Physical Review Letters

Resonant Multiphoton Ionization of Krypton with a Single-Mode Laser

Pierre Agostini, C. Lecompte

Published May 10, 1976• 8 citations

Abstract

Multiphoton ionization of krypton has been experimentally investigated for the first time with a single-mode tunable ${\mathrm{Nd}}^{3+}$: glass laser producing an electric field of $E=8\ifmmode\times\else\texttimes\fi{}{10}^{7}$ V/cm. In the range 10 585 \AA{} to 10 605 \AA{}, two resonances have been found, shifted towards the high-energy side from the nearest states $5d{[\frac{1}{2}]}_{1}$ and $4{d}^{\ensuremath{'}}{[\frac{5}{2}]}_{3}$ by 39.5 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 42 ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively. Far from resonances, the dependence of the ionization rate on the laser intensity agrees with the lowest-order perturbation-theory prediction.

DOI: 10.1103/physrevlett.36.1131

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Resonance shifts in the multiphoton ionization of cesium atoms

J. Morellec, Didier Normand, G. Petite

Physical Review AJul 1, 1976107 citations

Contrasted behaviour of Stark-induced resonances in multiphoton ionization of krypton

E. Mével, P. Breger, Rusty P. Trainham +5 more

Journal of Physics B Atomic Molecular and Optical PhysicsSep 14, 199219 citations

Resonant multiphoton ionization of neon by a ruby laser

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The consistent relativistic energy approach to atoms in a strong realistic laser field, based on the Gell-Mann and Low S-matrix formalism, is applied in the study of resonant multiphoton ionization of krypton by intense uv laser radiation and for the computation of the resonance shift and width in krypton. The approach to the treatment of the multiphoton resonances in nuclei is outlined for the 57 Fe nucleus.

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Physical Review Letters

Resonant Multiphoton Ionization of Krypton with a Single-Mode Laser

Pierre Agostini, C. Lecompte

Published May 10, 1976• 8 citations

Publisher

Abstract

Multiphoton ionization of krypton has been experimentally investigated for the first time with a single-mode tunable

{\mathrm{Nd}}^{3+}

: glass laser producing an electric field of

E=8\ifmmode\times\else\texttimes\fi{}{10}^{7}

V/cm. In the range 10 585 \AA{} to 10 605 \AA{}, two resonances have been found, shifted towards the high-energy side from the nearest states

5d{[\frac{1}{2}]}_{1}

and

4{d}^{\ensuremath{'}}{[\frac{5}{2}]}_{3}

by 39.5

{\mathrm{cm}}^{\ensuremath{-}1}

and 42

{\mathrm{cm}}^{\ensuremath{-}1}

, respectively. Far from resonances, the dependence of the ionization rate on the laser intensity agrees with the lowest-order perturbation-theory prediction.

DOI: 10.1103/physrevlett.36.1131

Related papers

Resonance shifts in the multiphoton ionization of cesium atoms

J. Morellec, Didier Normand, G. Petite

This work reports the multiphoton ionization of cesium atoms, via resonance with the $6F$ level, by interaction with a single transverse and longitudinal mode neodymium-glass laser beam. At a low rate of ion production, when the laser frequency is tuned through resonance, the laser intensity necessary to create a constant number of ions passes through a minimum, as expected, for a three-photon energy equal to the unperturbed $6S\ensuremath{\rightarrow}6F$ transition energy. But for a higher ionization rate, involving larger laser intensities, a departure from expectation is observed which is interpreted as a consequence of an energy shift of the transition. The level shifts are demonstrated in another way by their strong effect on the experimental order of nonlinearity of the interaction, ${K}_{\mathrm{expt}}$ . A sharp variation of ${K}_{\mathrm{expt}}$ is observed when the energy shift of the $6S\ensuremath{\rightarrow}6F$ transition exactly compensates the wavelength detuning of the laser. The latter method gives shift values which are found to be independent of the large variations of the interaction volume under conditions of resonance. Both methods give a linear dependence of the shifts on the laser intensity. Identification of these shifts with energy shifts of the $6S\ensuremath{\rightarrow}6F$ transition is subject to theoretical reservations and needs further experimentation.This work reports the multiphoton ionization of cesium atoms, via resonance with the $6F$ level, by interaction with a single transverse and longitudinal mode neodymium-glass laser beam. At a low rate of ion production, when the laser frequency is tuned through resonance, the laser intensity necessary to create a constant number of ions passes through a minimum, as expected, for a three-photon energy equal to the unperturbed $6S\ensuremath{\rightarrow}6F$ transition energy. But for a higher ionization rate, involving larger laser intensities, a departure from expectation is observed which is interpreted as a consequence of an energy shift of the transition. The level shifts are demonstrated in another way by their strong effect on the experimental order of nonlinearity of the interaction, ${K}_{\mathrm{expt}}$. A sharp variation of ${K}_{\mathrm{expt}}$ is observed when the energy shift of the $6S\ensuremath{\rightarrow}6F$ transition exactly compensates the wavelength detuning of the laser. The latter method gives shift values which are found to be independent of the large variations of the interaction volume under conditions of resonance. Both methods give a linear dependence of the shifts on the laser intensity. Identification of these shifts with energy shifts of the $6S\ensuremath{\rightarrow}6F$ transition is subject to theoretical reservations and needs further experimentation.

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Contrasted behaviour of Stark-induced resonances in multiphoton ionization of krypton

E. Mével, P. Breger, Rusty P. Trainham +5 more

Electron energy spectra from multiphoton ionization of krypton with 617 nm, 70 fs pulses have been recorded over a large intensity range. Near the appearance intensity, the spectra display Stark-induced resonances with s and d states. Up to about 8*10 13 W cm -2 , the spectra broaden and the structures are progressively washed out. Above this intensity, a strong resonance emerges, corresponding to the 4f state for which the static detuning is 2.94 eV, a value larger than the photon energy. The influence of a large static detuning and populations of excited states with shifts different from the threshold shift are discussed.Electron energy spectra from multiphoton ionization of krypton with 617 nm, 70 fs pulses have been recorded over a large intensity range. Near the appearance intensity, the spectra display Stark-induced resonances with s and d states. Up to about 8*10 13 W cm -2 , the spectra broaden and the structures are progressively washed out. Above this intensity, a strong resonance emerges, corresponding to the 4f state for which the static detuning is 2.94 eV, a value larger than the photon energy. The influence of a large static detuning and populations of excited states with shifts different from the threshold shift are discussed.

Journal of Physics B Atomic Molecular and Optical PhysicsSep 14, 199219 citations

Resonant multiphoton ionization of neon by a ruby laser

R. Benattar, G. Sultan

We report resonant multiphoton ionization in neon. The study of the interaction volume shows that the size of the focused region depends on the laser power, order of interaction, and energy of photon. Thus we have chosen a resonant approach. The results show a discrepancy of 6 cm−1 between the experimental multiphoton resonance and the theoretically predicted one. We explain this discrepancy by the perturbative effect of the intense electromagnetic field of the laser on the resonant atomic level 11p [3/2]1,2 of neon.We report resonant multiphoton ionization in neon. The study of the interaction volume shows that the size of the focused region depends on the laser power, order of interaction, and energy of photon. Thus we have chosen a resonant approach. The results show a discrepancy of 6 cm−1 between the experimental multiphoton resonance and the theoretically predicted one. We explain this discrepancy by the perturbative effect of the intense electromagnetic field of the laser on the resonant atomic level 11p [3/2]1,2 of neon.

Journal of Applied PhysicsOct 1, 19744 citations

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Journal of Physics Conference SeriesNov 24, 201453 citations

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І. І. Бондар, В. В. Суран, Denys I. Bondar

Despite inherently complex multiphoton dynamics, our observations show that Ba double ionization with an infrared laser (8800--8920 cm${}^{\ensuremath{-}1}$) resembles a single-photon process; namely, its probability is proportional to the laser intensity. In this regime, single-electron ionization is due to a four-photon resonant transition through the highly perturbed state $6{p}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{D}_{2}$ , whereas double ionization is realized by the two-electron mechanism. Furthermore, we argue that these conclusions are valid for other alkaline-earth-metal atoms and other parameters of laser radiation.Despite inherently complex multiphoton dynamics, our observations show that Ba double ionization with an infrared laser (8800--8920 cm${}^{\ensuremath{-}1}$) resembles a single-photon process; namely, its probability is proportional to the laser intensity. In this regime, single-electron ionization is due to a four-photon resonant transition through the highly perturbed state $6{p}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{D}_{2}$, whereas double ionization is realized by the two-electron mechanism. Furthermore, we argue that these conclusions are valid for other alkaline-earth-metal atoms and other parameters of laser radiation.

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Resonant multiphoton ionization of caesium atoms

G. Petite, J. Morellec, Didier Normand

This paper studies the resonant multiphoton ionization (RMPI) phenomenon, in the case of caesium atoms interacting with the intense field of a neodymium-Glass laser. In the first part, we present a recent theory of RMPI, in a simplified form in order to obtain the main informations on the physics of RMPI. Then we present two experiments of RMPI : four-photon ionization of the caesium atom in its ground state, with a three-photon resonance on the 6F level and three-photon ionization of the caesium atom is its 62P3/2 state with a two-photon resonance on the 12F level. In the first experiment, the internal structure of the resonant transition is resolved, enabling us to point out and analyse the important effect of pulse shapes and focusing conditions on our experimental results, which are discussed in detail. We also give some new interpretations of results published previously [1]. In the second experiment, we measure the 12F fine structure — which is found to be (0.016 ± 0.008) cm-1 — and show that we have reached the limits imposed by the Doppler effect. These experimental results are in good agreement with the theoretical predictions suggesting that the physical picture given of RMPI by recent works on this subject is satisfactory.This paper studies the resonant multiphoton ionization (RMPI) phenomenon, in the case of caesium atoms interacting with the intense field of a neodymium-Glass laser. In the first part, we present a recent theory of RMPI, in a simplified form in order to obtain the main informations on the physics of RMPI. Then we present two experiments of RMPI : four-photon ionization of the caesium atom in its ground state, with a three-photon resonance on the 6F level and three-photon ionization of the caesium atom is its 62P3/2 state with a two-photon resonance on the 12F level. In the first experiment, the internal structure of the resonant transition is resolved, enabling us to point out and analyse the important effect of pulse shapes and focusing conditions on our experimental results, which are discussed in detail. We also give some new interpretations of results published previously [1]. In the second experiment, we measure the 12F fine structure — which is found to be (0.016 ± 0.008) cm-1 — and show that we have reached the limits imposed by the Doppler effect. These experimental results are in good agreement with the theoretical predictions suggesting that the physical picture given of RMPI by recent works on this subject is satisfactory.

Journal de physiqueJan 1, 197954 citations

Multiphoton ionization of krypton has been experimentally investigated for the first time with a single-mode tunable

{\mathrm{Nd}}^{3+}

: glass laser producing an electric field of

E=8\ifmmode\times\else\texttimes\fi{}{10}^{7}

V/cm. In the range 10 585 \AA{} to 10 605 \AA{}, two resonances have been found, shifted towards the high-energy side from the nearest states

5d{[\frac{1}{2}]}_{1}

and

4{d}^{\ensuremath{'}}{[\frac{5}{2}]}_{3}

by 39.5

{\mathrm{cm}}^{\ensuremath{-}1}

and 42

{\mathrm{cm}}^{\ensuremath{-}1}

, respectively. Far from resonances, the dependence of the ionization rate on the laser intensity agrees with the lowest-order perturbation-theory prediction.

This work reports the multiphoton ionization of cesium atoms, via resonance with the

6F

level, by interaction with a single transverse and longitudinal mode neodymium-glass laser beam. At a low rate of ion production, when the laser frequency is tuned through resonance, the laser intensity necessary to create a constant number of ions passes through a minimum, as expected, for a three-photon energy equal to the unperturbed $6S\ensuremath{\rightarrow}6F$ transition energy. But for a higher ionization rate, involving larger laser intensities, a departure from expectation is observed which is interpreted as a consequence of an energy shift of the transition. The level shifts are demonstrated in another way by their strong effect on the experimental order of nonlinearity of the interaction,

{K}_{\mathrm{expt}}

. A sharp variation of

{K}_{\mathrm{expt}}

is observed when the energy shift of the $6S\ensuremath{\rightarrow}6F$ transition exactly compensates the wavelength detuning of the laser. The latter method gives shift values which are found to be independent of the large variations of the interaction volume under conditions of resonance. Both methods give a linear dependence of the shifts on the laser intensity. Identification of these shifts with energy shifts of the $6S\ensuremath{\rightarrow}6F$ transition is subject to theoretical reservations and needs further experimentation.

6{p}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{D}_{2}

, whereas double ionization is realized by the two-electron mechanism. Furthermore, we argue that these conclusions are valid for other alkaline-earth-metal atoms and other parameters of laser radiation.