Relative cross sections for calcium(1F3) sublevels (| M | = 0-3) through alignment effects in collisional energy transfer: calcium(4s4f,1F3) + rare gas .fwdarw. calcium(4p2,1S0) + rare gas as a function of rare gas

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Velocity dependent statetostate differential cross sections for rotational transfer in Li2-Xe using velocity selected double resonance Individual cross sections for 1 D 2 sublevels (M L =0, ±1, ±2) in the alignmentdependent process: Ca(4p 2 1 D 2)+Rg→Ca(3d4p 1 F 3)+Rg as a function of rare gas J. Chem. Phys. 92, 5260 (1990); 10.1063/1.458532Statetostate integral cross sections for the inelastic scattering of CH(X 2Π)+He: Rotational rainbow and orbital alignment J. Chem. Phys. 91, 821 (1989); 10.1063/1.457134The anisotropic interaction potential of D2Ne from statetostate differential cross sections for rotational excitationThe initial state alignment effect vs relative velocity is measured for a state-to-state Ca Rydberg collisional energy transfer process. The stimulated emission detection method is used to determine the alignment effect for the n,l-changing transition: Ca(4s17d 1 D 2 )ϩXe→Ca(4s18p 1 P 1 ) ϩXeϩ⌬EϭϪ1.7 cm Ϫ1 . The rate of electronic energy transfer in this state-changing collision is observed to vary with the direction of the Rydberg electron charge cloud relative to the collision axis. Both the expected cos͑4␤͒ and cos͑2␤͒ dependencies are observed. The alignment data are analyzed to obtain the relative cross sections for the individual Ca͑ 1 D 2 ͒ magnetic sublevels. The values of the m-sublevel cross sections 0 : ͉1͉ : ͉2͉ are 1.13Ϯ0.02:1.11Ϯ0.02:0.83Ϯ0.02. Qualitative interpretations of the relative cross sections in terms of both molecular ͑van der Waals͒ Born-Oppenheimer potentials and the impulse approximation are presented.

Section: A Overviewmentioning

confidence: 99%

Orbital alignment cross sections by stimulated emission probing: The state-to-state Ca Rydberg process Ca(4s17d 1D2)+Xe→Ca(4s18p 1P1)+Xe

Spain

Dalberth

Kleiber

et al. 1995

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In condensed phases, for example, time-resolved fluorescence polarization anisotropy provides information regarding the reorientational dynamics of the resonant electronic transition dipoles of the excited chromophores. The analysis of such fluorescence depolarization experiments can determine rates of rotational diffusion, energy transfer, and energy relaxation, as well as indicate orientational motion restrictions in large molecular systems.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10] In the gas phase, resonance fluorescence polarization studies address issues of collision dynamics and intramolecular energy redistribution. [11][12][13][14][15][16][17][18][19][20] The angular distribution and polarization of resonance fluorescence is used, in particular, to determine the resulting orientation and alignment of an initially anisotropic distribution of atomic or molecular collision partners. [13][14][15][16][17][18][19] For an initially isotropic distribution of free rotor transition dipoles, molecular rotation will cause a depolarization of the resonance fluorescence as the photoselected population precesses around the spatial and molecular fixed frames axes.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16][17][18][19][20] The angular distribution and polarization of resonance fluorescence is used, in particular, to determine the resulting orientation and alignment of an initially anisotropic distribution of atomic or molecular collision partners. [13][14][15][16][17][18][19] For an initially isotropic distribution of free rotor transition dipoles, molecular rotation will cause a depolarization of the resonance fluorescence as the photoselected population precesses around the spatial and molecular fixed frames axes. In addition, collisions with the bath or solvent are anticipated to also randomize molecular orientations prepared in the initial photoselection step and hence further increase the depolarization of the reradiated resonance emission.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The resonance fluorescence polarization of free rotors: Methyl iodide in methane and carbon dioxide

Ziegler

Fan

1996

Energy migration and rotational motion within bichromophoric molecules. II. A derivation of the fluorescence anisotropyAn instantaneous normal mode analysis of solvation: Methyl iodide in high pressure gasesThe polarization of the resonance fluorescence of symmetric top rigid rotors is described by a third-order density matrix treatment of resonance emission and a sum-over-all-rovibronic states scattering-tensor invariant framework. Within this theoretical approach the resonance fluorescence depolarization is a function of the excited electronic state population and rovibronic coherence decay rates, as well as the electronic absorption/emission line shapes. This description of the depolarization of resonance fluorescence is contrasted with that of resonance Raman in terms of angular momentum selection rules and dependence on material relaxation parameters. In contrast to resonance Raman emission in solution, the accompanying resonance fluorescence polarization is found to be most sensitive to the resonant excited state lifetime when this population decay time is of the order or less than rotational periods. These effects are demonstrated for excitation resonant with the B-state origin of CH 3 I vapor in high pressures of CH 4 and CO 2 . The solute-solvent interaction responsible for the pure dephasing of the resonant optical coherence does not appear to cause orientational redistribution of the excited chromophore, at least on the time scale of the CH 3 I B-state origin lifetime. The influence of excited electronic B-state rovibrational pure-dephasing effects on the resonance fluorescence polarization measurements are discussed.

“…Such insight has been gleaned from energy transfer processes of initially aligned valence orbitals. Two-, three-, and four-vector correlations of aligned atomic valence states have been examined experimentally [10][11][12][13][14][15][16][17] and theoretically. 18 -26 Recently, we are extending the studies of alignment effects to include statechanging collisions of Rydberg atoms.…”

Section: Introductionmentioning

confidence: 99%

Alignment probing of Rydberg states by stimulated emission

Spain

Dalberth

Kleiber

et al. 1995

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The possibility of probing the collisions of aligned Rydberg atoms by stimulated emission is assessed with studies of a polarized state and a new measurement of a collisional alignment effect in atomic Ca. The stimulated emission method uses a laser to dump the desired state to a lower level which subsequently fluoresces. The technique can be used to obtain populations and polarization dependent information. First, the method is tested by applying it to an aligned Ca(4s17d 1 D 2 ) state. Alignment curves are measured when the initial state is prepared with both parallel and perpendicular relative polarizations. The experimentally observed alignment compares well with that derived from theoretical considerations of a saturated stimulated transition. Second, a two-vector collisional alignment experiment ͑initial state and relative velocity vector͒ is performed to study the energy transfer process Ca(4s7d, and alignment effects are measured by both stimulated emission and conventional direct fluorescence detection. A preference for the ͉m͉ϭ1 and 2 initial states is observed in the relative cross sections. Essentially identical data are obtained with the two detection methods when elliptically polarized light is used for the stimulated emission detection method. The stimulated emission technique can provide alignment and population information of the final states, making it an excellent new tool for both three-vector correlation experiments and state-to-state Rydberg transitions.