Nonresonant multiphoton ionization of noble gases: Theory and experiment

Perry,; Szöke, A.; Ol, Landen; Em, Campbell

doi:10.1103/physrevlett.60.1270

Cited by 118 publications

(42 citation statements)

References 10 publications

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“…These include the strong field approximation (SFA) 48 theory, the ADK formula, the ppt model and Szoke's theory. 47 One can see that the ADK formula fits only in the range where y < 0.5 in the cases of He and Ne; i.e. in the higher intensity ranges.…”

Section: Which Tunnel Ionization Formula To Use?mentioning

confidence: 96%

From Multiphoton to Tunnel Ionization

Chin

2004

Advances in Multi-Photon Processes and Spectroscopy

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Section: Which Tunnel Ionization Formula To Use?mentioning

confidence: 96%

From Multiphoton to Tunnel Ionization

Chin

2004

Advances in Multi-Photon Processes and Spectroscopy

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“…A great deal of work has concentrated on developing a theoretical framework for describing high-order processes both within and beyond the regime of perturbation theory [2,3]. Experimentalists and theoreticians alike have concentrated on atomic targets for studies of both ionization [4,5] and harmonic generation [6 -8]. Much of the observed dynamics are satisfactorily explained using a single-electron formalism in which the remaining electrons are held static [9,10].…”

Section: Introductionmentioning

confidence: 99%

High-intensity multiphoton ionization ofH2

Allendorf

Szöke

1991

Phys. Rev. A

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A tunable, high-intensity picosecond-dye-laser system has been employed with electron energy analysis to investigate the dynamics of (3+ 1) resonance-enhanced multiphoton ionization via various vibrational levels of the B 'X"and C 'Il"electronic states in H2. At the intensities studied [(0.2 -6) X 10" W/cm ], we find evidence for production of molecular ions in various vibrational levels; at the lower intensities the population distribution of final vibrational states varies with wavelength in a manner consistent with resonant enhancement at the three-photon level, followed by ionization into a vibrational level of H2+ roughly predictable by a Franck-Condon analysis of ionization out of the C state. At higher intensities, there is a shift to increased population of lower vibrational states of H2+, consistent with an ac Stark shift of the correspondingly lower vibrational levels of the C state into resonance with the three-photon energy of the laser. Clear evidence of direct dissociation of H2 followed by single-photon ionization of the excited H atom is observed as well. Above-threshold ionization of these two processes occurs readily. We also find that dissociative ionization is an increasingly important ionization pathway as the wavelength is increased. Finally, we see evidence of a fourth ionization pathway, which we tentatively assign to photoionization into a transient bound state created by the avoided crossing of the first repulsive electronic state of H2,~2po. ", n), with the single-photon-dressed ground state of Hz+, isos, n +1).

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“…A maximum focused intensity was thus calculated to be 10 17 W/cm 2 . This estimated intensity is high enough to produce fully stripped Li ions [11][12][13].Emission from a Li plasma after subpicosecond KrF laser irradiation was observed by using two spectrographs with a multichannel detector. In the wavelength range between 12 and 30 nm, a flat-field grazing-incidence XUV spectrograph with a varied-spacing concave grating (1200 lines/mm) was employed.…”

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confidence: 99%

Soft-x-ray amplification of the Lyman-α transition by optical-field-induced ionization

et al. 1993

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We report the first observation of amplification of spontaneous emission on the Lyman-a transition of hydrogenlike lithium ions by optical-field-induced ionization. Using a subpicosecond KrF laser (0.5 ps, 50 mJ) focused at 10 17 W/cm 2 , singly ionized lithium ions have been further ionized to fully stripped states, resulting in the population inversion with respect to the ground state of the hydrogenic ions. A small signal gain coefficient of 20 cm _1 was obtained.PACS numbers: 32.80. Rm, 42.55.Vc, 52.50.Jm Recent research in x-ray lasers has focused on the development of more efficient and shorter wavelength lasers which can be pumped by a compact driver. Present x-ray layers [1,2] require large scale and very expensive drivers to heat a plasma medium to a desired ionization state by collisional excitation. Recently, Burnett and co-workers [3,4], Amendt, Eder, and Wilks [5], and Eder, Amendt, and Wilks [6] have proposed a new scheme for an x-ray laser based on an optical-field-induced ionization (OFI). In this scheme, an ultrashort high-intensity laser produces a plasma consisting of fully stripped ions and cold free electrons on a time scale much shorter than the recombination time. In such a plasma, a rapid recombination cascade of the electrons could lead to a population inversion because of a sufficiently low electron temperature of the plasma. X-ray lasing by OFI, however, has not yet been demonstrated.The use of OFI for the production of an x-ray laser plasma medium introduces some favorable characteristics. First, it is possible to produce population inversions with respect to the ground state of an ion [7,8], leading to a transition to much shorter wavelength compared to relevant transitions. The transition between n=2 and 1 in H-like ions has a photon energy 5 times as large as the transition between n=3 and 2 state. Second, the use of ultrashort pulses requires a lower pump energy, compared with conventional x-ray laser schemes. The recent progress in the technology of ultrashort laser pulses would make it possible to realize table top laser drivers for OFI x-ray lasers.This Letter reports the first observation of the amplification of spontaneous emission on the Lyman-a transition (13.5 nm) in H-like Li ions, using a novel optical-fieldinduced ionization scheme. A very large small-signal gain coefficient of 20 cm ~l was obtained from the exponential growth of the 13.5 nm line intensity against the linear increase of the gain length. The anisotropy of the amplified spontaneous emission was also observed by comparing with the relative intensities along on-axis and off-axis directions.Our method described in this Letter is a unique modification of the original OFI scheme proposed previously [3][4][5][6]. In our scheme, singly ionized lithium ions which are initially prepared by a nanosecond KrF excimer laser are further ionized to a fully stripped state by a subpicosecond high-intensity KrF laser. This modified scheme provides some advantages for the production of cold electrons and for pump beam foc...

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Nonresonant multiphoton ionization of noble gases: Theory and experiment

Cited by 118 publications

References 10 publications

From Multiphoton to Tunnel Ionization

From Multiphoton to Tunnel Ionization

High-intensity multiphoton ionization ofH2

Soft-x-ray amplification of the Lyman-α transition by optical-field-induced ionization

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