Thulium ion

The MCI2 (M = Ca, Sr, and Ba) crystals are ideal candidates for studies of the spectroscopic properties of Tm " ions. First, no charge-compensation defects are required after thulium ions are introduced into these hosts. Second, there is reliable experimental information about the absorption/emission spectra of these materials [2-8]. Moreover, the earth-alkaline halides are also important from an application point of view because the laser action has been achieved in CaF2 Tm [9]. The spectra of Tm " were modeled in our earlier publication [10]. 

As seen from table 10, parameters of coupling with deformations in the basis plane of lattice differ insignificantly for diluted and concentrated crystals, however this difference is unambiguously registered in experiments. Parameters for thulium ions in the... 

The strong anisotropy of the spin-lattice relaxation at near parallel orientations of an applied field Ifo, which follows from eq. (186) (the factor sin 0 ), has been observed in TmES (fig. 18) (Aminov et al. 1984). An increase of the relaxation rate at a 0-change from 90° to 7.5° may be due only to the increase of the correlation time tc- As mentioned above, the dependence Tc(0), is due to the broadening of the doublet level of thulium ion by interionic interactions. 

Other exponential contributions to the relaxation rates of Ce +, Nd " " ions are explained naturally from the same standpoint. It seems reasonable to associate the contributions Tj (X exp(-A /kBT) with 4 = 18-19cm with an influence of the thulium ions of the first coordination sphere on the impurity lanthanide ions. An impurity ion distorts the crystal field at a distance of 3.7 A so strongly, that the thulium doublet state is split by approximately 20cm . In fact, there already appears a purely singlet Stark structure of energy levels in the low-symmetry crystal field. The distinction of 4 values for different lanthanide ions ean easily be coimected with the distinction of differences between the ionic radii of impurities and the ionic radius of the host thulium ion. The difference is... 

Fig.6.68. Two examples of IR absorption spectra, (cr. carbon monoxide gas [6.120], b thulium ions in a crystalline matrix [6.121])...

The incorporation of metallic NPs in RE-doped glasses has been intensively investigated in recent years for its positive effects on the PL behaviors of RE ions. Among various RE ions, the trivalent thulium ion exhibits rich emissions from visible bands to the mid-lR region, and its absorption band for the H4 state at 0.8 pm facilitates the use of the commercial GaAlAs diode laser as a pump source. In the present work, the NIR PL spectra of the Tm -doped 70GeS2-... 

Similar to other rare-earths, thulium has a single oxidation state of +3. A general formula for the positive ion of thulium and the elements found in group 7 (fluorides) with a negative ion is expressed as follows ... 

Holmium is obtained from monazite, bastnasite and other rare-earth minerals as a by-product during recovery of dysprosium, thulium and other rare-earth metals. The recovery steps in production of all lanthanide elements are very similar. These involve breaking up ores by treatment with hot concentrated sulfuric acid or by caustic fusion separation of rare-earths by ion-exchange processes conversion to halide salts and reduction of the hahde(s) to metal (See Dysprosium, Gadolinium and Erbium). 

In 1955 the next step was announced. Very intense helium ion bombardment of tiny targets of E253 produced a few spontaneously fissionable atoms which eluted from ion-exchange resins in the eka-thulium position. This was evidence that element 101 had been found. Only seventeen atoms of this element were produced. It showed a half-life of between one-half and several hours. The name mendelevium (symbol... 

Johnson et al. (55) observed energy transfer from erbium to thulium and from erbium to holmium ions in crystals. They were able to obtain substantial decreases in laser thresholds because of this energy migration. The fluorescent lifetime of the 3//4 state of thulium in CaMo04 containing 0.75 atomic per cent erbium and 0.5 atomic per cent thulium as inferred from the time delay before the onset of laser oscillation is 900 /xsec at both IT and 20°K. 

Oxyhalides. The oxyhalides of yttrium, lanthanum, and gadolinium are good host lattices for activation with other rare-earth ions such as terbium, cerium, and thulium. The use of LaOCl Tb3+ as the green component in projection-television tubes has been discussed [5.419]. LaOBr Tb3+ and LaOBr Tm3+ exhibit high X-ray absorption, and they are used in X-ray intensifying screens [5.420]. 

Thulium occurs in apatite and xenotime and is derived from these minerals as a minor coproduct in the processing of yttrium. Processing involves organic ion-exchange, liquid-liquid, or solid-liquid, techniques. Prior to the development of cation exchange resins capable of separating the chemically similar rare earths, thulium was practically unavailable in... 

Although rare-earth ions are mosdy trivalent, lanthanides can exist in the divalent or tetravalent state when the electronic configuration is dose to the stable empty, half-filled, or completely filled shells. Thus samarium, europium, thulium, and ytterbium can exist as divalent cations in certain environments. On the other hand, tetravalent cerium, praseodymium, and terbium are found, even as oxides where trivalent and tetravalent states often coexist. The stabilization of the different valence states for particular rare earths is sometimes used for separation from the other trivalent lanthanides. The chemicals properties of the di- and tetravalent ions are significantly different. 

Oxalic acid is a precipitation agent for rare earth ions. The solubility of rare earth oxalates range from 10 to lO" mol in neutral solutions. The precipitate usually contains coordinated and/or lattice water molecules, RE2(C204)3 n H2O, where = 10 for lanthanum to erbium and yttrium while n = 6 for holmium, erbium, thulium, ytterbium to lutetium and scandium. 

The thulium (III) ion exhibits spectrally narrow light emission at about 480 nm. Li and coworkers were the first to use the Tm + ion in OLEDs [65]. They prepared a Tm complex Tm(acac)3(phen) and constructed double-layer cells with structure ITO/PVK/Tm complex/Al. The electroluminescence spectrum of the OLED with drive voltage 10 V and the photoluminescence spectrum with excitation wavelength at 350 nm are shown in Figure 11.29. The emitting intensity of 6.0cdm was achieved when a 16 V forward bias voltage was applied. 

Compounds of divalent samarium, europium, and ytterbium are well-known. In recent years, lower halides of other lanthanides, such as neodymium 48), praseodymium 45, 49, 90), and thulium 4) have been obtained by reducing the trihalide with the metal. The corresponding reaction of thorium tetraiodide with thorium metal has led to the identification of two crystalline forms of Thl2 41, 91) it is unlikely that the Th ", or even Th ", ion is present in Thl2, but like Prl2, which is formulated as Pr " (r)2( ) (2), the compound is probably of the type Th " (r)2(2 ) 41). Certainly one crystal form is diamagnetic 41), suggesting the latter formulation. 

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