RIS Measurement of AC Stark Shifts and Photoionization Cross Sections in Calcium

We have measured the ac-Stark shift of the 14 D 5/2 Rydberg state of rubidium 87 in an optical dipole trap formed by a focused CO 2 laser. We found good quantitative agreement of the result with the model of a free electron experiencing a ponderomotive potential in the light field. In order to reproduce the observed spectra, we take into account the broadening of the Rydberg state due to photoionization. The extracted cross section is compatible with previous measurements on neighboring Rydberg states.We have measured the ac-Stark shift of the 14 D 5/2 Rydberg state of rubidium 87 in an optical dipole trap formed by a focused CO 2 laser. We found good quantitative agreement of the result with the model of a free electron experiencing a ponderomotive potential in the light field. In order to reproduce the observed spectra, we take into account the broadening of the Rydberg state due to photoionization. The extracted cross section is compatible with previous measurements on neighboring Rydberg states.

arXiv:1011.0837New Journal of PhysicsNov 2, 201012 citations

Study of photoionization and the Stark shift of levels by coherent-pulse spectroscopy methods

Rimantas Grigonis, K. N. Drabovish, N. M. Sinyavskii

Optics and SpectroscopyJan 1, 19871 citation

Resonant enhanced multiphoton ionization studies in atomic oxygen

S. N. Dixit, Deborah A. Levin, B. V. McKoy

In this paper we analyze two-photon-resonant three-photon ionization of atomic oxygen via the 2 ${\mathit{p}}^{3}$ ${(}^{4}$ S\ifmmode^\circ\else\textdegree\fi{}) ${\mathit{np}}^{3}$ ${\mathit{P}}_{0}$ ,1,2, and the 2 ${\mathit{p}}^{3}$ ${(}^{4}$ S\ifmmode^\circ\else\textdegree\fi{})nf $^{3}$ ${\mathit{F}}_{2}$ ,3,4 states. The various atomic parameters required for calculating the resonant enhanced multiphoton ionization (REMPI) probabilities are obtained using quantum-defect theory. The infinite sums over nonresonant states are truncated at a finite number of terms. Our calculated two-photon excitation cross sections agree well with the results of other recent calculations and of experimental measurements. The photoionization cross section is calculated for various electron kinetic energies. The REMPI dynamics is analyzed by solving the density-matrix equations. This framework consistently takes into account the effects of saturation and ac Stark shifts. REMPI probability is seen to be quite sensitive to the initial detuning, the intensity, and the particular resonant state accessed. The photoionization cross sections also imply that due to the rapid falloff of the cross section, two-color REMPI schemes with a lower-frequency ionizing photon would increase the effective REMPI probability.In this paper we analyze two-photon-resonant three-photon ionization of atomic oxygen via the 2${\mathit{p}}^{3}$${(}^{4}$S\ifmmode^\circ\else\textdegree\fi{})${\mathit{np}}^{3}$${\mathit{P}}_{0}$,1,2, and the 2${\mathit{p}}^{3}$${(}^{4}$S\ifmmode^\circ\else\textdegree\fi{})nf $^{3}$${\mathit{F}}_{2}$,3,4 states. The various atomic parameters required for calculating the resonant enhanced multiphoton ionization (REMPI) probabilities are obtained using quantum-defect theory. The infinite sums over nonresonant states are truncated at a finite number of terms. Our calculated two-photon excitation cross sections agree well with the results of other recent calculations and of experimental measurements. The photoionization cross section is calculated for various electron kinetic energies. The REMPI dynamics is analyzed by solving the density-matrix equations. This framework consistently takes into account the effects of saturation and ac Stark shifts. REMPI probability is seen to be quite sensitive to the initial detuning, the intensity, and the particular resonant state accessed. The photoionization cross sections also imply that due to the rapid falloff of the cross section, two-color REMPI schemes with a lower-frequency ionizing photon would increase the effective REMPI probability.

Physical Review AJun 1, 198821 citations

Stark broadening of calcium ion resonance lines

J. S. Hildum, J. Cooper

Physics Letters AAug 1, 197121 citations

In this paper we analyze two-photon-resonant three-photon ionization of atomic oxygen via the 2

{\mathit{p}}^{3}

{(}^{4}

S\ifmmode^\circ\else\textdegree\fi{})

{\mathit{np}}^{3}

{\mathit{P}}_{0}

,1,2, and the 2

{\mathit{p}}^{3}

{(}^{4}

S\ifmmode^\circ\else\textdegree\fi{})nf

^{3}

{\mathit{F}}_{2}

,3,4 states. The various atomic parameters required for calculating the resonant enhanced multiphoton ionization (REMPI) probabilities are obtained using quantum-defect theory. The infinite sums over nonresonant states are truncated at a finite number of terms. Our calculated two-photon excitation cross sections agree well with the results of other recent calculations and of experimental measurements. The photoionization cross section is calculated for various electron kinetic energies. The REMPI dynamics is analyzed by solving the density-matrix equations. This framework consistently takes into account the effects of saturation and ac Stark shifts. REMPI probability is seen to be quite sensitive to the initial detuning, the intensity, and the particular resonant state accessed. The photoionization cross sections also imply that due to the rapid falloff of the cross section, two-color REMPI schemes with a lower-frequency ionizing photon would increase the effective REMPI probability.