Physical Review Letters

Observation of resonant excess-photon detachment via a window resonance in the cesium negative ion

Henrik Stapelfeldt, Harold K. Haugen

Published Nov 2, 1992• 20 citations

Abstract

Efficient excess-photon detachment to lowest nonvanishing order is observed with long (\ensuremath{\sim}0.7 ns) optical pulses and intensities of \ensuremath{\le}6\ifmmode\times\else\texttimes\fi{}${10}^{9}$ W/${\mathrm{cm}}^{2}$. A Feshbach (``window'') resonance in ${\mathrm{Cs}}^{\mathrm{\ensuremath{-}}}$ suppresses single-photon detachment, while simultaneously enhancing the probability of absorption of one or more excess photons. The perspectives for future spectroscopic excess-photon detachment and studies of direct two-electron multiphoton detachment are briefly discussed.

DOI: 10.1103/physrevlett.69.2638

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Physical Review Letters

Observation of resonant excess-photon detachment via a window resonance in the cesium negative ion

Henrik Stapelfeldt, Harold K. Haugen

Published Nov 2, 1992• 20 citations

Publisher

Abstract

Efficient excess-photon detachment to lowest nonvanishing order is observed with long (\ensuremath{\sim}0.7 ns) optical pulses and intensities of \ensuremath{\le}6\ifmmode\times\else\texttimes\fi{}

{10}^{9}

{\mathrm{cm}}^{2}

. A Feshbach (``window'') resonance in

{\mathrm{Cs}}^{\mathrm{\ensuremath{-}}}

suppresses single-photon detachment, while simultaneously enhancing the probability of absorption of one or more excess photons. The perspectives for future spectroscopic excess-photon detachment and studies of direct two-electron multiphoton detachment are briefly discussed.

DOI: 10.1103/physrevlett.69.2638

Related papers

Observation of Resonant Excess Photon Detachment Via a Window Resonance in the Negative Cesium Ion

Henrick Stepelfeldt, Péter Balling, Harold K. Haugen

NATO ASI series. Series B : PhysicsJan 1, 19931 citation

Resonant Two-Photon Detachment through the Lowest SingletDState in H−

A. Stintz, Xin Miao Zhao, Charlie E. M. Strauss +4 more

We report the measurement of the two-photon detachment spectrum of the $^{1}D^{e}$ resonance of ${\mathrm{H}}^{\ensuremath{-}}$ just below the $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$ threshold. The excess photon detachment resonance fits a Fano profile with energy 10.872(2) eV (relative to ${\mathrm{H}}^{\ensuremath{-}}$ ground state), a width of 0.0105(10) eV, and a shape parameter of $\ensuremath{-}8(2)$. To our knowledge, this describes the first time direct multiphoton excitation of a resonance has been observed in any negative atomic ion.We report the measurement of the two-photon detachment spectrum of the $^{1}D^{e}$ resonance of ${\mathrm{H}}^{\ensuremath{-}}$ just below the $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$ threshold. The excess photon detachment resonance fits a Fano profile with energy 10.872(2) eV (relative to ${\mathrm{H}}^{\ensuremath{-}}$ ground state), a width of 0.0105(10) eV, and a shape parameter of $\ensuremath{-}8(2)$. To our knowledge, this describes the first time direct multiphoton excitation of a resonance has been observed in any negative atomic ion.

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Daniel Proulx, Robin Shakeshaft

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Henrik Stapelfeldt, Philip Trøst Kristensen, Ulric B. Ljungblad +2 more

We have performed an experimental study of the atomic system ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$, for which the ground state 5 ${\mathit{s}}^{2}$ is coupled to the autoionizing state 5${\mathit{p}}_{1/2}$6s by means of a strong resonant laser field. The investigations are based on irradiation of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ with intense (I\ensuremath{\le}1.5\ifmmode\times\else\texttimes\fi{} ${10}^{10}$ W/ ${\mathrm{cm}}^{2}$ ) laser pulses of duration \ensuremath{\sim}1 ns. Single-photon detachment of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ is suppressed due to the Fano interference between transitions directly to the continuum and transitions via the autoionizing state. In contrast, two-photon absorption is at the same time resonantly enhanced since no such destructive interference is present in this process. These observations constitute experimental evidence of general features predicted from theoretical considerations of autoionizing states in strong laser fields. Furthermore, we discuss the role of autoionizing states in multiphoton double-ionization processes. Electron spectroscopy has been used to show that double ionization of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ primarily is the result of a sequential removal of the two electrons via an excited Rb state. The perspectives for direct two-electron ionization in negative ions are briefly discussed.We have performed an experimental study of the atomic system ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$, for which the ground state 5${\mathit{s}}^{2}$ is coupled to the autoionizing state 5${\mathit{p}}_{1/2}$6s by means of a strong resonant laser field. The investigations are based on irradiation of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ with intense (I\ensuremath{\le}1.5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ W/${\mathrm{cm}}^{2}$) laser pulses of duration \ensuremath{\sim}1 ns. Single-photon detachment of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ is suppressed due to the Fano interference between transitions directly to the continuum and transitions via the autoionizing state. In contrast, two-photon absorption is at the same time resonantly enhanced since no such destructive interference is present in this process. These observations constitute experimental evidence of general features predicted from theoretical considerations of autoionizing states in strong laser fields. Furthermore, we discuss the role of autoionizing states in multiphoton double-ionization processes. Electron spectroscopy has been used to show that double ionization of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ primarily is the result of a sequential removal of the two electrons via an excited Rb state. The perspectives for direct two-electron ionization in negative ions are briefly discussed.

Physical Review AAug 1, 199417 citations

Efficient excess-photon detachment to lowest nonvanishing order is observed with long (\ensuremath{\sim}0.7 ns) optical pulses and intensities of \ensuremath{\le}6\ifmmode\times\else\texttimes\fi{}

{10}^{9}

{\mathrm{cm}}^{2}

. A Feshbach (``window'') resonance in

{\mathrm{Cs}}^{\mathrm{\ensuremath{-}}}

We report the measurement of the two-photon detachment spectrum of the

^{1}D^{e}

resonance of ${\mathrm{H}}^{\ensuremath{-}}$ just below the

n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2

threshold. The excess photon detachment resonance fits a Fano profile with energy 10.872(2) eV (relative to ${\mathrm{H}}^{\ensuremath{-}}$ ground state), a width of 0.0105(10) eV, and a shape parameter of $\ensuremath{-}8(2)$. To our knowledge, this describes the first time direct multiphoton excitation of a resonance has been observed in any negative atomic ion.

{\mathit{p}}^{5}

^{2}

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

and

^{2}

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

fine-structure states. The fine-structure splitting is determined to be 5004.7\ifmmode\pm\else\textpm\fi{}0.2 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, which represents a 25-fold improvement over earlier measurements. The possibilities for extended spectroscopic measurements, as well as general perspectives for multiphoton experiments at high intensities, are briefly discussed.

^{1}

{\mathit{S}}^{\mathit{e}}

and

^{1}

{\mathit{D}}^{\mathit{e}}

Feshbach resonances below the n=2 and n=3 excitation thresholds of H; these resonances lie in the ``excess-photon detachment'' regime, where one photon is already sufficient to detach the electron.

We have performed an experimental study of the atomic system ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$, for which the ground state 5

{\mathit{s}}^{2}

is coupled to the autoionizing state 5${\mathit{p}}_{1/2}$6s by means of a strong resonant laser field. The investigations are based on irradiation of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ with intense (I\ensuremath{\le}1.5\ifmmode\times\else\texttimes\fi{}

{10}^{10}

{\mathrm{cm}}^{2}

) laser pulses of duration \ensuremath{\sim}1 ns. Single-photon detachment of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ is suppressed due to the Fano interference between transitions directly to the continuum and transitions via the autoionizing state. In contrast, two-photon absorption is at the same time resonantly enhanced since no such destructive interference is present in this process. These observations constitute experimental evidence of general features predicted from theoretical considerations of autoionizing states in strong laser fields. Furthermore, we discuss the role of autoionizing states in multiphoton double-ionization processes. Electron spectroscopy has been used to show that double ionization of ${\mathrm{Rb}}^{\mathrm{\ensuremath{-}}}$ primarily is the result of a sequential removal of the two electrons via an excited Rb state. The perspectives for direct two-electron ionization in negative ions are briefly discussed.