Attosecond transient absorption of a bound wave packet coupled to a smooth continuum

Dahlström, Jan MarcusStockholm University,Lunds universitet,Stockholms universitet,Fysikum,Lund University, Sweden,Atomfysik,Fysiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Atomic Physics,Department of Physics,Departments at LTH,Faculty of Engineering, LTH (author)

We investigate the possibility of using transient absorption of a coherent bound electron wave packet in hydrogen as an attosecond pulse characterization technique. In a recent work, we have shown that photoionization of such a coherent bound electron wave packet opens up for pulse characterization with unprecedented temporal accuracy-independent of the atomic structure-with maximal photoemission at all kinetic energies given a wave packet with zero relative phase (Pabst and Dahlstrom Phys. Rev. A 94 13411 (2016)). Here, we perform numerical propagation of the time-dependent Schrodinger equation and analytical calculations based on perturbation theory to show that the energy-resolved maximal absorption of photons from the attosecond pulse does not uniquely occur at a zero relative phase of the initial wave packet. Instead, maximal absorption occurs at different relative wave packet phases, distributed as a non-monotonous function with a smooth -pi/2 shift across the central photon energy (given a Fourier-limited Gaussian pulse). Similar results are also found in helium. Our finding is surprising, because it implies that the energy-resolved photoelectrons are not mapped one-to-one with the energy-resolved absorbed photons of the attosecond pulse.

NATURVETENSKAP Fysik hsv//swe
NATURAL SCIENCES Physical Sciences hsv//eng
NATURVETENSKAP Fysik Atom- och molekylfysik och optik hsv//swe
NATURAL SCIENCES Physical Sciences Atom and Molecular Physics and Optics hsv//eng
attosecond
transient absorption
ATAS
pulse characterization
continuum transition
ATAS
attosecond
continuum transition
pulse characterization
transient absorption

Pabst, StefanStanford Linear Accelerator Center (SLAC),Harvard–Smithsonian Center for Astrophysics (author)
Lindroth, EvaStockholm University,Stockholms universitet,Fysikum(Swepub:su)lindr (author)
Stockholms universitetFysikum (creator_code:org_t)

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NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Atom and Molecul ...

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