD spectrum of holmium at 137 GPa. The hkl assignment is done assuming the low symmetry structure to be C2lm (Vohra et al., 2008). 

ADXD spectrum, 296-297 crystal structure, 293-295 EDXD spectrum, 299/ 300/ 301/ phase transition, 293-295 volume-pressure data, 302/ holmium... 

Figure 3 Absorption spectrum produced by holmium oxide in perchloric acid solution, provided as a sealed cell certified reference material. Measured at the sample position, in a high performance reference commercial spectrophotometer, with air as the reference.

Figure 2 Absorption spectrum produced by a holmium glass certified reference material measured at the sample position in a high-performance reference commercial spectrophotometer. The singlet peak at 360 nm and the triplet centered at 450nmare particularly characteristic of this material.

It is unquestionable that dysprosium was discovered (1886) by de Boisbaudran alone. Having prepared sufficiently pure holmium , the scientist thoroughly studied its spectrum and discovered two new lines which pointed to the presence of an unknown element. After multiple recrystallizations he separated the impurity thus, dysprosium was discovered, as well as holmium. Its name originates from the Greek for difficult to obtain . The name is symbolic since it is characteristic of the REEs history. 

A great aihancement was observed by Bleaney et al. (1990) for Ho NMR spectrum in holmium nicotinate. The optical absorption spectrum of this compound shows that the lowest level of the Ho " ion is a singlet, with two other singlets at 8.1 and 15 cm". At 4.2 K the value of the paramagnetic shift a varies from 352 to 76 in the plane of reflection symmetry. 

The temperature dependence of the Gd + spin Hamiltonian parameters in PrV04 and of the resonance line width was investigated by Mehran et al. (1980) and Andronenko et al. (1981). A measurement of the Tm + ion spectrum in the VV paramagnet HoND (holmium nicotinate dihydrate) should also be noted (Baker et al. 1986b). The EPR in TbND has shown a spectrum from a relatively rare species of a paramagnetic ion (defect sites) in an undiluted compound of the same paramagnetic ion (Baker et al. 1987). 

Fig. 95. Properties of holmium ethylsulphate. (a) The magnetic field dependence of the thermal resistivity, (b) Dependence of the energy levels on magnetic field, (c, d, e) Schemes of contributions of different parts of the phonon spectrum to c, (maxima of curves are near hm T).

Figure 4-2. Spectrum of Holmium glass filter type 2, no. 720540 (Philips Pye Unicam) (slit 0.2 nm scan speed 0.5 nm s data interval 0.2 nm response 10 s). 

In the NIR side, the best lanthanides are 5dterbium, erbium, and neodymium (it is used in the Nd YAG laser, see Section 3.1.5). Holmium is less investigated but shows a very interesting emission spectrum with a red peak and an NIR peak. 

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