Direct Calculation of Two-Photon Absorption Transition Intensities of Pr 3+ in Cs 2 NaPrCl 6

Mohamed Bouazaoui, B. Jacquier, C. Linarès +2 more

F. Arqueros, Paul E. LaRocque, Maurice S. O'Sullivan +1 more

Absorption ratios of doublets arising from n(2)D(5/2,3/2)? n'(2)S transitions in Rb (n = 5-9, n' = 5) and Cs (n = 7-13, n' = 6) were measured by Doppler-free two-photon spectroscopy using a thermionic ion detector. The observed ratios agree with calculated values for transitions to the higher levels but differ significantly for levels n = 5 in Rb and n =7, 8 in Cs. These experiments also provide new lower bounds for the ionization potentials of Rb(2) (3.62 eV) and Cs(2) (3.682 eV).

Dianyuan Wang, Lixin Ning, Shangda Xia +1 more

Eighteen selected two-photon absorption (TPA) transition line strengths with polarization angles θ = 0° and 45°, spanning several orders of magnitude, have been calculated for the Tb 3+ ion in the cubic host Cs 2 NaTbCl 6 . The results are in reasonable agreement with experimental results in the literature. The calculation utilized the crystal field (CF) wavefunctions for the initial and final states of the 4f 8 configuration, and utilized free ion or CF wavefunctions (with the corresponding energies) for 4f 7 core states of the whole intermediate 4f 7 5d configuration comprising 34 320 states. The intensities of certain transitions were found to be very sensitive to the inclusion of the CF interaction within the 4f 7 core. In contrast to previous fourth- or third-order calculations of the TPA transition line strength of the strong transition ( 7 F 6 )A 1g → ( 5 D 4 )A 1g using pure Russell–Saunders (RS) wavefunctions for the | 7 F 6 ⟩ initial and ⟨ 5 D 4 | final states, our second-order direct calculation shows that the admixed RS wavefunctions |[ 7 F 6 ]⟩ and ⟨[ 5 D 4 ]| must be used to account for its high intensity. The effects of CF interactions within the 4f 7 core, i.e. J -mixing and CF energy level splitting, upon the ( 7 F 6 )A 1g → ( 5 D 4 )E g TPA transition line strength have been separated, and the latter effect is shown to be more important for the transition investigated.

Bowen Xie, Swapan Kumar Gayen

Bin Qing Xie, Y. M. Cheung, Swapan Kumar Gayen

Michael Caracas Núñez, Miguel A. Gonzalez, Mayerlin Núñez Portela

The probability of a two-photon absorption (TPA) process is quantified by means of the TPA cross-section. In this work the TPA cross-section for the 6 S 1/2 → 8 S 1/2 transition in cesium (Cs) atoms is obtained from a theoretical and experimental approach. It is calculated using second order perturbation theory including hyperfine structure and Doppler broadening for a thermal atomic vapor. The theoretical values for the TPA cross-sections of the two allowed hyperfine transitions are σ ~ 3,3 =3.10×10 −24 cm 4 /W and σ ~ 4,4 =3.65×10 −24 cm 4 /W. An experiment is set up to measure these cross-sections based on the quadratic dependence between the TPA transition rate and the intensity of the laser light. Values of σ ~ 3,3 =(3.6±1.1)×10 −24 cm 4 /W and σ ~ 4,4 =(4.6±1.1)×10 −24 cm 4 /W are obtained from the measurements. The results show an agreement between theory and experiment. To the best of our knowledge, this is the first time that these cross-sections are reported.