Generalized multiphoton-ionization cross sections of the rare gases for 500-fs, 248.6-nm pulses

Uiterwaal, Cornelis; Xenakis, D.; Charalambidis, D.; Maragakis, Paul; Schröder, H.; Lambropoulos, P.

doi:10.1103/physreva.57.392

“…In the case of unconfined medium interacting with a focused Gaussian beam, the saturation regime is described by the 3/2 power law [49]. In the present experiment, the interaction region is confined to the jet size and, therefore, the polynomial exponent is smaller than 3/2 due to the partial elimination of interaction volume effects [50]. One should note that the saturation intensity is defined by the laser pulse duration and the ionization rate, which is dependent on the order of nonlinearity of the ionization process.…”

Section: Intensity Studiesmentioning

confidence: 56%

Ultrafast photoelectron spectroscopy of solutions: space-charge effect

Al-Obaidi

¹

,

Wilke

²

,

Borgwardt

³

et al. 2015

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The method of time-resolved XUV photoelectron spectroscopy is applied in a pump-probe experiment on a liquid micro-jet. We investigate how the XUV energy spectra of photoelectrons are influenced by the space charge created due to ionization of the liquid medium by the pump laser pulse. XUV light from high-order harmonic generation is used to probe the electron population of the valence shell of iron hexacyanide in water. By exposing the sample to a short UV pump pulse of 266 nm wavelength and ∼55 fs duration, we observe an energy shift of the spectral component associated with XUV ionization from the Fe 3d(t 2g ) orbital as well as a shift of the water spectrum. Depending on the sequence of the pump and probe pulses, the arising energy shift of photoelectrons acquires a positive or negative value. It exhibits a sharp positive peak at small time delays, which facilitates to determine the temporal overlap between pump and probe pulses. The negative spectral shift is due to positive charge accumulated in the liquid medium during ionization. Its dissipation is found to occur on a (sub)nanosecond time scale and has a biexponential character. A simple meanfield model is provided to interpret the observations. A comparison between the intensity dependencies of the spectral shift and the UV ionization yield shows that the space-charge effect can be significantly reduced when the pump intensity is attenuated below the saturation level of water ionization. For the given experimental conditions, the saturation intensity lies at 6 10 10 W cm −2 .

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“…Only in recent years has it become possible to treat with quantitative rigour the response of helium (or any two-electron atomic system) to intense light [10][11][12][13][14][15][16][17][18]. In this paper, we presented calculations of helium single-ionization rates, (I ), from the UV to the static-field limit.…”

Section: Discussionmentioning

confidence: 99%

From the UV to the static-field limit: rates and scaling laws of intense-field ionization of helium

Parker¹,

Armstrong²,

Boca³

et al. 2009

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

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We present high-accuracy calculations of ionization rates of helium at UV (195 nm) wavelengths. The data are obtained from full-dimensionality integrations of the helium-laser time-dependent Schrödinger equation. Comparison is made with our previously obtained data at 390 nm and 780 nm. We show that scaling laws introduced by Parker et al extend unmodified from the near-infrared limit into the UV limit. Static-field ionization rates of helium are also obtained, again from time-dependent full-dimensionality integrations of the helium Schrödinger equation. We compare the static-field ionization results with those of Scrinzi et al and Themelis et al, who also treat the full-dimensional helium atom, but with time-independent methods. Good agreement is obtained.

show abstract

“…Only in recent years has it become possible to treat with quantitative rigour the response of helium (or any two-electron atomic system) to intense light [10][11][12][13][14][15][16][17][18]. In this paper, we presented calculations of helium single-ionization rates, (I ), from the UV to the static-field limit.…”

Section: Discussionmentioning

confidence: 99%

From the UV to the static-field limit: Rates and scaling laws for intense-field ionization of helium

Armstrong¹,

Parker²,

Boca³

et al. 2009

J. Phys.: Conf. Ser.

0

View full text Add to dashboard Cite

We present high-accuracy calculations of ionization rates of helium at UV (195 nm) wavelengths. The data are obtained from full-dimensionality integrations of the helium-laser time-dependent Schrödinger equation. Comparison is made with our previously obtained data at 390 nm and 780 nm. We show that scaling laws introduced by Parker et al extend unmodified from the near-infrared limit into the UV limit. Static-field ionization rates of helium are also obtained, again from time-dependent full-dimensionality integrations of the helium Schrödinger equation. We compare the static-field ionization results with those of Scrinzi et al and Themelis et al, who also treat the full-dimensional helium atom, but with time-independent methods. Good agreement is obtained.

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Generalized multiphoton-ionization cross sections of the rare gases for 500-fs, 248.6-nm pulses

Cited by 28 publications

References 17 publications

Ultrafast photoelectron spectroscopy of solutions: space-charge effect

Ultrafast photoelectron spectroscopy of solutions: space-charge effect

From the UV to the static-field limit: rates and scaling laws of intense-field ionization of helium

From the UV to the static-field limit: Rates and scaling laws for intense-field ionization of helium

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