Photoionization cross sections for excited states of argon and krypton

Hyman, H.

doi:10.1063/1.89481

Cited by 46 publications

(11 citation statements)

References 12 publications

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“…In the circumstances prevailing in this experiment, the photo-ionization rate from the metastable state is negligible [31], and the low gas pressures (0.05 mbar) mean that the collisional rates are negligible in comparison to optical transition rates [16]. In those conditions, the 760 nm LIF is directly proportional to the total metastable population produced by a laser pulse.…”

Section: Apparatus and Proceduresmentioning

confidence: 91%

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Laser-Based Metastable Krypton Generation

et al. 2018

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We demonstrate the generation of metastable krypton in the long-lived 1s^{5} state using laser excitation. The atoms are excited through a two-photon absorption process into the 2p^{6} state using a pulsed optical parametric oscillator laser operating near 215 nm, after which the atoms decay quickly into the metastable state with a branching ratio of 75%. The interaction dynamics are modeled using density matrix formalism and, by combining this with experimental observations, we are able to calculate photoionization and two-photon absorption cross sections. When compared to traditional approaches to metastable production, this approach shows great potential for high-density metastable krypton production with minimal heating of the sample. Here, we show metastable production efficiencies of up to 2% per pulse. The new experimental results gained here, when combined with the density matrix model we have developed, suggest that fractional efficiencies up to 30% are possible under optimal conditions.

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Section: Apparatus and Proceduresmentioning

confidence: 91%

“…where we note that the photo-ionization cross-section from the 1s 5 state σ mi is less than 3 % of that from the 2p 6 state σ ei [31]. We have thus neglected the former in the calculation as it does not significantly modify the metastable population.…”

Section: Theory and Analysismentioning

confidence: 99%

Laser-Based Metastable Krypton Generation

et al. 2018

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“…electrons in excited rare-gas atoms with those in the respective alkali atoms has been reproduced in calculations of excited states with = 0[261,262,[326][327][328][329][330]], = 1[261,296,326,[331][332][333], and = 2[261]. In many of these calculations, however, electron correlation, relativistic effects and the open-shell structure of the rare gas ion core were ignored.In a single configuration description, photoionization from the metastable (m+1)s J = 2 level (J + = 3/2 core) and from the (m + 1)s J = 0 level (J + = 1/2) only involve the respective core-conserving "major" transitions, i.e., those leading to the formation of only Rg + ( 2 P 3/2 ) ions from J = 2 and only Rg + ( 2 P 1/2 ) ions from J = 0.Correlation effects in the initial and final states, however, modify this simple picture considerably and result in the observation of the core-changing "minor" transitions.…”

mentioning

confidence: 99%

Photoionization dynamics of excited Ne, Ar, Kr and Xe atoms near threshold

Sukhorukov¹,

Petrov²,

Schäfer³

et al. 2012

J. Phys. B: At. Mol. Opt. Phys.

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A review of experimental and theoretical studies of the threshold photoionization of the heavier rare-gas atoms is presented, with particular emphasis on the autoionization resonances in the spectral region between the lowest two ionization thresholds (mp 5 2 P 3/2 and mp 5 2 P 1/2 , with m = 2, 3, 4, and 5 for Ne, Ar, Kr, and Xe, respectively). Observed trends in the positions, widths, and shapes of the autoionization resonances in dependence of the atomic number, the principal quantum number n, the orbital angular momentum quantum number and further quantum numbers such as K, J and F specifying the fine-and hyperfine-structure levels, are summarized and discussed in the light of ab initio and multichannel quantum defect theory calculations. The dependence of the photoionization spectra on the initially prepared neutral state, e.g. the 1 S 0 ground state, the mp 5 (m + 1)s 3 P 2 and mp 5 (m + 1)s 3 P 0 metastable levels and other states prepared from the ground or metastable levels in single-and multiphoton processes, are also discussed, including results on the photoionization of aligned and oriented samples and on photoelectron angular distributions. The effects of various approximations in the theoretical treatment of photoionization in these systems are analysed. The very large and at first sight discouraging diversity of observed phenomena and the numerous anomalies in spectral structures associated with the threshold ionization of the rare-gas atoms can be described in terms of a limited set of interactions and dynamical processes. Examples are provided illustrating characteristic aspects of the photoionization, and sets of recommended parameters describing the energy-level structure and photoionization dynamics of the rare-gas atoms are presented which were extracted in a critical analysis of the very large body of experimental and theoretical data available on these systems in the literature.

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“…is the rate of 1-photon ionization of excited Kr atoms, σ a ≈4.5x10 −22 m 2 is 1-photon ionization cross section of excited Kr, 33 W Σ = W i is the summarized effect given by Eq. (5) and N Kr−0 = P Kr /k B T is the initial density of Kr.…”

Section: Aip Advances 6 095018 (2016)mentioning

confidence: 99%

Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

et al. 2016

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We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

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Photoionization cross sections for excited states of argon and krypton

Cited by 46 publications

References 12 publications

Laser-Based Metastable Krypton Generation

Laser-Based Metastable Krypton Generation

Photoionization dynamics of excited Ne, Ar, Kr and Xe atoms near threshold

Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

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