Two-photon absorption of a circularly polarized UV beam of a femtosecond laser at 256 nm is used to pump ground state electrons of Xe-136 to the m = +2 or m = -2 sublevels of the 6p [5/2]2 excited state depending on the handedness of the circular polarization. A copropagating circularly polarized IR beam of a CW laser at 788.134 nm is used to further excite these electrons to the 8s [3/2]2 state through a single photon absorption process. The absorption of the IR beam is measured by a fast detector. In theory, the same and the opposite handedness of the circular polarization of the two beams respectively result in a forbidden and an allowed final transition, hence zero and finite absorption of IR photons, respectively. In practice, finite absorption is observed in both cases. However, the absorption signal in the forbidden case is less intense and delayed by about 70 ps relative to the absorption in the allowed case. This time delay is a measure of the depolarization rate at which exited electrons in m = +/-2 sublevels move to other sublevels, namely, m = +/-1 and m = 0 making the final transition possible, resulting in the delayed absorption of IR photons.Two-photon absorption of a circularly polarized UV beam of a femtosecond laser at 256 nm is used to pump ground state electrons of Xe-136 to the m = +2 or m = -2 sublevels of the 6p [5/2]2 excited state depending on the handedness of the circular polarization. A copropagating circularly polarized IR beam of a CW laser at 788.134 nm is used to further excite these electrons to the 8s [3/2]2 state through a single photon absorption process. The absorption of the IR beam is measured by a fast detector. In theory, the same and the opposite handedness of the circular polarization of the two beams respectively result in a forbidden and an allowed final transition, hence zero and finite absorption of IR photons, respectively. In practice, finite absorption is observed in both cases. However, the absorption signal in the forbidden case is less intense and delayed by about 70 ps relative to the absorption in the allowed case. This time delay is a measure of the depolarization rate at which exited electrons in m = +/-2 sublevels move to other sublevels, namely, m = +/-1 and m = 0 making the final transition possible, resulting in the delayed absorption of IR photons.

AIAA AVIATION ForumJul 16, 20251 citation

Polarization states of the two-photon system

Vanik E. Mkrtchian, V. O. Chaltykyan

Optics CommunicationsAug 1, 198714 citations

Polarization and intensity spectra for Mg-Ne and Mg-Ar fractional collisions

D. A. Olsgaard, Rosemary A. Lasell, Mark D. Havey +1 more

Extensive experimental studies of Mg-Ne and Mg-Ar fractional collisions are reported. In the fractional-collision process, two-color, two-photon absorption takes place during a single binary collision. Polarization and relative intensity spectra were measured in an approximately \ifmmode\pm\else\textpm\fi{}50-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the atomic Mg 3s $^{1}$ ${\mathit{S}}_{0}$ \ensuremath{\rightarrow}3p $^{1}$ ${\mathit{P}}_{1}$ \ensuremath{\rightarrow}5s $^{1}$ ${\mathit{S}}_{0}$ two-photon resonance. The generally-weak-field spectra show a remarkable phenomenology associated with the relative linear-polarization directions of the two exciting laser beams and with their separate detunings from atomic one-photon resonance. The polarization and relative absorption spectra display effects due to relative detuning, multiple Condon points, and laser intensity. Details of our experimental approach, and spectra for the process in Mg-Ar and Mg-Ne are presented and discussed. The data are seen to contain information on the short-range collision dynamics of the Mg--rare-gas pairs, and on the development of the alignment over the course of the collision.Extensive experimental studies of Mg-Ne and Mg-Ar fractional collisions are reported. In the fractional-collision process, two-color, two-photon absorption takes place during a single binary collision. Polarization and relative intensity spectra were measured in an approximately \ifmmode\pm\else\textpm\fi{}50-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the atomic Mg 3s $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}3p $^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}5s $^{1}$${\mathit{S}}_{0}$ two-photon resonance. The generally-weak-field spectra show a remarkable phenomenology associated with the relative linear-polarization directions of the two exciting laser beams and with their separate detunings from atomic one-photon resonance. The polarization and relative absorption spectra display effects due to relative detuning, multiple Condon points, and laser intensity. Details of our experimental approach, and spectra for the process in Mg-Ar and Mg-Ne are presented and discussed. The data are seen to contain information on the short-range collision dynamics of the Mg--rare-gas pairs, and on the development of the alignment over the course of the collision.

Physical Review ASep 1, 199310 citations

Two-photon absorption by atoms perturbed by collisions

Gerard Nienhuis, F. Schuller

Physica B+CJun 1, 19784 citations

Far Wing Depolarization of Light: Generalized Absorption Profiles

P. Thomann, Keith R. Burnett, J. Cooper

An absorption (and/or emission) event which takes place during a strong collision is called a 'correlated event'. It is discussed how correlated events affect the far red wing depolarization of fluorescence. Attention is given to an atomic vapor which is irradiated by linearly polarized light of a frequency on the red side of the resonance line. Two limiting cases are considered, corresponding to excitation in the impact region and in the quasi-static wing. In the quasi-static wing, absorption of a photon followed by fluorescence (rather than Rayleigh scattering), occurs mostly during a collision. Correlated events dominate the scattering process. Expressions derived for the polarization of the fluorescent light are applied to far red wing depolarization. It is found that the polarization of the fluorescent light does not go to zero in the far wing, but depends crucially on the detailed nature of the anisotropy in the long-range part of the interatomic potential.An absorption (and/or emission) event which takes place during a strong collision is called a 'correlated event'. It is discussed how correlated events affect the far red wing depolarization of fluorescence. Attention is given to an atomic vapor which is irradiated by linearly polarized light of a frequency on the red side of the resonance line. Two limiting cases are considered, corresponding to excitation in the impact region and in the quasi-static wing. In the quasi-static wing, absorption of a photon followed by fluorescence (rather than Rayleigh scattering), occurs mostly during a collision. Correlated events dominate the scattering process. Expressions derived for the polarization of the fluorescent light are applied to far red wing depolarization. It is found that the polarization of the fluorescent light does not go to zero in the far wing, but depends crucially on the detailed nature of the anisotropy in the long-range part of the interatomic potential.

De Gruyter eBooksDec 31, 19810 citations

Theory of Two-Photon Absorption

清西川, 昭佐道, Hiroshi Sekiya +3 more

Jun 1, 19770 citations

^{1}

{\mathit{S}}_{0}

\ensuremath{\rightarrow}3p

^{1}

{\mathit{P}}_{1}

\ensuremath{\rightarrow}5s

^{1}

{\mathit{S}}_{0}

two-photon resonance. The generally-weak-field spectra show a remarkable phenomenology associated with the relative linear-polarization directions of the two exciting laser beams and with their separate detunings from atomic one-photon resonance. The polarization and relative absorption spectra display effects due to relative detuning, multiple Condon points, and laser intensity. Details of our experimental approach, and spectra for the process in Mg-Ar and Mg-Ne are presented and discussed. The data are seen to contain information on the short-range collision dynamics of the Mg--rare-gas pairs, and on the development of the alignment over the course of the collision.