Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physica Scripta

Saturation Effects in Resonant Three Photon Ionization of Potassium

S E Wheatley, Pierre Agostini, S N Dixit, M. D. Levenson

Published Sep 1, 1978• 5 citations
Publisher

Abstract

The intensity and polarization dependence of the ion production due to three quantum ionization was investigated in potassium. The energy of two of the photons was tuned into resonance with n 2 D levels for 4 < n < 22. The ratio of the ion signals produced with circular polarization to that found with linear polarization was significantly less than that predicted by a single rate approximation. The discrepancy is explained by the increased linewidth of the resonant 2 D level due to the ionization process itself. Single quantum photoionization cross sections for the excited levels calculated by means of quantum defect theory are shown to be consistent with the experimental results.

DOI
10.1088/0031-8949/18/3/006

Related papers

Saturation effects in multiphoton ionization

John A. Yeazell, Michelle S. Malcuit, Carlos R. Stroud +1 more

We have studied two-photon resonant three-photon ionization of atomic sodium vapor. A dye laser tuned to either the 4d or 5s two-photon allowed transition was used to excite the atom and a second more intense laser (λ = 7000 Å) was used for ionization. The ion yield was measured as a function of resonant laser intensity and detuning, the nonresonant laser intensity, and the temporal overlap of the exciting and ionizing laser pulses. We have found1 that at high laser intensities the photoionization yield decreases as the nonresonant laser intensity is increased. When tuned to the 5s level a value of ~−0.6 was obtained for the exponential index even with the resonant laser tuned to maximize the ion yield. A theoretical model including the effects of Stark shift of the ground state, power broadening of the intermediate level due to saturation of the two-photon transition and by rapid transitions to the ionization continuum was used to predict the experimental results. Good agreement between theory and experiment required the use of a photoionization cross section for the 5s level which was ~20 times greater than the accepted value. Results for photoionization from the 4d level are also presented.

Annual Meeting Optical Society of America•Jan 1, 1985•0 citations

Investigations of resonantly enhanced multiphoton ionizations of atomic mercury and potassium

Kelly Robert Lim Mah

Two investigations are reported on the application of resonantly enhanced multiphoton ionization (RMPI) to gaseous mixtures of an atomic vapor and a few Torr of argon. Photon fluxes large enough to ionize atoms by RMPI were produced by focussing down the light from a tunable pulsed dye laser. The irradiances generated were of the order of 500MWcm⁻². Ionization was detected by a voltage biased wire electrode that simply collected the photoelectrons either directly or after some gas multiplication. One investigation was the measurement of the dependence of RMPI processes in mercury on the polarization of the incident light for comparisons with theoretical calculations. The processes were four-photon resonant absorptions to either a ¹S₀ or ¹’³D₂ level followed by single photon ionization. Complete photoionization of all atoms excited to the resonant levels is established and the measured polarization dependences are found to agree with the calculated polarization dependence for the resonant excitation step of the RMPI process. Unexplained observations of the distortions in the polarization dependence of the ion yield and the absorption linewidth of the 6d ¹D₂ resonance are discussed. The second investigation was a study of the density dependent electric dipole forbidden two-photon resonant transition ²S → ²P in three-photon RMPI spectra of the Rydberg states of potassium. Stark interactions are shown to be unlikely and too weak. From the characteristics of the spectra, the excitation process is identified as a laser-assisted collision interaction.

•Jan 1, 2010•0 citations

Resonant three-photon ionization of potassium with circularly and linearly polarized light

Pierre Agostini, P. Bensoussan

We report observations of the ionization of atomic potassium by simultaneous absorption of three dye laser quanta. The laser wavelength is tuned through the two-photon resonances with the 6S1/2 and 4D3/2,5/2 states, and the dependence of the ionization probability on the laser wavelength is investigated for linearly and circularly polarized light. Our results are in agreement with the selection rules and theoretical estimates of the ionization probability.

Applied Physics Letters•Mar 1, 1974•28 citations

Resonant three-photon ionization of potassium with circularly and linearly polarized light

Pierre Agostini, P. Bensoussan

We report observations of the ionization of atomic potassium by simultaneous absorption of three dye laser quanta. The laser wavelength is tuned through the two‐photon resonances with the 6S1/2 and 4D3/2,5/2 states, and the dependence of the ionization probability on the laser wavelength is investigated for linearly and circularly polarized light. Our results are in agreement with the selection rules and theoretical estimates of the ionization probability.

IEEE Journal of Quantum Electronics•Sep 1, 1974•0 citations

Two-photon resonant three-photon ionization and atomic energy-pooling-induced ionization in potassium vapor

Changyong Li, Liantuan Xiao, Qian Li +2 more

The decay curves of potassium ion produced by Two-Photon Resonant Three-photon Ionization were measured. From the relation between ion current and multi-photon dynamic parameter, photo-ionization cross-section of 6S state of atomic potassium was determined. Potassium atom was ionized by Energy Pooling Effect when excited wavelength was 766.4 nm or 769.8 nm corresponding to the first excited state of potassium atom.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 8, 1999•0 citations

Resonant two-photon ionization of metastable helium and polarization dependency

Houston, Brian Harvey

The polarization dependency of relative cross-sections of the two-photon REMPI dipole transition (2$\sp1$S-3$\sp1$P) and quadrupole transition (2$\sp1$S-3$\sp1$D) is studied experimentally. Strict attention is paid to the measurement statistics, particularly to those associated with the ionizing laser beam. The cross section profiles are fitted to Voight functions that are generated from the measurement of experimental parameters. Ratios of the circular to linear polarization ion yields are also reported. These ratios are compared to theoretical predictions.

•Jan 1, 2023•0 citations
The intensity and polarization dependence of the ion production due to three quantum ionization was investigated in potassium. The energy of two of the photons was tuned into resonance with n 2 D levels for 4 < n < 22. The ratio of the ion signals produced with circular polarization to that found with linear polarization was significantly less than that predicted by a single rate approximation. The discrepancy is explained by the increased linewidth of the resonant 2 D level due to the ionization process itself. Single quantum photoionization cross sections for the excited levels calculated by means of quantum defect theory are shown to be consistent with the experimental results.
We have studied two-photon resonant three-photon ionization of atomic sodium vapor. A dye laser tuned to either the 4d or 5s two-photon allowed transition was used to excite the atom and a second more intense laser (λ = 7000 Å) was used for ionization. The ion yield was measured as a function of resonant laser intensity and detuning, the nonresonant laser intensity, and the temporal overlap of the exciting and ionizing laser pulses. We have found1 that at high laser intensities the photoionization yield decreases as the nonresonant laser intensity is increased. When tuned to the 5s level a value of ~−0.6 was obtained for the exponential index even with the resonant laser tuned to maximize the ion yield. A theoretical model including the effects of Stark shift of the ground state, power broadening of the intermediate level due to saturation of the two-photon transition and by rapid transitions to the ionization continuum was used to predict the experimental results. Good agreement between theory and experiment required the use of a photoionization cross section for the 5s level which was ~20 times greater than the accepted value. Results for photoionization from the 4d level are also presented.
Two investigations are reported on the application of resonantly enhanced multiphoton ionization (RMPI) to gaseous mixtures of an atomic vapor and a few Torr of argon. Photon fluxes large enough to ionize atoms by RMPI were produced by focussing down the light from a tunable pulsed dye laser. The irradiances generated were of the order of 500MWcm⁻². Ionization was detected by a voltage biased wire electrode that simply collected the photoelectrons either directly or after some gas multiplication. One investigation was the measurement of the dependence of RMPI processes in mercury on the polarization of the incident light for comparisons with theoretical calculations. The processes were four-photon resonant absorptions to either a ¹S₀ or ¹’³D₂ level followed by single photon ionization. Complete photoionization of all atoms excited to the resonant levels is established and the measured polarization dependences are found to agree with the calculated polarization dependence for the resonant excitation step of the RMPI process. Unexplained observations of the distortions in the polarization dependence of the ion yield and the absorption linewidth of the 6d ¹D₂ resonance are discussed. The second investigation was a study of the density dependent electric dipole forbidden two-photon resonant transition ²S → ²P in three-photon RMPI spectra of the Rydberg states of potassium. Stark interactions are shown to be unlikely and too weak. From the characteristics of the spectra, the excitation process is identified as a laser-assisted collision interaction.
The polarization dependency of relative cross-sections of the two-photon REMPI dipole transition (2$\sp1$S-3$\sp1$P) and quadrupole transition (2$\sp1$S-3$\sp1$D) is studied experimentally. Strict attention is paid to the measurement statistics, particularly to those associated with the ionizing laser beam. The cross section profiles are fitted to Voight functions that are generated from the measurement of experimental parameters. Ratios of the circular to linear polarization ion yields are also reported. These ratios are compared to theoretical predictions.