Trivalent lanthanides, energy levels

In what follows we briefly review some of the previous attempts to analyze the available spectra of plutonium (6). In addition, we estimate energy level parameters that identify at least the gross features characteristic of the spectra of plutonium in various valence states in the lower energy range where in most cases, several isolated absorption bands can be discerned. The method used was based on our interpretation of trivalent actinide and lanthanide spectra, and the generalized model referred to earlier in the discussion of free-ion spectra. 

Figure 6.1 An energy-level diagram for trivalent lanthanide rare earth ions in lanthanum chloride (after Dieke, 1968).

Carnall, W. T. Fields, P. R. Rajnak, K. Electronic energy levels of the trivalent lanthanide aquo ions. I-IV. J. Chem. Phys. 1968, 49(10), 4424-4455. 

Camall, W.T., Crosswhite, H., Crosswhite, H.M., 1997. Energy Level Stmcture and Transition Probabilities of the Trivalent Lanthanides in LaF3. Argonne National Laboratory, Argonne, USA. 

Electronic Energy Levels of the Trivalent Lanthanide Aquo Ions. II. Gd3+, W.T. Camall, P.R. Fields, andK. Rajnak. J. Chem. Phys. 49, 4443-4446 (1968). 

Fignre 9 shows the energy level diagrams of trivalent lanthanide ions in LaFs. Since the crystal field is a minor perturbation, the sequence of most levels does not depend on the host. 

Figure 10 Energy difference between the lowest levels of the 4f and 4f 5d configurations for divalent and trivalent lanthanide ions in fluorite. (Reproduced by permission of Ref. 37)...

Electronic configurations and spectral terms of ground state trivalent lanthanide ions are listed in Table 1.2. Figure 1.6 shows the energy level diagram for trivalent lanthanide ions. 

Figure 1.6 The energy level diagram for trivalent lanthanide ions [7]. (With kind permission from Springer Science+Business Media Lasers and Excited States of Rare Earths, 1977, p. 93, R. Reisfeld, and C.K. Jorgensen, figure 2, Springer-Verlag, Berlin.)...

Facile ligand modification To improve the chemical and physical properties of the emitting materials, such as suitability for vapor phase deposition, solubility, stability or carrier transporting properties, modification of the ligands is necessary. Since the 4f shells of trivalent lanthanide ions are well shielded by the filled 5s and 5p orbitals, the 4f energy levels are only weakly perturbed by the environment outside of the lanthanide ions. Thus, the modification does not result in much shift in the emission wavelength. 

W. T. Carnall, H. Crosswithe and H. M. Crosswithe, Energy Level Structure and Transition Probabilities of the Trivalent Lanthanide in LaFs, Argonne National Laboratory. Argonne, Iffinos, 4493 (1977). 

The absorption and emission spectra of the rare earths ions are well known (29). Recently Camall et al. (30) have given an extended review on the spectra and the calculation of the energy levels of the trivalent lanthanide ions in LaFs. 

We have calculated sets of theoretical energy levels for the trivalent actinides and lanthanides and correlated these levels with transitions observed in the solution absorption spectra of these elements. Using the eigenvectors resulting from this energy level calculation, we have computed the theoretical matrix elements required to account for the observed band intensities in the two series of elements. The extent to which the theoretical calculations can be correlated with experimental results has been discussed, and some applications for the intensity relationships are pointed out. 

Most published work on the energy levels in the trivalent lanthanides and actinides has been carried out in crystalline media, where the identity of a level in terms of a given coupling scheme can be experimentally established 8, 19). In attempting similar correlations in aqueous solution, one must rely heavily on the level identifications established in crystals. Where crystal data is not available, extrapolation of parameters... 

The values of F2 for the trivalent lanthanides and actinides are plotted vs. Z (atomic number) in Figure 7, and those of f are shown graphically in Figure 8. Values of F2 and 5/ for actinides above curium were extrapolated from the light half of the series assuming a linear relationship for the parameters (9). These parameters, in turn, were used to calculate the expected energy levels for Es ", and Fm-" ". ... 

Table I. Parameters Used to Calculate Energy Levels Observed in the Solution Absorption Spectra of the Trivalent Actinides and Lanthanides...

Fig. 3. Energy levels of eleven trivalent lanthanides below 43000 era-. The quantum number J is given to the right of each level, whereas the multiplicity (2S + 1) and L-value are only given to the left for such levels, where Russell-Saunders coupling is a good approximation. The black triangles give the levels most frequently found to fluoresce. The squares indicate levels to which transitions from the groundstate have pronounced pseudoquadrupolar hypersensitive character, and hence intensity in certain materials. The stippled lines indicate calculated positions of J-levels not yet identified. The diagram is taken from Ref.231...

Fig. 5. The probability of energy transfer from the uranyl ion to five trivalent lanthanides in phosphate glass as a function of the energy difference between the long-lived uranyl state and the closest J-level below...

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