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Two-color pump-probe experiments in helium using high-order harmonics

Johansson, Allan LU ; Raarup, MK ; Li, Zhongshan LU ; Lokhnygin, V ; Descamps, D ; Lynga, C ; Mevel, E ; Larsson, Jörgen LU orcid ; Wahlström, Claes-Göran LU and Aloise, S , et al. (2003) In European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics 22(1). p.3-11
Abstract
A pump-probe technique has been applied for measuring the lifetimes and absolute photoionization cross-sections of excited He states. The 1s2p P-1 and 1s3p P-1 states of He are excited by using the 13th and the 14th harmonic, respectively, of a tunable 70 ps dye laser generated in a Kr gas jet. The states are ionized after a varying time delay, by absorption of probe photons with energies between 1.6 and 4.5 eV. Lifetimes of tau(1s2p) = 0.57 ns and tau(1s3p) = 1.76 ns are determined with a precision of about 15%. A significant enhancement of the number of ions present in the lifetime curves at zero time delay for pressures above 6 x 10(-5) mbar is attributed to direct two-photon ionization of He in combination with AC Stark broadening of... (More)
A pump-probe technique has been applied for measuring the lifetimes and absolute photoionization cross-sections of excited He states. The 1s2p P-1 and 1s3p P-1 states of He are excited by using the 13th and the 14th harmonic, respectively, of a tunable 70 ps dye laser generated in a Kr gas jet. The states are ionized after a varying time delay, by absorption of probe photons with energies between 1.6 and 4.5 eV. Lifetimes of tau(1s2p) = 0.57 ns and tau(1s3p) = 1.76 ns are determined with a precision of about 15%. A significant enhancement of the number of ions present in the lifetime curves at zero time delay for pressures above 6 x 10(-5) mbar is attributed to direct two-photon ionization of He in combination with AC Stark broadening of the excited state and absorption of the XUV light in the medium. Absolute photoionization cross-sections from the He 1s2p P-1 and He 1s3p P-1 states in the threshold region are determined by measuring the saturation of the ionization process with a precision of similar to 25%. In addition, the variation of the relative orientation between the polarization vectors of the pump and probe beams enables the determination of partial photoionization cross-sections. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics
volume
22
issue
1
pages
3 - 11
publisher
EDP Sciences
external identifiers
  • wos:000180850000001
  • scopus:0037263791
ISSN
1434-6060
DOI
10.1140/epjd/e2002-00213-1
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Atomic physics (011013005), Physics, Faculty of Technology (011013200)
id
be754200-c4d8-4a46-82c8-bf5aa403f02d (old id 318685)
date added to LUP
2016-04-01 15:27:57
date last changed
2022-01-28 05:27:11
@article{be754200-c4d8-4a46-82c8-bf5aa403f02d,
  abstract     = {{A pump-probe technique has been applied for measuring the lifetimes and absolute photoionization cross-sections of excited He states. The 1s2p P-1 and 1s3p P-1 states of He are excited by using the 13th and the 14th harmonic, respectively, of a tunable 70 ps dye laser generated in a Kr gas jet. The states are ionized after a varying time delay, by absorption of probe photons with energies between 1.6 and 4.5 eV. Lifetimes of tau(1s2p) = 0.57 ns and tau(1s3p) = 1.76 ns are determined with a precision of about 15%. A significant enhancement of the number of ions present in the lifetime curves at zero time delay for pressures above 6 x 10(-5) mbar is attributed to direct two-photon ionization of He in combination with AC Stark broadening of the excited state and absorption of the XUV light in the medium. Absolute photoionization cross-sections from the He 1s2p P-1 and He 1s3p P-1 states in the threshold region are determined by measuring the saturation of the ionization process with a precision of similar to 25%. In addition, the variation of the relative orientation between the polarization vectors of the pump and probe beams enables the determination of partial photoionization cross-sections.}},
  author       = {{Johansson, Allan and Raarup, MK and Li, Zhongshan and Lokhnygin, V and Descamps, D and Lynga, C and Mevel, E and Larsson, Jörgen and Wahlström, Claes-Göran and Aloise, S and Gisselbrecht, M and Meyer, M and L'Huillier, Anne}},
  issn         = {{1434-6060}},
  language     = {{eng}},
  number       = {{1}},
  pages        = {{3--11}},
  publisher    = {{EDP Sciences}},
  series       = {{European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics}},
  title        = {{Two-color pump-probe experiments in helium using high-order harmonics}},
  url          = {{https://lup.lub.lu.se/search/files/4398572/2374968.pdf}},
  doi          = {{10.1140/epjd/e2002-00213-1}},
  volume       = {{22}},
  year         = {{2003}},
}