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

## Abstract

Here, 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. Here, we perform numerical propagation of the time-dependent Schrödinger 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.

- Authors:

- Lund Univ., Lund (Sweden); Stockholm Univ., Stockholm (Sweden)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Stockholm Univ., Stockholm (Sweden)

- Publication Date:

- Research Org.:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1410602

- Grant/Contract Number:
- AC02-76SF00515; 2014-3724; 2016-03789

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of Optics

- Additional Journal Information:
- Journal Volume: 19; Journal Issue: 11; Journal ID: ISSN 2040-8978

- Publisher:
- IOP Publishing

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; attosecond; transient absorption; ATAS; pulse characterization; continuum transition

### Citation Formats

```
Dahlström, Jan Marcus, Pabst, Stefan, and Lindroth, Eva. Attosecond transient absorption of a bound wave packet coupled to a smooth continuum. United States: N. p., 2017.
Web. doi:10.1088/2040-8986/aa8a93.
```

```
Dahlström, Jan Marcus, Pabst, Stefan, & Lindroth, Eva. Attosecond transient absorption of a bound wave packet coupled to a smooth continuum. United States. doi:10.1088/2040-8986/aa8a93.
```

```
Dahlström, Jan Marcus, Pabst, Stefan, and Lindroth, Eva. Mon .
"Attosecond transient absorption of a bound wave packet coupled to a smooth continuum". United States. doi:10.1088/2040-8986/aa8a93. https://www.osti.gov/servlets/purl/1410602.
```

```
@article{osti_1410602,
```

title = {Attosecond transient absorption of a bound wave packet coupled to a smooth continuum},

author = {Dahlström, Jan Marcus and Pabst, Stefan and Lindroth, Eva},

abstractNote = {Here, 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. Here, we perform numerical propagation of the time-dependent Schrödinger 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.},

doi = {10.1088/2040-8986/aa8a93},

journal = {Journal of Optics},

number = 11,

volume = 19,

place = {United States},

year = {2017},

month = {10}

}

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