Femtosecond Study of Multiphoton Ionization Processes in K<sub>2</sub>:  From Pump−Probe to Control

Vivie‐Riedle, Regina de; Kobe, Kenneth A.; Manz, J.; Meyer, Wilfried; Reischl, B.; Rutz, S.; Schreiber, E.; Wöste, L.

doi:10.1021/jp952740d

Cited by 81 publications

(60 citation statements)

References 36 publications

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“…N is typically set to 40 in this work. It is time consuming to treat the ionization continuum with this model for diagonalizing the Hamiltonian matrix, but easy and accurate [15,[21][22][23].…”

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confidence: 99%

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Lou

2003

Phys. Rev. Lett.

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We report for the first time the proper conditions to observe Autler-Townes splitting (ac-Stark splitting) from vibrationally coherent states belonging to the different electronic terms of a diatomic molecule. Wave packet dynamics simulations demonstrate that such a process is feasible by multiphoton resonance ionization of the molecule Na 2 with a single ultrashort intense laser pulse. With the ultrahigh time resolution of a femtosecond laser pulse, one can directly measure the absolute value of the transition dipole moment between any kinds of molecular states by this kind of Autler-Townes splitting, which is a function of the internuclear distance R. DOI: 10.1103/PhysRevLett.91.023002 PACS numbers: 33.80.-b, 42.50.-p Atomic Autler-Townes (AT) splitting has been observed on a radio-frequency transition for a long time [1], but AT splitting in a gas-phase molecule has only recently been investigated [2 -6]. Quesada et al. [2] reported the transition dipole moment of H 2 by measuring the ratio of AT splitting to the electric field strength. Qi et al. demonstrated that the transition dipole moment of the lithium dimer could be measured by AT splitting using cw triple resonance spectroscopy [5,6]. AT splitting on the Na atom [7] and a semiconductor [8] with an ultrashort intense pulse have also been explored recently [8]. But, perhaps, because of the relatively small size of the typical molecular transition dipole moment, few papers reported any result about molecular AT splitting on vibrationally coherent states with an ultrashort laser pulse.In this Letter, with multiphoton ionization wave packet dynamics simulations, we demonstrate that one can observe AT splitting in the photoelectron spectrum with a proper single laser pulse and a prototype dimer Na 2 . Because of the direct relation of AT splitting with the local transition dipole moment and the intensity of the electric field, AT splitting can be used to precisely measure, in principle, the peak intensity of the laser pulse if the transition dipole moment is known, which is not easy to accurately determine. On the other hand, one can also measure the internuclear-distance R-dependent local transition dipole moment by AT splitting with a properly localized wave packet if the intensity of the ultrashort laser pulse is known.Along with the development of the ultrashort laser pulse, real-time molecular dynamics has been directly observed and many new phenomena have been investigated [9-13] and will be discovered. In explanation and foreseeing the experimental results, quantum wave packet dynamics simulations play the central role [14 -18]. In order to entail the excitation of a local coherent wave packet with the common available femtosecond laser system, one must choose the target molecule characterized by small vibrational energy. From this point of view, the sodium dimer is an excellent prototype molecule [12,16 -18], also for its detailed information of potential energy curves and that of its single cation [19,20]. Therefore we employed a model of the s...

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confidence: 99%

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Lou

2003

Phys. Rev. Lett.

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“…For strong pump laser fields, in the Fourier spectrum of the transient Na 2 + stimulated emission pumping signal, besides the frequencies belonging to the excited states it was also possible to observe a feature corresponding to a ground state vibration. Similar experiments were performed for K 2 and K 3 clusters (Schreiber 1995;Vivie-Riedle et al 1996;Ruppe et al 1996). A direct observation of ground state wave packet dynamics is possible by means of transient absorption in the infrared spectral region.…”

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confidence: 64%

Femtosecond time-resolved spectroscopy of elementary molecular dynamics

Kiefer

Materny

Schmitt

2002

Naturwissenschaften

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Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) is applied in order to prepare and monitor laser-induced vibrational coherences (wave packets) of different samples mainly in its electronic ground state but also in excited states. The time evolution of these wave packets gives information on the dynamics of molecular vibrations. In a first example the femtosecond (fs) CARS transients of iodine are investigated. By changing the relative delay between the applied laser pulses of this non-degenerated four-wave mixing technique, both the wavepacket motion on the electronically excited and the ground states can be detected as oscillations in the coherent anti-Stokes signal. Second we report on selective excitation of the vibrational modes in the electronic ground state of polymers of diacetylene by means of a femtosecond time-resolved CARS scheme. This selectivity is achieved by varying the phase shape (chirp) and the relative delay between the exciting laser pulses.

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“…The intramolecular relaxation processes, such as intramolecular vibrational relaxation ͑IVR͒, are the most important contributor to decoherence even in isolated molecules. Restricting IVR by optical schemes [3][4][5][6] can be an attractive route towards selective excitation in large molecular systems. Although attractive, most of the photonmediated theoretical approaches towards restricting IVR ͑also called "photon locking"͒ use complicated pulse shapes that are yet to be demonstrated in the laboratory due to stringent requirements of intensity and precision.…”

Section: Introductionmentioning

confidence: 99%

Probing coherence aspects of adiabatic quantum computation and control

Goswami

2007

The Journal of Chemical Physics

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Quantum interference between multiple excitation pathways can be used to cancel the couplings to the unwanted, nonradiative channels resulting in robustly controlling decoherence through adiabatic coherent control approaches. We propose a useful quantification of the two-level character in a multilevel system by considering the evolution of the coherent character in the quantum system as represented by the off-diagonal density matrix elements, which switches from real to imaginary as the excitation process changes from being resonant to completely adiabatic. Such counterintuitive results can be explained in terms of continuous population exchange in comparison to no population exchange under the adiabatic condition.

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Femtosecond Study of Multiphoton Ionization Processes in K₂: From Pump−Probe to Control

Cited by 81 publications

References 36 publications

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Femtosecond time-resolved spectroscopy of elementary molecular dynamics

Probing coherence aspects of adiabatic quantum computation and control

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Femtosecond Study of Multiphoton Ionization Processes in K2: From Pump−Probe to Control

Cited by 81 publications

References 36 publications

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Autler-Townes Splitting in the Multiphoton Resonance Ionization Spectrum of Molecules Produced by Ultrashort Laser Pulses

Femtosecond time-resolved spectroscopy of elementary molecular dynamics

Probing coherence aspects of adiabatic quantum computation and control

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Femtosecond Study of Multiphoton Ionization Processes in K₂: From Pump−Probe to Control