POLARIZATION DEPENDENCE OF 2-PHOTON EXCITATION-SPECTRA IN THE S-8(7 2)-]P-6(7/2), P-6(5/2), AND P-6(3/2) TRANSITION REGIONS OF GD3+ IN (C4H4O5)(3)]CENTER-DOT-2NACLO(4)CENTER-DOT-6H(2)O/
Ke. Gunde et al., POLARIZATION DEPENDENCE OF 2-PHOTON EXCITATION-SPECTRA IN THE S-8(7 2)-]P-6(7/2), P-6(5/2), AND P-6(3/2) TRANSITION REGIONS OF GD3+ IN (C4H4O5)(3)]CENTER-DOT-2NACLO(4)CENTER-DOT-6H(2)O/, Journal of luminescence, 69(5-6), 1996, pp. 355-368
The relative intensities and polarization properties of two-photon abs
orption (TPA) transitions are examined throughout the S-8(7/2) --> P-6
(7/2), P-6(5/2), and P-6(3/2) excitation regions of Gd3+(4f(7)) in sin
gle crystals of Na-3[Gd(oda)(3)] . 2NaClO(4) . 6H(2)O (where oda denot
es an oxydiacetate ligand of chemical formula C4H4O52- = (OOCCH2OCH2CO
O-)-O--). In these crystals the Gd3+ ions are located at sites of D-3
point symmetry, and the Gd(oda)(3)(3-) coordination complexes have chi
ral, tris-terdentate chelate structures. These crystals exhibit natura
l optical activity, and they differentially absorb left- and right-cir
cularly polarized light in both one-photon and two-photon excitations
of the Gd3+ 4f --> 4f (intraconfigurational) electronic transitions. I
n the present study, results are reported for fluorescence-detected TP
A measurements performed under three different excitation polarization
conditions: left-circularly polarized, right-circularly polarized, an
d linearly polarized. In each case, excitation was with a single beam
of laser radiation directed along the unique axis of a uniaxial single
-crystal sample. The results include relative intensities and polariza
tion properties determined for transitions to each of the nine Stark l
evels split out of the P-6(7/2), P-6(5/2), and P-6(3/2) multiplets of
Gd3+ (4f(7)). Experimental measurements are analyzed in terms of a mod
ified Judd-Pooler perturbation model that explicitly incorporates spin
-dependent interaction terms. Calculated versus experimentally determi
ned ratios of circularly polarized to linearly polarized transition in
tensities are used as a diagnostic of the efficacy of the various calc
ulational methods in rationalizing the experimental results. The calcu
lations show some modest success in reproducing many of the qualitativ
e features of the experimental results, but they fail to account for m
any of the quantitative details.