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Physical Review A

mJ Mixing in Oriented 4P322 Potassium Atoms Induced by Collisions with Inert Gases

W. Berdowski, T. Shiner, L. Krause

Published Sep 1, 1971• 24 citations
Publisher

Abstract

The cross sections for the decay of circular and of linear polarization in oriented $4^{2}P_{\frac{3}{2}}$ potassium atoms, induced in collision with inert-gas atoms, were determined in a series of fluorescence experiments. A modified Zeeman scanning method was used to populate selectively the ${m}_{J}$ sublevels of the $^{2}P_{\frac{3}{2}}$ potassium atoms mixed with inert gases and placed in a strong magnetic field. Measurements of depolarization of the fluorescence, in relation to gas pressures, yielded the following depolarization cross sections: ${\ensuremath{\sigma}}_{1}$ (disorientation): K-He, 86 ${\mathrm{\AA{}}}^{2}$; K-Ne, 86 ${\mathrm{\AA{}}}^{2}$; K-Ar, 164 ${\mathrm{\AA{}}}^{2}$; K-Kr, 248 ${\mathrm{\AA{}}}^{2}$; K-Xe, 251 \AA{}. ${\ensuremath{\sigma}}_{2}$ (disalignment): K-He, 127 \AA{}; K-Ne, 120 ${\mathrm{\AA{}}}^{2}$; K-Ar, 240 ${\mathrm{\AA{}}}^{2}$, K-Kr, 301 ${\mathrm{\AA{}}}^{2}$, K-Xe, 336 ${\mathrm{\AA{}}}^{2}$. The experimental values are in satisfactory agreement with the calculations of Nikitin and Ovchinnikova.

DOI
10.1103/physreva.4.984

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mJ Mixing in Oriented 4P122 Potassium Atoms, Induced by Collisions with Inert Gases

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A modified Zeeman scanning method was used to excite selectively the magnetic substates of the $4^{2}P_{\frac{1}{2}}$ potassium atoms mixed with inert gases and placed in a strong magnetic field. The resulting potassium-inert-gas atomic collisions induced ${m}_{J}$ mixing in potassium, which manifested itself by the depolarization of the potassium resonance fluorescence. The polarization measurements yielded the following disorientation cross sections: K-He: 46 ${\mathrm{\AA{}}}^{2}$; K-Ne: 39 ${\mathrm{\AA{}}}^{2}$; K-A: 52 ${\mathrm{\AA{}}}^{2}$; K-Kr: 80 ${\mathrm{\AA{}}}^{2}$; K-Xe: 107 ${\mathrm{\AA{}}}^{2}$.

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The cross sections for disorientation of magnetically oriented $6^{2}P_{\frac{1}{2}}$ cesium atoms, induced in collisions with noble gases, have been determined using Zeeman-scanning techniques at kilogauss magnetic fields. The ${m}_{J}=\ensuremath{-}\frac{1}{2}$, ${m}_{I}=\ensuremath{-}\frac{7}{2}$ hyperfine Zeeman substate was populated selectively by irradiating the cesium-vapor-noble-gas mixture with cesium-resonance radiation, and collisional transitions to the ${m}_{J}=+\frac{1}{2}$, ${m}_{I}=\ensuremath{-}\frac{7}{2}$ substate were monitored by measurements of the relative intensities of the ${\ensuremath{\sigma}}^{\ensuremath{-}}$ and ${\ensuremath{\sigma}}^{+}$ components in resonance fluorescence observed in the direction parallel to the magnetic field. The following cross sections were obtained: Cs-He, 11.8 ${\mathrm{\AA{}}}^{2}$; Cs-Ne, 4.7 ${\mathrm{\AA{}}}^{2}$; Cs-Ar, 10.7 ${\mathrm{\AA{}}}^{2}$; Cs-Kr, 37.9 ${\mathrm{\AA{}}}^{2}$; Cs-Xe, 71.7 ${\mathrm{\AA{}}}^{2}$.

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Disorientation of K(42P1/2) Atoms, Induced in Collisions with Noble Gases

B. Niewitecka, L. Krause

The cross sections for disorientation of 42P1/2 potassium atoms, induced in collisions with noble gas atoms, have been determined in zero magnetic field by studying the depolarization of K(7699 Å) resonance fluorescence in relation to noble gas pressures. Potassium vapor at low density, mixed with a noble gas in a fluorescence vessel, was irradiated with circularly polarized 7699 Å potassium resonance radiation and the resulting resonance fluorescence, observed in an approximately backward direction, was analyzed with respect to circular polarization. The variation of the degree of polarization with gas pressure was interpreted on the basis of a 'J randomization' model for the collisions and yielded the following disorientation cross sections which are appropriately corrected for the effect of nuclear spin: K–He, 24 ± 4 Å2; K–Ne, 21 ± 3 Å2; K–Ar, 37 ± 5 Å2; K–Kr, 51 ± 7 Å2; K–Xe, 69 ± 9 Å2. The cross sections are significantly smaller than values obtained previously in kilogauss fields.

Canadian Journal of Physics•Aug 1, 1975•13 citations

Depolarization of 6P322 cesium atoms, induced in collisions with noble gases

J. Guiry, L. Krause

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Physical Review A•Dec 1, 1976•13 citations

Collisional m(J) mixing in magnetically oriented 4(2)P(3/2) potassium atoms.

T. Shiner

The mj mixing cross section for disorientation of magnetically 2 oriented potassium atoms in the 4 ^2/2 state» induced by collisions with ground state helium atoms, was measured using a modified Zeeman scanning technique.The mj substates of potassium atoms, situated in a strong magnetic field, were selectively excited and the collisionally induced mixing manifested itself by the depolarization of the potassium resonance fluorescence.The depolarization measurements yielded mixing cross -14 2 -14 2 sections ranging from 0.77 x 10 cm to 1.4 x 10 cm .It is felt that this discrepancy may be due to a selection rule for transitions between the fine structure states such that £nij = 0 is preferred.

•Jan 1, 1967•0 citations

Collisional mJ mixing and multipole relaxation in 4P2 potassium atoms

P. Skalinski, L. Krause

${m}_{J}$ mixing in $4^{2}P_{\frac{1}{2}}$ and $4^{2}P_{\frac{3}{2}}$ potassium atoms as well as atomic multipole relaxation induced in K-K and K-Ar collisions were investigated by methods of atomic fluorescence spectroscopy. K vapor, pure or mixed with Ar, was placed in a kG magnetic field and irradiated with a single Zeeman component of 7665- or 7699-\AA{} resonance radiation, causing the selective excitation of the $^{2}P_{\frac{1}{2},\ensuremath{-}\frac{1}{2}}$ or $^{2}P_{\frac{3}{2},\ensuremath{-}\frac{3}{2}}$ substate. Collisions of the excited atoms with ground-state K or Ar atoms caused ${m}_{J}$ mixing which was monitored by analysis of the resulting fluorescent spectrum with a scanning Fabry-Perot interferometer. Intensity measurements on the fluorescent Zeeman components in relation to ground-state atomic densities yielded the following multipole relaxation cross sections ${\ensuremath{\Lambda}}_{J}^{(L)}$: K-K (${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{2}$): ${\ensuremath{\Lambda}}_{\frac{1}{2}}^{(1)}=5.7\ifmmode\pm\else\textpm\fi{}0.9$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(1)}=8.1\ifmmode\pm\else\textpm\fi{}1.4$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(2)}=11.4\ifmmode\pm\else\textpm\fi{}2.0$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(3)}=9.8\ifmmode\pm\else\textpm\fi{}1.5$; K-Ar (${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$): ${\ensuremath{\Lambda}}_{\frac{1}{2}}^{(1)}=65\ifmmode\pm\else\textpm\fi{}10$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(1)}=175\ifmmode\pm\else\textpm\fi{}25$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(2)}=230\ifmmode\pm\else\textpm\fi{}35$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(3)}=190\ifmmode\pm\else\textpm\fi{}30$. The ${Q}_{J}(m\ensuremath{\leftrightarrow}{m}^{\ensuremath{'}})$ cross sections for ${m}_{J}$ mixing were derived from the ${\ensuremath{\Lambda}}_{J}^{(L)}$ as well as the cross sections for multipole decay ${\ensuremath{\sigma}}_{J}^{(L)}={\ensuremath{\Lambda}}_{J}^{(L)}+{\ensuremath{\sigma}}_{J}^{(0)}$. The experimental results are in good agreement with theoretical calculations.

Physical Review A•Dec 1, 1982•12 citations
The cross sections for the decay of circular and of linear polarization in oriented 42P324^{2}P_{\frac{3}{2}}42P23​​ potassium atoms, induced in collision with inert-gas atoms, were determined in a series of fluorescence experiments. A modified Zeeman scanning method was used to populate selectively the mJ{m}_{J}mJ​ sublevels of the 2P32^{2}P_{\frac{3}{2}}2P23​​ potassium atoms mixed with inert gases and placed in a strong magnetic field. Measurements of depolarization of the fluorescence, in relation to gas pressures, yielded the following depolarization cross sections: \ensuremathσ1{\ensuremath{\sigma}}_{1}\ensuremathσ1​ (disorientation): K-He, 86 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Ne, 86 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Ar, 164 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Kr, 248 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Xe, 251 \AA{}. \ensuremathσ2{\ensuremath{\sigma}}_{2}\ensuremathσ2​ (disalignment): K-He, 127 \AA{}; K-Ne, 120 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Ar, 240 A˚2{\mathrm{\AA{}}}^{2}A˚2, K-Kr, 301 A˚2{\mathrm{\AA{}}}^{2}A˚2, K-Xe, 336 A˚2{\mathrm{\AA{}}}^{2}A˚2. The experimental values are in satisfactory agreement with the calculations of Nikitin and Ovchinnikova.
A modified Zeeman scanning method was used to excite selectively the magnetic substates of the 42P124^{2}P_{\frac{1}{2}}42P21​​ potassium atoms mixed with inert gases and placed in a strong magnetic field. The resulting potassium-inert-gas atomic collisions induced mJ{m}_{J}mJ​ mixing in potassium, which manifested itself by the depolarization of the potassium resonance fluorescence. The polarization measurements yielded the following disorientation cross sections: K-He: 46 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Ne: 39 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-A: 52 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Kr: 80 A˚2{\mathrm{\AA{}}}^{2}A˚2; K-Xe: 107 A˚2{\mathrm{\AA{}}}^{2}A˚2.
The cross sections for disorientation of magnetically oriented 62P126^{2}P_{\frac{1}{2}}62P21​​ cesium atoms, induced in collisions with noble gases, have been determined using Zeeman-scanning techniques at kilogauss magnetic fields. The ${m}_{J}=\ensuremath{-}\frac{1}{2}$, ${m}_{I}=\ensuremath{-}\frac{7}{2}$ hyperfine Zeeman substate was populated selectively by irradiating the cesium-vapor-noble-gas mixture with cesium-resonance radiation, and collisional transitions to the mJ=+12{m}_{J}=+\frac{1}{2}mJ​=+21​, ${m}_{I}=\ensuremath{-}\frac{7}{2}$ substate were monitored by measurements of the relative intensities of the ${\ensuremath{\sigma}}^{\ensuremath{-}}$ and ${\ensuremath{\sigma}}^{+}$ components in resonance fluorescence observed in the direction parallel to the magnetic field. The following cross sections were obtained: Cs-He, 11.8 A˚2{\mathrm{\AA{}}}^{2}A˚2; Cs-Ne, 4.7 A˚2{\mathrm{\AA{}}}^{2}A˚2; Cs-Ar, 10.7 A˚2{\mathrm{\AA{}}}^{2}A˚2; Cs-Kr, 37.9 A˚2{\mathrm{\AA{}}}^{2}A˚2; Cs-Xe, 71.7 A˚2{\mathrm{\AA{}}}^{2}A˚2.
The cross sections for disorientation of 42P1/2 potassium atoms, induced in collisions with noble gas atoms, have been determined in zero magnetic field by studying the depolarization of K(7699 Å) resonance fluorescence in relation to noble gas pressures. Potassium vapor at low density, mixed with a noble gas in a fluorescence vessel, was irradiated with circularly polarized 7699 Å potassium resonance radiation and the resulting resonance fluorescence, observed in an approximately backward direction, was analyzed with respect to circular polarization. The variation of the degree of polarization with gas pressure was interpreted on the basis of a 'J randomization' model for the collisions and yielded the following disorientation cross sections which are appropriately corrected for the effect of nuclear spin: K–He, 24 ± 4 Å2; K–Ne, 21 ± 3 Å2; K–Ar, 37 ± 5 Å2; K–Kr, 51 ± 7 Å2; K–Xe, 69 ± 9 Å2. The cross sections are significantly smaller than values obtained previously in kilogauss fields.
Cross sections for relaxation of circular and linear polarization of 62P326^{2}P_{\frac{3}{2}}62P23​​ cesium atoms, induced in collisions with ground-state He, Ne, Ar, and Xe, have been determined by Zeeman scanning techniques. A fluorescence cell containing low-pressure cesium vapor together with a buffer gas was irradiated with circularly or linearly polarized 8521-\AA{} Cs resonance radiation, producing excited and polarized Cs atoms which became depolarized in subsequent collisions with the buffer-gas atoms. The resulting depolarization of the cesium resonance fluorescence was monitored in relation to buffer-gas pressure (0-10 Torr) and to the strength of the ambient magnetic field (0-10 kG). At low fields at which the nuclear spin $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ is coupled to the electronic angular momentum $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$, the measurements yielded depolarization cross sections Q(circ.)Q(\mathrm{circ}.)Q(circ.) and Q(lin.)Q(\mathrm{lin}.)Q(lin.), which agree within experimental error with theoretical values calculated for spin-coupled conditions. At kilogauss fields with $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$ decoupled, the experiments produced cross sections for disorientation and disalignment, which are also in satisfactory agreement with the appropriate theoretical predictions. The results indicate that the nuclear spin has a more pronounced effect on the collisional relaxation of the atomic dipole than of the quadrupole.
The mj mixing cross section for disorientation of magnetically 2 oriented potassium atoms in the 4 ^2/2 state» induced by collisions with ground state helium atoms, was measured using a modified Zeeman scanning technique.The mj substates of potassium atoms, situated in a strong magnetic field, were selectively excited and the collisionally induced mixing manifested itself by the depolarization of the potassium resonance fluorescence.The depolarization measurements yielded mixing cross -14 2 -14 2 sections ranging from 0.77 x 10 cm to 1.4 x 10 cm .It is felt that this discrepancy may be due to a selection rule for transitions between the fine structure states such that £nij = 0 is preferred.
mJ{m}_{J}mJ​ mixing in 42P124^{2}P_{\frac{1}{2}}42P21​​ and 42P324^{2}P_{\frac{3}{2}}42P23​​ potassium atoms as well as atomic multipole relaxation induced in K-K and K-Ar collisions were investigated by methods of atomic fluorescence spectroscopy. K vapor, pure or mixed with Ar, was placed in a kG magnetic field and irradiated with a single Zeeman component of 7665- or 7699-\AA{} resonance radiation, causing the selective excitation of the $^{2}P_{\frac{1}{2},\ensuremath{-}\frac{1}{2}}$ or $^{2}P_{\frac{3}{2},\ensuremath{-}\frac{3}{2}}$ substate. Collisions of the excited atoms with ground-state K or Ar atoms caused mJ{m}_{J}mJ​ mixing which was monitored by analysis of the resulting fluorescent spectrum with a scanning Fabry-Perot interferometer. Intensity measurements on the fluorescent Zeeman components in relation to ground-state atomic densities yielded the following multipole relaxation cross sections ${\ensuremath{\Lambda}}_{J}^{(L)}$: K-K (${10}^{\ensuremath{-}12}$ cm2{\mathrm{cm}}^{2}cm2): ${\ensuremath{\Lambda}}_{\frac{1}{2}}^{(1)}=5.7\ifmmode\pm\else\textpm\fi{}0.9$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(1)}=8.1\ifmmode\pm\else\textpm\fi{}1.4$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(2)}=11.4\ifmmode\pm\else\textpm\fi{}2.0$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(3)}=9.8\ifmmode\pm\else\textpm\fi{}1.5$; K-Ar (${10}^{\ensuremath{-}16}$ cm2{\mathrm{cm}}^{2}cm2): ${\ensuremath{\Lambda}}_{\frac{1}{2}}^{(1)}=65\ifmmode\pm\else\textpm\fi{}10$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(1)}=175\ifmmode\pm\else\textpm\fi{}25$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(2)}=230\ifmmode\pm\else\textpm\fi{}35$, ${\ensuremath{\Lambda}}_{\frac{3}{2}}^{(3)}=190\ifmmode\pm\else\textpm\fi{}30$. The ${Q}_{J}(m\ensuremath{\leftrightarrow}{m}^{\ensuremath{'}})$ cross sections for mJ{m}_{J}mJ​ mixing were derived from the ${\ensuremath{\Lambda}}_{J}^{(L)}$ as well as the cross sections for multipole decay ${\ensuremath{\sigma}}_{J}^{(L)}={\ensuremath{\Lambda}}_{J}^{(L)}+{\ensuremath{\sigma}}_{J}^{(0)}$. The experimental results are in good agreement with theoretical calculations.