XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes
1
College of Optical Sciences, University of Arizona, Tucson, AZ 85721, USA
2
Department of Physics, University of Arizona, Tucson, AZ 85721, USA
*
Author to whom correspondence should be addressed.
Photonics 2017, 4(1), 17; https://doi.org/10.3390/photonics4010017
Received: 9 February 2017
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Accepted: 6 March 2017
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Published: 8 March 2017
(This article belongs to the Special Issue Extreme UV Lasers: Technologies and Applications)
We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is monitored in dilute helium, dense helium, and sulfur hexafluoride (SF6) molecules. We observe and quantify the time-dependence of various transient phenomena in helium atoms,includinglaser-inducedphase(LIP),time-varying(AC)Starkshift,quantumpathinterference, and laser-induced continuum structure. In the case of dense helium targets, we discuss nonlinear macroscopic propagation effects pertaining to LIP and resonant pulse propagation, which accoun tfor the appearance of new spectral features in transient lineshapes. We then use tunable NIR photons to demonstrate the wavelength dependence of the transient laser induced effects. In the case of molecular polarization experiment in SF6, we show suppression of XUV photoabsorption corresponding to inter-valence transitions in the presence of a strong NIR field. In each case, the temporal evolution of transient absorption spectra allows us to observe and understand the transient laser induced modifications of the electronic structure of atoms and molecules.
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Keywords:
XUV; attosecond; transient absorption; Fano; lineshape; strong field; atomic; molecular
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MDPI and ACS Style
Liao, C.-T.; Sandhu, A. XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes. Photonics 2017, 4, 17. https://doi.org/10.3390/photonics4010017
AMA Style
Liao C-T, Sandhu A. XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes. Photonics. 2017; 4(1):17. https://doi.org/10.3390/photonics4010017
Chicago/Turabian StyleLiao, Chen-Ting, and Arvinder Sandhu. 2017. "XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes" Photonics 4, no. 1: 17. https://doi.org/10.3390/photonics4010017
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