Energy-Pooling Processes in Laser-Excited Alkali Vapors : An Update on Experiments

Allegrini, M.; Gabbanini, C.; Moi, L.

doi:10.1051/jphyscol:1985106

Cited by 17 publications

(4 citation statements)

References 5 publications

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“…Our observations and theory should be relevant to a variety of other physical situations such as quasiresonant collisional interactions in dense atomic vapors [9][10][11] or avalanche upconversion systems. 12 A useful objective of additional observations of bistability in such systems would be improved understanding of the time dependence of the phenomenon.…”

Section: Introductionmentioning

confidence: 94%

Cooperative optical bistability in the dimer system Cs3Y2Br9:10% Yb3+

Hehlen

Güdel

Shu

et al. 1996

The Journal of Chemical Physics

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In single crystals of the dimer compound Cs 3 Y 2 Br 9 :10% Yb 3ϩ below 31 K, both visible ͑VIS͒ and near-infrared ͑NIR͒ luminescence intensities were found to exhibit hysteresis as a function of incident NIR intensity and temperature. The optical bistability is intrinsic to Cs 3 Y 2 Br 9 :10% Yb 3ϩ and not a result of an external feedback. Lowering the temperature to 11 K strongly enhances the all-optical switching behavior. The switching on VIS cooperative upconversion and NIR luminescence transitions occurs simultaneously and with opposite polarity reflecting the competition of both emission processes. On/Off switching ratios of up to 4.8 and 1.7 were observed for VIS and NIR luminescence intensities. Using NIR luminescence spectroscopy, differences in the internal sample temperature of up to 7 K were found between the upper and lower branches of the hystereses. A two-level density-matrix model is developed which includes ground-and excited-state interactions and shows that the intrinsic bistability due to a local field different from the external field is strongly amplified by the nonlinear cooperative upconversion process. Alternatively, a rate-equation model is presented which takes the multilevel nature of the ions into account but is more phenomenological in nature. Formally, the two models are shown to be equivalent, and they qualitatively explain all major experimental observations. It is found both theoretically and experimentally that increasing the coupling within Yb 3ϩ dimers and/or decreasing energy migration through the Yb 3ϩ lattice enhances switching and renders it easier to observe intrinsic optical bistability.

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Section: Introductionmentioning

confidence: 94%

Cooperative optical bistability in the dimer system Cs3Y2Br9:10% Yb3+

Hehlen

Güdel

Shu

et al. 1996

The Journal of Chemical Physics

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“…therein). Associative ionization at thermal energies (see again [3]) and photoassociative ionization in low temperature traps [5,6] have also been observed. Cascade emission, amplified spontaneous emission, parametric four-wave generation and stimulated electronic Raman scattering take place when exciting the 4p 2 P level [7][8][9][10].…”

Section: Introductionmentioning

confidence: 90%

“…The branching ratio between Cd(5p 3 P 0 ) and Cd(5p 3 P 2 ) for process (3) has not been determined directly, but one can assume that the 5p 3 P 0 channel dominates, by virtue of its smaller energy defect (∆E = −542 cm −1 ); in fact, the cross section is substantially independent of temperature [21,22], which would not be the case for the 5p 3 P 2 endothermic channel (∆E = 1171 cm −1 ). At equilibrium, with a typical heat pipe temperature of 730 K, the 5p 3 P 0 , 5p 3 P 1 and 5p 3 P 2 population ratios would be 1 : 1.03 : 0.17.…”

Section: Andmentioning

confidence: 99%

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Theoretical study of Na(4p2P) + Na(3s2S) and Cd(5p3P0) + Na(3s2S) collisions and their role in the energy transfer between Cd.* and Na

Magnier

Angeli

Granucci

et al. 1997

Z Phys D - Atoms, Molecules and Clusters

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We have computed the cross sections for the energy transfer process Cd(5p 3 P 0 ) + Na(3s 2 S) → Cd(5s 1 S) + Na(4p 2 P) and for the state changing collision Na(4p 2 P) + Na(3s 2 S) → Na(3d 2 D) + Na(3s 2 S), based on theoretical interaction potentials for the NaCd and Na 2 systems, respectively. Our calculations shed light on the interpretation of experiments with laser excited Na+Cd vapour mixtures [1]. It turns out that Cd(5p 3 P 0 ), in rapid equilibrium with the doorway state Cd(5p 3 P 1 ), efficiently transfers energy to Na, populating the 4p 2 P state. The collisions with ground state Na cause a very fast conversion of the 4p 2 P to the 3d 2 D state, from which the strongest emission is observed.

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Energy-pooling reactions

Bicchi

1997

Rivista Nuovo Cimento

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Energy-Pooling Processes in Laser-Excited Alkali Vapors : An Update on Experiments

Cited by 17 publications

References 5 publications

Cooperative optical bistability in the dimer system Cs3Y2Br9:10% Yb3+

Cooperative optical bistability in the dimer system Cs3Y2Br9:10% Yb3+

Theoretical study of Na(4p2P) + Na(3s2S) and Cd(5p3P0) + Na(3s2S) collisions and their role in the energy transfer between Cd.* and Na

Energy-pooling reactions

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