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Physical Review

Radiative Lifetime of the First P322 State of Ionized Calcium and Magnesium by the Hanle Effect

W. W. Smith, Alan C. Gallagher

Published May 6, 1966• 136 citations
Publisher

Abstract

The lifetime of the ${\mathrm{Ca}}^{+}$ $4^{2}P_{\frac{3}{2}}$ state and that of the ${\mathrm{Mg}}^{+}$ $3^{2}P_{\frac{3}{2}}$ state have been measured by the Hanle-effect method with optical excitation from the ground states of the ions. The lifetimes are, respectively, (6.72\ifmmode\pm\else\textpm\fi{}0.20)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ and (3.67\ifmmode\pm\else\textpm\fi{}0.18)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. The ions were produced by introducing traces of calcium or magnesium into an argon discharge. "Alignment" depolarization cross sections $\ensuremath{\sigma}$ were obtained for the collisional depolarization of the following states of calcium and magnesium due to collisions with argon: $\ensuremath{\sigma}(\mathrm{Ca} 4^{1}P_{1} \mathrm{state})=(1.9\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};$ $\ensuremath{\sigma}({\mathrm{Ca}}^{+} 4^{2}P_{\frac{3}{2}} \mathrm{state})=(1.4\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};$ $\ensuremath{\sigma}(\mathrm{Mg} 3^{1}P_{1} \mathrm{state})=(1.9\ifmmode\pm\else\textpm\fi{}0.3){10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};$ $\ensuremath{\sigma}({\mathrm{Mg}}^{+} 3^{2}P_{\frac{3}{2}} \mathrm{state})=(1.3\ifmmode\pm\else\textpm\fi{}0.25)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2}.$The magnitudes of these cross sections are in accord with the theories of Byron and Foley and of Omont; we give a discussion of the extension of these theories to include ion-atom collisions.

DOI
10.1103/physrev.145.26

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The lifetime of the Ca+{\mathrm{Ca}}^{+}Ca+ 42P324^{2}P_{\frac{3}{2}}42P23​​ state and that of the Mg+{\mathrm{Mg}}^{+}Mg+ 32P323^{2}P_{\frac{3}{2}}32P23​​ state have been measured by the Hanle-effect method with optical excitation from the ground states of the ions. The lifetimes are, respectively, (6.72\ifmmode\pm\else\textpm\fi{}0.20)\ifmmode\times\else\texttimes\fi{}10\ensuremath−9{10}^{\ensuremath{-}9}10\ensuremath−9 and (3.67\ifmmode\pm\else\textpm\fi{}0.18)\ifmmode\times\else\texttimes\fi{}10\ensuremath−9{10}^{\ensuremath{-}9}10\ensuremath−9 sec. The ions were produced by introducing traces of calcium or magnesium into an argon discharge. "Alignment" depolarization cross sections \ensuremathσ\ensuremath{\sigma}\ensuremathσ were obtained for the collisional depolarization of the following states of calcium and magnesium due to collisions with argon: \ensuremathσ(Ca41P1state)=(1.9\ifmmode±\else\textpm\fi0.3)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2;\ensuremath{\sigma}(\mathrm{Ca} 4^{1}P_{1} \mathrm{state})=(1.9\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};\ensuremathσ(Ca41P1​state)=(1.9\ifmmode±\else\textpm\fi0.3)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2; \ensuremathσ(Ca+42P32state)=(1.4\ifmmode±\else\textpm\fi0.2)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2;\ensuremath{\sigma}({\mathrm{Ca}}^{+} 4^{2}P_{\frac{3}{2}} \mathrm{state})=(1.4\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};\ensuremathσ(Ca+42P23​​state)=(1.4\ifmmode±\else\textpm\fi0.2)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2; \ensuremathσ(Mg31P1state)=(1.9\ifmmode±\else\textpm\fi0.3)10\ensuremath−14cm2;\ensuremath{\sigma}(\mathrm{Mg} 3^{1}P_{1} \mathrm{state})=(1.9\ifmmode\pm\else\textpm\fi{}0.3){10}^{\ensuremath{-}14}{\mathrm{cm}}^{2};\ensuremathσ(Mg31P1​state)=(1.9\ifmmode±\else\textpm\fi0.3)10\ensuremath−14cm2; \ensuremathσ(Mg+32P32state)=(1.3\ifmmode±\else\textpm\fi0.25)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2.\ensuremath{\sigma}({\mathrm{Mg}}^{+} 3^{2}P_{\frac{3}{2}} \mathrm{state})=(1.3\ifmmode\pm\else\textpm\fi{}0.25)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}{\mathrm{cm}}^{2}.\ensuremathσ(Mg+32P23​​state)=(1.3\ifmmode±\else\textpm\fi0.25)\ifmmode×\else\texttimes\fi10\ensuremath−14cm2.The magnitudes of these cross sections are in accord with the theories of Byron and Foley and of Omont; we give a discussion of the extension of these theories to include ion-atom collisions.
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