Physical Review Letters

Observation of Laser-Induced Penning and Associative Ionization in Li-Li Collisions

A. v. Hellfeld, J. Caddick, J. Weiner

Published May 22, 1978• 74 citations

Abstract

We report the direct observation of $^{6}\mathrm{Li}^{+}$, $^{7}\mathrm{Li}^{+}$, $^{13}\mathrm{Li}_{2}^{+}$, $^{14}\mathrm{Li}_{2}^{+}$ arising from single collisions between beams of lithium atoms in the presence of a laser field. Although the relative intensity of atomic ions reflects the natural isotopic abundance, a pronounced enrichment of $^{13}\mathrm{Li}_{2}^{+}$ relative to $^{14}\mathrm{Li}_{2}^{+}$ is observed.

DOI: 10.1103/physrevlett.40.1369

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Physical Review Letters

Observation of Laser-Induced Penning and Associative Ionization in Li-Li Collisions

A. v. Hellfeld, J. Caddick, J. Weiner

Published May 22, 1978• 74 citations

Publisher

Abstract

We report the direct observation of

^{6}\mathrm{Li}^{+}

^{7}\mathrm{Li}^{+}

^{13}\mathrm{Li}_{2}^{+}

^{14}\mathrm{Li}_{2}^{+}

arising from single collisions between beams of lithium atoms in the presence of a laser field. Although the relative intensity of atomic ions reflects the natural isotopic abundance, a pronounced enrichment of

^{13}\mathrm{Li}_{2}^{+}

relative to

^{14}\mathrm{Li}_{2}^{+}

is observed.

DOI: 10.1103/physrevlett.40.1369

Related papers

Observation of Structure in Laser-Induced Penning and Associative Ionization in Crossed-Beam Na + Na Collisions

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Evgueni V. Kovarski

The near resonant cooling mechanism have offered for the experiment with laser induced excitation of Lithium isotopes and its ionization by collisions.

arXiv:physics/0107042Jul 18, 20010 citations

Laser isotope enrichment of lithium by magnetic deflection of a polarized atomic beam

Zhu Xiwen, Huang Gui-long, Mei Ganghua +1 more

The authors have succeeded in demonstrating laser isotope enrichment via magnetic deflection of a polarized atomic beam. By using a single dye laser with the frequency tuned to the two accidentally close transitions of the natural lithium (2 2 S 1/2 (F=1/2) to 2 2 P 3/2 for 6 Li and 2 2 S 1/2 (F=2) to 2 2 P 1 2/(F=1) for 7 Li), 6 Li and 7 Li atoms in a beam were positively and negatively polarized respectively. The 6 Li enrichment was achieved via magnetic deflection of the polarized beam through a hexapole magnet which focuses the positively polarized 6 Li atoms and defocuses the negatively polarized 7 Li atoms. The dependence of 7 Li polarization on laser intensity was experimentally examined, and the result was in good agreement with that calculated by rate equations. The abundance ratio of 6 Li to 7 Li was enhanced from 1 : 12.5 to about 1 : 3.1.The authors have succeeded in demonstrating laser isotope enrichment via magnetic deflection of a polarized atomic beam. By using a single dye laser with the frequency tuned to the two accidentally close transitions of the natural lithium (2 2 S 1/2 (F=1/2) to 2 2 P 3/2 for 6 Li and 2 2 S 1/2 (F=2) to 2 2 P 1 2/(F=1) for 7 Li), 6 Li and 7 Li atoms in a beam were positively and negatively polarized respectively. The 6 Li enrichment was achieved via magnetic deflection of the polarized beam through a hexapole magnet which focuses the positively polarized 6 Li atoms and defocuses the negatively polarized 7 Li atoms. The dependence of 7 Li polarization on laser intensity was experimentally examined, and the result was in good agreement with that calculated by rate equations. The abundance ratio of 6 Li to 7 Li was enhanced from 1 : 12.5 to about 1 : 3.1.

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Resonant Light Absorption in a Penning-Ionization Collision

James H. Goble, William E. Hollingsworth, John S. Winn

The opening of a new channel of excitative Penning ionization by a collision-complex absorption of laser light has been observed in the system Ar*( $^{3}P$ ) + Ca. Two relatively broad resonances at 5958 and 5990 \AA{} were found, corresponding to the production of ${\mathrm{Ca}}^{+}$ ( $5p^{2}P_{\frac{3}{2}}$ ) and ${\mathrm{Ca}}^{+}$ ( $5p^{2}P_{\frac{1}{2}}$ ), respectively. The data indicate that the laser-assisted Penning-ionization cross section to these states exceeds that of the field-free ionization to ${\mathrm{Ca}}^{+}$ ( $4p^{2}P_{\frac{3}{2}}$ ).The opening of a new channel of excitative Penning ionization by a collision-complex absorption of laser light has been observed in the system Ar*($^{3}P$) + Ca. Two relatively broad resonances at 5958 and 5990 \AA{} were found, corresponding to the production of ${\mathrm{Ca}}^{+}$($5p^{2}P_{\frac{3}{2}}$) and ${\mathrm{Ca}}^{+}$($5p^{2}P_{\frac{1}{2}}$), respectively. The data indicate that the laser-assisted Penning-ionization cross section to these states exceeds that of the field-free ionization to ${\mathrm{Ca}}^{+}$($4p^{2}P_{\frac{3}{2}}$).

Physical Review LettersDec 28, 19817 citations

We report the direct observation of

^{6}\mathrm{Li}^{+}

^{7}\mathrm{Li}^{+}

^{13}\mathrm{Li}_{2}^{+}

^{14}\mathrm{Li}_{2}^{+}

^{13}\mathrm{Li}_{2}^{+}

relative to

^{14}\mathrm{Li}_{2}^{+}

is observed.

The results of double-laser experiments in which

{\mathrm{Na}}_{2}^{+}

and

{\mathrm{Na}}^{+}

are produced in crossed alkali beams under single-collision conditions in the presence of strong optical fields are reported. Structure in the mass-selected product ion intensity as a function laser frequency is observed when the optical field is strongly focused and tuned far off atomic or dimer transitions. These measurements are the first to show that the nuclear motion of the quasimolecular collision intermediate plays an important role in laser-induced collisional ionization.

The opening of a new channel of excitative Penning ionization by a collision-complex absorption of laser light has been observed in the system Ar*(

^{3}P

) + Ca. Two relatively broad resonances at 5958 and 5990 \AA{} were found, corresponding to the production of

{\mathrm{Ca}}^{+}

(

5p^{2}P_{\frac{3}{2}}

) and

{\mathrm{Ca}}^{+}

(

5p^{2}P_{\frac{1}{2}}

), respectively. The data indicate that the laser-assisted Penning-ionization cross section to these states exceeds that of the field-free ionization to

{\mathrm{Ca}}^{+}

(

4p^{2}P_{\frac{3}{2}}