Physical Review A

Residual-ion orientation after autoionization

G. T. Xu, Xiao Wang, J. G. Story, William E. Cooke

Published Apr 1, 1993• 4 citations

Abstract

We have measured the relative population in the two ${\mathit{m}}_{\mathit{j}}$ states of barium 6${\mathit{p}}_{1/2}$ ions produced by the autoionization of (6${\mathit{p}}_{3/2}$nd${)}_{\mathit{J}=\mathit{M}\mathit{J}}$=3 states by detecting the helicity of the emitted fluorescence. These populations can be related to the relative branching ratio into the 6${\mathit{p}}_{1/2}$\ensuremath{\epsilon}${\mathit{d}}_{5/2}$ and 6${\mathit{p}}_{1/2}$\ensuremath{\epsilon}${\mathit{g}}_{7/2}$ continuum channels. Rydberg states with n=16--23 have similar branching ratios, producing approximately six times as much 6${\mathit{p}}_{1/2}$\ensuremath{\epsilon}${\mathit{d}}_{5/2}$ population as 6${\mathit{p}}_{1/2}$\ensuremath{\epsilon}${\mathit{g}}_{7/2}$ population.

DOI: 10.1103/physreva.47.r2438

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Electric field-induced changes in the autoionization branching ratios of the 6p{sub 1/2}nd J = 3 states of barium

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We report a measurement of the branching ratio for production of 5d{sub 3/2} ions in various m{sub j} states following the autoionization of the (6{sub p1/2}nd{sub 5/2})J=M{sub J}=3 states of barium in an electric field. By detecting the population in different ion states, rather than the electron distribution, we are able to measure the decay routes even in the presence of an electric field. These branching ratios show pronounced new structure, even at fields as low as 30 V/cm.

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Physical Review A

Residual-ion orientation after autoionization

G. T. Xu, Xiao Wang, J. G. Story, William E. Cooke

Published Apr 1, 1993• 4 citations

Publisher

Abstract

We have measured the relative population in the two

{\mathit{m}}_{\mathit{j}}

states of barium 6

{\mathit{p}}_{1/2}

ions produced by the autoionization of (6

{\mathit{p}}_{3/2}

{)}_{\mathit{J}=\mathit{M}\mathit{J}}

=3 states by detecting the helicity of the emitted fluorescence. These populations can be related to the relative branching ratio into the 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{d}}_{5/2}

and 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{g}}_{7/2}

continuum channels. Rydberg states with n=16--23 have similar branching ratios, producing approximately six times as much 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{d}}_{5/2}

population as 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{g}}_{7/2}

population.

DOI: 10.1103/physreva.47.r2438

Related papers

Spectroscopy of autoionizing states using state-selective ion detection

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The authors have measured the population in each of the 5d 3/2 (m j ) ion states following autoionization of the (6p 3/2 nd) J=MJ=3 state by using a circularly polarized laser to excite the Ba + 5d 3/2 to 6p 1 2/ transition, and observing the polarized fluorescence of the Ba + 6p 1/2 to 6s 1/2 transition. The branching ratios for autoionization into each of the 5d 3/2 in l j channels can be related to these ion populations by using angular momentum algebra. The fractions of ions found in the m j =+3/2, +1/2, -1/2 and -3.2 state of the 5d 3/2 ion states were 5.9(+or-2.6)%, 4.5(+or-1.9)%, 3.2(+or-1.3)% and 1.9(+or-0.6)% respectively. This method can easily be generalized to measure the branching ratio for autoonization into other ion states.The authors have measured the population in each of the 5d 3/2 (m j ) ion states following autoionization of the (6p 3/2 nd) J=MJ=3 state by using a circularly polarized laser to excite the Ba + 5d 3/2 to 6p 1 2/ transition, and observing the polarized fluorescence of the Ba + 6p 1/2 to 6s 1/2 transition. The branching ratios for autoionization into each of the 5d 3/2 in l j channels can be related to these ion populations by using angular momentum algebra. The fractions of ions found in the m j =+3/2, +1/2, -1/2 and -3.2 state of the 5d 3/2 ion states were 5.9(+or-2.6)%, 4.5(+or-1.9)%, 3.2(+or-1.3)% and 1.9(+or-0.6)% respectively. This method can easily be generalized to measure the branching ratio for autoonization into other ion states.

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Effects of electric fields on doubly excited autoionizing Rydberg states of barium

Kambiz Ali Safinya, J. F. Delpech, Thomas F. Gallagher

We report the effects of static electric fields on the doubly excited $6{p}_{\frac{1}{2}}\mathrm{nl}$ states of barium in the region ${n}^{*}=12$ . Using a three-step laser excitation scheme we have measured the electric-field dependence of the positions and autoionization widths of the $6{p}_{\frac{1}{2}}\ensuremath{-}17s,16p,15d,12l (l=4\ensuremath{-}10),12f, \mathrm{and} 16s$ states at field values of up to 4.92 kV/cm. The photoexcitation spectra of the autoionizing states exhibit interference effects which are well understood and provide a better understanding of the character of these states in electric fields. The systematic study of the spectra and positions allows us to explain the field dependence of the autoionization widths in terms of electric-field mixing of the discrete portions of the auoionizing states. The relationship of these effects to dielectronic recombination rates of ions and electrons in plasma microfields is discussed.We report the effects of static electric fields on the doubly excited $6{p}_{\frac{1}{2}}\mathrm{nl}$ states of barium in the region ${n}^{*}=12$. Using a three-step laser excitation scheme we have measured the electric-field dependence of the positions and autoionization widths of the $6{p}_{\frac{1}{2}}\ensuremath{-}17s,16p,15d,12l (l=4\ensuremath{-}10),12f, \mathrm{and} 16s$ states at field values of up to 4.92 kV/cm. The photoexcitation spectra of the autoionizing states exhibit interference effects which are well understood and provide a better understanding of the character of these states in electric fields. The systematic study of the spectra and positions allows us to explain the field dependence of the autoionization widths in terms of electric-field mixing of the discrete portions of the auoionizing states. The relationship of these effects to dielectronic recombination rates of ions and electrons in plasma microfields is discussed.

Physical Review ASep 1, 198020 citations

We have measured the relative population in the two

{\mathit{m}}_{\mathit{j}}

states of barium 6

{\mathit{p}}_{1/2}

ions produced by the autoionization of (6

{\mathit{p}}_{3/2}

{)}_{\mathit{J}=\mathit{M}\mathit{J}}

=3 states by detecting the helicity of the emitted fluorescence. These populations can be related to the relative branching ratio into the 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{d}}_{5/2}

and 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{g}}_{7/2}

continuum channels. Rydberg states with n=16--23 have similar branching ratios, producing approximately six times as much 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{d}}_{5/2}

population as 6

{\mathit{p}}_{1/2}

\ensuremath{\epsilon}

{\mathit{g}}_{7/2}

population.

A two-step process using internal conversion and fluorescence to stabilize the

6{P}_{\frac{3}{2}}11d

autoionizing state of barium has been observed. The internal conversion produces very highly excited autoionizing Rydberg states, which then emit fluorescence to produce singly excited, bound states. Inclusion of this process should bring calculations closer to agreement with recent measurements of dielectronic recombination.

n

and $\ensuremath{\ell}$ quantum numbers of the Rydberg electron. The nonstationary decay dynamics is studied by creating and manipulating Rydberg wave packets and by varying the laser pulse that drives the core excitation.

We have measured the linewidths of

{[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}

autoionizing Rydberg states of barium with principal quantum numbers ranging between

{n}_{2}=14

and

{n}_{2}=100

. Dramatic deviations of the autoionization rates from the normal ${n}_{2}^{*\ensuremath{-}3}$ scaling law have been observed. Whereas the

{[5{d}_{\frac{3}{2}}60{d}_{\frac{3}{2}}]}_{J=0}

level exhibits a linewidth $\ensuremath{\Gamma}$ (FWMH) as low as 6 MHz, higher (${n}_{2}\ensuremath{\approx}80$) members of this series are broadened up to 5 GHz. Autoionization is inhibited for principal quantum numbers ${n}_{2}\ensuremath{\approx}60$ because of configuration interaction between the

{[5{d}_{\frac{3}{2}}{n}_{2}{d}_{\frac{3}{2}}]}_{J=0}

and

{[5{d}_{\frac{5}{2}}{n}_{3}{d}_{\frac{5}{2}}]}_{J=0}

Rydberg series. This causes the state at

{n}_{2}=60

to be metastable.

We report the effects of static electric fields on the doubly excited

6{p}_{\frac{1}{2}}\mathrm{nl}

states of barium in the region

{n}^{*}=12

. Using a three-step laser excitation scheme we have measured the electric-field dependence of the positions and autoionization widths of the $6{p}_{\frac{1}{2}}\ensuremath{-}17s,16p,15d,12l (l=4\ensuremath{-}10),12f, \mathrm{and} 16s$ states at field values of up to 4.92 kV/cm. The photoexcitation spectra of the autoionizing states exhibit interference effects which are well understood and provide a better understanding of the character of these states in electric fields. The systematic study of the spectra and positions allows us to explain the field dependence of the autoionization widths in terms of electric-field mixing of the discrete portions of the auoionizing states. The relationship of these effects to dielectronic recombination rates of ions and electrons in plasma microfields is discussed.