Neodymium ion

Neodymium and YAG Lasers. The principle of neodymium and YAG lasers is very similar to that of the ruby laser. Neodymium ions (Nd +) are used in place of Cr + and are often distributed in glass rather than in alumina. The light from the neodymium laser has a wavelength of 1060 nm (1.06 xm) it emits in the infrared region of the electromagnetic spectrum. Yttrium (Y) ions in alumina (A) compose a form of the naturally occurring garnet (G), hence the name, YAG laser. Like the ruby laser, the Nd and YAG lasers operate from three- and four-level excited-state processes. 

The term solid-state laser refers to lasers that use solids as their active medium. However, two kinds of materials are required a host crystal and an impurity dopant. The dopant is selected for its ability to form a population inversion. The Nd YAG laser, for example, uses a small number of neodymium ions as a dopant in the solid YAG (yttrium-aluminum-gar-net) crystal. Solid-state lasers are pumped with an outside source such as a flash lamp, arc lamp, or another laser. This energy is then absorbed by the dopant, raising the atoms to an excited state. Solid-state lasers are sought after because the active medium is relatively easy to handle and store. Also, because the wavelength they produce is within the transmission range of glass, they can be used with fiber optics. 

The addition of dopants is found to have beneficial effects. However, they are not restricted only to transition metals. The hydrogenation of acrylic acid can be promoted significantly by the addition of neodymium ions onto the palladium particles [142], The selective transformation of 3,4-dichloronitrobenzene to the corresponding aniline has been selected to test pre-prepared Pt hydrosols as heterogeneous catalyst precursors (see Figure 3.9) [143],... 

Teranishi, T., Nakata, K., Miyake, M., and Toshima, N., Promition effect of polymer-immobilized neodymium ions on catalytic activity of ultra fine palladium particles, Chem. Lett., 277, 1996. 

The chloride ion in this structure is not bound to the neodymium ion but is hydrogen bonded to four water oxygens and the nitrogen atom, which form a distorted tetragonal pyramid around the anion. 

O Connor and Hargreaves (115) have reported a fluorescent lifetime of 225 sec for neodymium in CeF3. In this host there is both nonradiative and radiative energy exchange from the lattice d bands to the neodymium ions. 

Many factors affect coordination numbers and coordination polyhedra. It was recognized during 1962-1975 that the chemistry of yttrium and lanthanides is dominated by large coordination numbers. Although the structure of Nd(Br0.3>3 9H2O had been determined as early as 1939 by Helmholtz [6] and shown that the central neodymium ion was bound to nine water molecules in a face-centred trigonal prismatic structure, the commonly held opinion was that the rare earth ions formed six-coordinate, octahedral complexes [7]. This notion was based on the known octahedral, six-coordination known at that time for the most... 

The neodymium laser is popular because it is a solid state laser. Trivalent neodymium ions are incorporated in a host crystal or glass, at about one atomic percent doping. In the solid state, high concentrations of ions are available as opposed to the gaseous state. Further the host crystal provides mechanical strength and chemical inertness. 

The trivalent neodymium ion is a good example of a four-level laser system. The trivalent Nd3+ system is illustrated in Fig. 12.12 in a schematic fashion. 

Another difference is that the 5/orbitals have a greater spatial extension relative to the Is and Ip orbitals than the 4/orbitals have relative to the 6s and 6p orbitals. The greater spatial extension of the 5/orbitals has been shown experimentally the esr spectrum of UF3 in a CaF2 lattice shows structure attributable to the interaction of fluorine nuclei with the electron spin of the U3+ ion. This implies a small overlap of 5/ orbitals with fluorine and constitutes an / covalent contribution to the ionic bonding. With the neodymium ion a similar effect is not observed. Because they occupy inner orbitals, the 4/ electrons in the lanthanides are not accessible for... 

Figure I. The activity of the free neodymium ion as a function of total neodymium concentration in aqueous nitrate solution...

Table II. Activities and Activity Coefficients of the Free Neodymium Ion in Neodymium Nitrate Aqueous Solutions...

The polyvalent neodymium ions are assumed to have a slight effect on the glass pH electrode measurements. It also should be mentioned that the pH electrode was calibrated before and during use with buffer solutions of 4.01 and 2.27 pH values. 

The neodymium ion concentration in the organic phase was measured by back-extraction with 6M nitric acid, removal of the neodymium by adsorption with the cation exchange resin, Dowex 50 x 8, and titration of the neodymium-free aqueous phase with NaOH using phenolphtalein... 

Dipicolinates (pyridine-2,6-dicarboxylates) have been investigated in some detail with structures determined for several tris complexes such as Na3[Nd(dipic)3]-15H20 and Na3[Yb(dipic)3]13H20, typical of the early and later lanthanides, respectively. The lanthanides have essentially tricapped trigonal prismatic coordination geometries, isostruc-tural along the lanthanide series they have been the subject of important solution NMR studies. Mono and bis complexes can also be synthesized the mono complex [Nd(dipic)(H20)4] CIO4 has a polymeric structure in which each picolinate is bound to three different (nine-coordinate) neodymium ions. 

Among these, ais the most common mode, as in thecomplex [(CH3)3NCi6H33]3Nd(N03)6 2-Nitrate groups take on modes a and c when coordinated to neodymium ions. However, in the compound [(C4H9)4N]3 Nd(N03)e the nitrate group only adopts mode a (Figure 1.27). 

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