Autoionization of Rydberg states with large angular momentum: Application to alkaline-earth atoms

Poirier, Michel

doi:10.1103/physreva.38.3484

Cited by 51 publications

(43 citation statements)

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“…3. Compared to the low rates of the bound electrons the photoionization rate falls off like (E free /E bound ) 7/2 [11] and the Auger decay rate roughly like (E free /E bound ) 3/2 [20]. Due to this scaling the rates are reduced during the pulse by a factors of about 5 and 20, respectively.…”

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confidence: 93%

Ionization of Clusters in Strong X-Ray Laser Pulses

Saalmann

Rost

2002

Phys. Rev. Lett.

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The effect of intense X-ray laser interaction on argon clusters is studied theoretically with a mixed quantum/classical approach. In comparison to a single atom we find that ionization of the cluster is suppressed, which is in striking contrast to the observed behavior of rare-gas clusters in intense optical laser pulses. We have identified two effects responsible for this phenomenon: A high space charge of the cluster in combination with a small quiver amplitude and delocalization of electrons in the cluster. We elucidate their impact for different field strengths and cluster sizes. PACS numbers: 33.90.+h, 32.80.Hd, 36.40.Wa, 41.60.Cr The advent of femtosecond laser pulses has triggered numerous activities in the field of laser-matter interaction. In particular novel, non-linear processes in atoms induced by the available high intense fields from these ultrashort pulses have been a challenge for experiment and theory [1]. To understand more generally the energy transfer from intense laser light to matter, complex targets like atomic clusters have been studied [2,3,4,5]. These experiments received considerable attention due to the observed dramatic effects like emission of very fast ions [2] and electrons [3] or the production of coherent X-ray radiation [4]. So far such studies are almost exclusively restricted to visible or infrared wavelengths [6]. The new X-ray free electron laser (xfel) sources, under construction at DESY in Hamburg [7] and at the LCLS in Stanford [8], will change this situation. They can deliver intense laser pulses at high frequencies (from VUV to hard X-ray) and thus open a new regime of strong-field atomic physics.Here we present theoretical investigations of X-ray (frequencyhω = 350 eV, i. e. wavelength λ ≈ 3.5 nm) laser interaction with argon clusters at intensities of I ≈ 3.5·10 14 . . . 3.5·10 18 W/cm 2 . In this laser regime the interaction is notably different from long-wavelength pulses which is evident from the ponderomotive energy E pond ∼ I/ω 2 . It represents the average kinetic energy of a free electron in a laser field, while ∆x ∼ √ I/ω 2 is the quiver amplitude of the electron, i. e., the spatial excursion in the laser field. For the given laser parameters one finds E pond ≈ 0.4 meV . . . 4 eV, vastly different from E pond ≈ 20 eV . . . 200 keV for a 780-nm-laser at the same intensities. The small ponderomotive energy has two important consequences: (i) Despite the high intensities the laser-atom interaction is of non-relativistic and perturbative nature. The latter is also clear from the so-called Keldysh parameter γ which gives the ratio between the tunneling time and the laser period [9] and can be rewritten in terms of the binding energy E bind and the ponderomotive energy E pond as γ = (E bind /2E pond ) 1/2 . For the L and M -shells of argon with E bind = 326, 249, 29.3, 15.8 eV we always find γ > 1 and for the inner shells even γ ≫ 1. Obviously the laser period is far too small for field-or tunnel-ionization. Rather, ionization is due to single-photon absorption....

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confidence: 93%

Ionization of Clusters in Strong X-Ray Laser Pulses

Saalmann

Rost

2002

Phys. Rev. Lett.

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“…In the experiment we use a well-collimated atomic beam, in which metastable states of the 5d configuration are populated by running a DC discharge between the bariumfilled tantalum oven and a heating wire. A fraction of [1] First excitation in a homogeneous electric field; [2] Field-free inner-core excitation after Stark switching; [3] Field-ionisation of singly-excited atoms for locking the first laser to the atomic transition. (E.M."electron multiplier) about 10\ of the atoms is transferred to the metastable 5d G state at 24696.278 cm\.…”

Section: Methodsmentioning

confidence: 99%

“…With these assumptions the autoionisation rate for an atom in a ( jl ) K-coupled doubly-excited n l n l state ionising into a n l l continuum may be expressed as [3]:…”

Section: P 3 2 40h Statesmentioning

confidence: 99%

“…The studies on doubly-excited Rydberg states of alkaline-earth atoms partly focus on the understanding of autoionisation processes [1][2][3][4][5][6] and partly on effects of correlated electron motion [7][8][9][10][11]. High angular momentum Rydberg states received special attention as in this case the Rydberg electron does not penetrate the orbit of the inner (excited) electron, thus reducing autoionisation rates.…”

Section: Introductionmentioning

confidence: 99%

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CW laser spectroscopy of autoionising 6 p 3/2 nl states of Barium

Kuik

Vassen

Hogervorst

1996

Zeitschrift f�r Physik D Atoms, Molecules and Clusters

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6pnl states of Ba with l55, excited with two narrowband, tunable CW lasers have been studied. In the first excitation step 6snl states were populated from metastable states of the 5d configuration: to 6s40h (l"5) states in the absence, and to parabolic 6pnk (n"30, 35, 40) states in the presence of an electric field. The atomic motion was used to adiabatically reduce this field to zero before applying the second excitation step to high-l 6p nl states (Stark-switching). A slow decrease in the autoionisation rate for increasing value of l and, in case of 6pnh, a dependence on the fine-structure state was measured. The narrowest autoionisation linewidth observed is 113(11) MHz, relatively close to the 20 MHz linewidth corresponding to the radiative lifetime of the 6p state of the Ba>-ion.

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“…The contributions to the static polarizability of highly Rydberg states (n > 13) and from the continuum have been obtained from perturbative calculation using an effective oscillator strength averaged over the continuum. 13 Our approach 14 is to consider the reverse process in Equation (1) Fig. 1, the trajectories in the complex plane of the quasi-energies belonging to ∆ n = 2 transition in CIII corresponding to 1s 2 2p7s ( 1 P 0 ) and 1s 2 2s5s ( 1 S e ) states in Eq.…”

Section: +mentioning

confidence: 99%

Static and dynamic polarizability for C2+ in Rydberg states

Stǎncǎlie

2015

AIP Advances

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This work presents results from a non-perturbative calculation of dynamic polarizability of C III ions in 1s 2 2sns ( 1 S e ) Rydberg states. We employ a two-state model for dressed atomic states to investigate the effect of the frequency-dependent polarizability of optically dressed 1s 2 2sns( 1 S e ) states (n = 5 − 12) on transitions to nearby states (1s 2 2pns( 1 P 1 o )). Our model calculation results indicate that the resonance structure of the polarizabilities is entirely captured by the transition terms whereas the free electron polarizability only provides a smooth background. The resonance structure is evident in the plots and the widths increase with increasing principal quantum number. This work refers to highly excited 1s 2 2sns ( 1 S) Rydberg states, embedded in the electric dipole field of the 2s -2p core transition in Li-like C 3+ ion. The contributions of the individual transitions to the static polarizabilities of these Rydberg states are obtained from the use of the sum-over-state method. To this aim, both the C 2+ ground state and the C 3+ target state energies have been carefully calculated based on the configuration interactions method implemented in the General-purpose Relativistic Atomic Structure Package. Agreement is reasonably good with existing data wherever available. These results are believed to be the first such values for this system and will be important for ionic spectroscopy and plasma diagnostics. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

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Autoionization of Rydberg states with large angular momentum: Application to alkaline-earth atoms

Cited by 51 publications

References 38 publications

Ionization of Clusters in Strong X-Ray Laser Pulses

Ionization of Clusters in Strong X-Ray Laser Pulses

CW laser spectroscopy of autoionising 6 p 3/2 nl states of Barium

Static and dynamic polarizability for C2+ in Rydberg states

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