Simon:Wave packet theory of dynamic absorption spectra in femtosecond pump–probe experiments

J. Chem. Phys. 92, 4012 (1990); http://dx.doi.org/10.1063/1.457815 (18 pages)

Wave packet theory of dynamic absorption spectra in femtosecond pump–probe experiments

W. Thomas Pollard, Soo‐Y. Lee, and Richard A. Mathies

Department of Chemistry, University of California, Berkeley, California 94720 

(Received 18 July 1989; accepted 8 December 1989)

•   Alerts 
•   Tools 
•   Share  

• Abstract
• References (64)
• Citing Articles (136)

The large spectral width of ultrashort optical pulses makes it possible to measure the complete time‐resolved absorption spectrum of a sample with a single pulse, offering simultaneously high resolution in both the time and frequency domains. To quantitatively interpret these experiments, we start with the usual perturbative density matrix theory for the third‐order susceptibility of a multilevel system. However, the theory is formulated in terms of four‐time correlation functions which are interpreted as the time‐dependent overlap of bra and ket vibrational wave packets propagating independently on the ground and excited electronic state potential surfaces. This approach captures the critical distinction between electronic population decay and pure dephasing processes, while retaining the intuitive physical picture offered by the time‐dependent wave packet theories of molecular spectroscopy. A useful simplification is achieved by considering the absorption of the probe pulse as the first‐order spectroscopy of the nonstationary state created by the pump pulse. In this case, the dynamic spectrum is obtained through the Fourier transform of the time‐dependent overlap of the initial wave packet propagating on its potential surface and a second wave packet, created by the probe pulse, which evolves simultaneously on the final surface. Calculations for model systems using harmonic surfaces and δ‐function pulses are presented to illustrate the application of this theory and to clarify the unique spectral behavior of the nonstationary states created in femtosecond pump–probe experiments. Finally, we demonstrate the practical application of the theory for anharmonic surfaces and finite pulses by analyzing the dynamic spectroscopy of the excited state torsional isomerization of the bacteriorhodopsin chromophore.

Sebastien: Attosecond Control of Orbital Parity Mix Interferences and the Relative Phase of Even and Odd Harmonics in an Attosecond Pulse Train

Phys. Rev. Lett. 109, 083001 (2012) [5 pages]

Attosecond Control of Orbital Parity Mix Interferences and the Relative Phase of Even and Odd Harmonics in an Attosecond Pulse Train

Abstract

References

No Citing Articles

Download: PDF (5,330 kB) Export: BibTeX or EndNote (RIS)

G. Laurent^*, W. Cao, H. Li, Z. Wang, I. Ben-Itzhak, and C. L. Cocke
Physics Department, James R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas 66506, USA

Received 19 March 2012; published 20 August 2012

We experimentally demonstrate that atomic orbital parity mix interferences can be temporally controlled on an attosecond time scale. Electron wave packets are formed by ionizing argon gas with a comb of odd and even high-order harmonics, in the presence of a weak infrared field. Consequently, a mix of energy-degenerate even and odd parity states is fed in the continuum by one- and two-photon transitions. These interfere, leading to an asymmetric electron emission along the polarization vector. The direction of the emission can be controlled by varying the time delay between the comb and infrared field pulses. We show that such asymmetric emission provides information on the relative phase of consecutive odd and even order harmonics in the attosecond pulse train.

© 2012 American Physical Society

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.109.083001

DOI:

10.1103/PhysRevLett.109.083001

PACS:

32.80.Rm, 32.80.Qk, 42.65.Ky

Thomas: Theoretical study of photoelectron angular distributions in single-photon ionization of aligned N2 and CO2

Phys. Rev. A 81, 033421 (2010)  http://pra.aps.org/abstract/PRA/v81/i3/e033421

Theoretical study of photoelectron angular distributions in single-photon ionization of aligned N2 and CO2

the angular distribution of the momenta of XUV ionised electrons is going to bare much relevance to the XUV initiated HHG experiment which is being constucted in the basement at the moment. i would like to take this journal club as an opportunity to involve both theoreticians and experimentalists in a discussion about the differing properties of XUV and tunnel ionised electrons and how we can use these properties to our advantage. i would also like to discuss the possibilities of writing a ral proposal for attempting to measure the ion state resolved angular distribution of the emitted electrons. for experimentalists all that theory has been prompted by J. Phys. Chem. A2008, 112, 9382–9386.

Malte: Strong field quantum control in CO2 in (1+2+3) steps

The polarisation dependence of double ionisation in CO2 and dissociative excitation of the parent ion
has been investigated experimentally via laser induced impulsive alignment. For the ?first time, the
recollision contribution to these channels is identifi?ed unambiguously and resolved angularly. This
is achieved by employing an elliptically polarised probe pulse, which maintains a main polarisation
direction while switching of? recollision. It was found that tunnel-ionisation from lower lying orbitals
in the neutral and thus higher lying excited states in the parent ion are involved in all of the investigated
processes, even at relatively low intensities. While CO+ is formed almost exclusively via tunnel ionisation from HOMO-2 followed by strong ?field excitation, recollision was found to be a signi?cant channel for O+ production. A strong polarisation dependence in both channels enables varying the associated branching ratios and demonstrates the possibility of strong fi?eld quantum control via the laser polarisation.

Zara: Coupling between energy and phase in hollow-core fiber based f-to-2f interferometers

Journal club about the paper:


"Coupling between energy and phase in hollow-core fiber based f-to-2f interferometers "
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-14-12082


also read:
"Determining the phase-energy coupling coefficient in carrier-envelope phase measurements"
http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-32-7-796

Bridgette: Laser Enabled Auger Decay in Atoms and Molecules: Probing Electron Correlation in Inner-valence ionised States

Auger type decay processes play a fundamental role in atomic/molecular spectroscopy, sur-
face analysis, radiation damage, etc. These transitions can be viewed as consisting of two steps.
Firstly, a high energy photon produces a hole in an inner electronic shell, emitting a photoelec-
tron with kinetic energy dependent on the incident photon. Then the hole is lled by a valence
electron and a second valence electron is emitted with energy dependent on the energy levels of
the singly and doubly charged ions and not the incident photon energy. Auger decay processes
are considered to be an important manifestation of electron correlation as they are only possible
because of electron-electron interactions.

Recently, Murnane and Kapteyn [1] have investigated Laser-Enabled Auger Decay (LEAD)
in the multi-photon regime for vacancies that are not energetic enough to undergo the normal
Auger decay. Here we show that if considered in the single-photon regime, the LEAD process
provides a valuable insight into electron correlation in the inner valence ionised states. Firstly,
we analyse the single photon LEAD for the 2s-ionised state in Ne . A detailed investigation of
the mechanism of this single-photon LEAD process reveals that it is only possible because the
initial 2s-1 one-hole state contains con gurations of the type two holes and an electron excited
to a high-energy orbital. The cross-section of the single-photon LEAD process becomes a direct
measure of this con guration mixing. We use the rst-principles algebraic diagrammatic con-
struction (ADC) scheme and the Stieltjes imaging technique[2] to evaluate the single-photon
LEAD cross-sections in ns-ionised states of Ne and Ar. The correlation in the inner valence
ionised states of trans-1,3 Butadiene are investigated as they are an example of a molecule with
strong con guration mixing resulting in the breakdown of the molecular orbital (MO) picture
of ionisation[3]. We show that the breakdown of the MO picture leads to a dramatic increase
of the single-photon LEAD cross-section relative to the atomic case. Finally, we propose that
single photon LEAD can be a sensitive experimental probe for the attosecond hole migration
triggered by the MO breakdown.


1 P. Ranitovic, X. M. Tong, C. W. Hogle, X. Zhou, Y. Liu, N. Toshima, M. M. Murnane,
H. C. Kapteyn, Phys. Rev. Lett. 106, 053002 (2011).
2 See e.g. K. Gokhberg, V. Vysotskiy, L. S. Cederbaum, L. Storchi, F. Tarantelli, V. Averbukh,
J. Chem. Phys. 130, 064104 (2009).
3 L. S. Cederbaum, W. Domcke, J. Schirmer, W. Von Niessen, Adv. Chem. Phys. 65, 115
(1986).

Amelle: Conical Intersection Dynamics in NO2 Probed by Homodyne High-Harmonic Spectroscopy

Conical Intersection Dynamics in NO₂ Probed by Homodyne High-Harmonic Spectroscopy

1. H. J. Wörner¹,²,*, 
2. J. B. Bertrand¹, 
3. B. Fabre³, 
4. J. Higuet³, 
5. H. Ruf³, 
6. A. Dubrouil³, 
7. S. Patchkovskii¹, 
8. M. Spanner¹,
9. Y. Mairesse³, 
10. V. Blanchet⁴, 
11. E. Mével³, 
12. E. Constant³, 
13. P. B. Corkum¹, 
14. D. M. Villeneuve¹

+Author Affiliations

1. ¹Joint Laboratory for Attosecond Science, National Research Council of Canada and University of Ottawa, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6.
2. ²Laboratorium für Physikalische Chemie, Eidgenössische Technische Hochschule Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland.
3. ³Centre Lasers Intenses et Applications, Université de Bordeaux, CEA, CNRS, UMR5107, 351 Cours de la Libération, 33405 Talence, France.
4. ⁴Laboratoire Collisions Agrégats Réactivité (IRSAMC), UPS, Université de Toulouse, F-31062 Toulouse, France and CNRS, UMR 5589, F-31062 Toulouse, France

1. ↵*To whom correspondence should be addressed. E-mail: woerner@phys.chem.ethz.ch

ABSTRACT

Conical intersections play a crucial role in the chemistry of most polyatomic molecules, ranging from the simplest bimolecular reactions to the photostability of DNA. The real-time study of the associated electronic dynamics poses a major challenge to the latest techniques of ultrafast measurement. We show that high-harmonic spectroscopy reveals oscillations in the electronic character that occur in nitrogen dioxide when a photoexcited wave packet crosses a conical intersection. At longer delays, we observe the onset of statistical dissociation dynamics. The present results demonstrate that high-harmonic spectroscopy could become a powerful tool to highlight electronic dynamics occurring along nonadiabatic chemical reaction pathways.

http://www.sciencemag.org/content/334/6053/208