Judd-Ofelt Parameters

Kumar et al., 2005). In turn the Judd-Ofelt parameters were calculated and the radiative lifetime estimated from eqs. (14)—(18). It is noteworthy that Judd-Ofelt parameters reproduce the observed spectra well. Photophysical data are listed in table 19 along with the emission cross section and the lifetime of the Er(4Ii3/2) level. The emission spectra were obtained by exci-... 

Extensive research including the study of radiative and non-radiative properties of rare-earth ions has been carried out. Especially, the Judd-Ofelt theory has been applied to most rare-earth — fluoride-glass combinations. Typical Judd-Ofelt parameters are reported in Table 3 for ZBLAN glass [31-34], An exhaustive list of such parameters for glasses and crystals can be found in Ref. [35]. 

In most cases, the Judd-Ofelt parameters are calculated with good confidence considering that results from various laboratories are convergent. They are found to adequately predict the radiative properties — lifetimes and branching ratios — of several transitions especially for Ho3+, Er3+, and Tm3+ ions in ZBLAN as well as in fluoroindate glasses. 

Judd-Ofelt parameters Q, (r = 2, 4, 6) of rare-earth ions in ZBLAN fluoride glasses... 

Gd3+ ion possesses high energy levels located in the UV. Absorption spectra of Gd3+-doped fluoride glasses show several peaks in the 240-320 nm range. They correspond to transitions from the 8S7/2 ground state to the 6P, 6I, and 6D excited states. Judd-Ofelt parameters and experimental lifetimes have been determined for Gd3+-doped fluorozirconate [34,141], and fluoroindate glasses [142], X-ray excitation of both glasses leads to radiative emission from all excited states 6P, 6I,... 

Judd-Ofelt parameters are listed in the tables for each lanthanide in each host when they are available in the literature. In most cases, they are determined by fitting absorption intensities. As is the case with crystal-field parameters, we simply list the H, and we do not attempt to give any details on the manner in which the parameters were derived and their accuracy. In each host, we refer the interested reader to the published literature for further details. 

Nd ions were present in the glass, with the former being predominant. The Judd-Ofelt parameters were also obtained, spontaneous emission cross sections were determined (ff 2.95 X 10" cm for the emission at 1049 cm ) similar to... 

Judd-Ofelt parameter Q2> Nd( F3/2) lifetimes and quantum yields of various fluorinated tris(jS-diketonates). 

Many of the transitions in the range of near 900 nm to the ground manifold %/2 possess laser emission, while some of them have cross-sections of >10 cm at room temperature. The Judd-Ofelt parameters have been used to calculate the branching ratios Ptj of the emission transitions due to the excited manifold. Por emission of " P3/2, the quality factor X = is particularly important. Por very... 

Table 11 Judd-Ofelt parameters for Ln aqua ions in dilute acidic solution [8] Ln...

Table 12 Judd-Ofelt parameters for Nd in selected environments [11,48]...

An attractive feature of the Judd-Ofelt approach is that once the intensity parameters are determined, they can be used to calculate the probability of transitions between any 4f" levels of interest for laser action. This includes absorption and fluorescence intensities, excited-state absorption, radiative lifetimes and branching ratios, and, combined with fluorescence spectra, stimulated emission cross sections (Krupke, 1974a). Best results are obtained for the lower-lying levels of 4f" which are well separated from the opposite-parity configurations and thus in keeping with the approximations made by Judd and Ofelt. Since the Judd-Ofelt parameters are not expected to differ greatly for adjacent ions in the lanthanide series, estimates can be made using extrapolated n values. 

The complexes of bidentate P-diketonates, where the hypersensitive transitions were discovered (Moeller and Ulrich, 1956) have been further studied (Kirby and Palmer, 1981 Richardson, 1982a). The Judd-Ofelt parameters and the luminescence of Eu(III) and Tb(III) [replacing caldum(II) with comparable ionic radius] have been informative about many biological materials (Horrocks and Sudwick, 1981 Richardson, 1982b) and absorption spectra of neodymium(III) complexes of multidentate amino-acids (Bukietynska and Mondry, 1985). 

References to early uses of Judd-Ofelt parameters to predict radiative lifetimes from a higher to a lower excited /-level in materials with established i, values are summarized by Reisfeld (1975) and by Reisfeld and J0rgensen (1977). The main use of such results is to predict the branching ratio for the... 

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