Femtosecond to nanosecond relaxation time scales in electronically excited tetrakis(dimethylamino)ethylene: identification of the intermediates

Soep, B.; Mestdagh, J. M.; Sorgues, S.; Visticot, J. P.

doi:10.1007/s100530170217

Cited by 20 publications

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“…This fixes the time scale for argon atom losses from the TDMAE + (Ar) n cluster ions. Before discussing the experimental results of the previous section, we must recall some of the results obtained in our laboratory on the dynamics of the TDMAE molecule either when free [4,5] or coated by many argon atoms [6].…”

Section: Methodsmentioning

confidence: 99%

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Femtosecond photodissociation dynamics of van der Waals cationic clusters: a tool for detecting metastable isomers of organic cations

Sorgues

Mestdagh

Soep

et al. 2004

Chemical Physics Letters

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To cite this version:S. Sorgues, J. M. Mestdagh, B. Soep, J. P. Visticot. Femtosecond Photodissociation Dynamics of van der Waals Cationic Clusters: a tool for detecting metastable isomers of organic cations. Chemical Physics Letters, Elsevier, 2004, 391, pp.254-258 A femtosecond pump (266 nm)-probe (800 nm) experiment as been performed on small clusters of tetrakis(dimethylamino)ethylene (TDMAE) with argon (TDMAE(Ar) ≪10 ). The pump excites TDMAE and initiates deformations of the molecule within the cluster. Then, the probe ionises TDMAE and disposes enough excess energy in the cluster to evaporate all argon atoms. However, ionisation during the first 150 fs after the pump gives preferentially access to a metastable configuration of the TDMAE + ion, unquenched by the argon environment. This takes up enough of the excess energy to prevent complete argon evaporation. Observing the non-total-evaporation of weakly bond clusters formed of an organic cation with argon appears as a useful tool to reveal the existence of such metastable configurations in organic cations.

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Section: Methodsmentioning

confidence: 99%

“…Because of the CI, the change of the electronic configuration, which can be viewed as a non-radiative V to Z energy transfer, occurs with no surface hopping of the wavepacket. The time constant for the V to Z energy transfer is 300 fs [4]. Of course, the wavepacket launched on the excited surface is accelerated on the slopes of this surface.…”

Section: Methodsmentioning

confidence: 99%

Femtosecond photodissociation dynamics of van der Waals cationic clusters: a tool for detecting metastable isomers of organic cations

Sorgues

Mestdagh

Soep

et al. 2004

Chemical Physics Letters

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“…The femtosecond dynamics of free excited TDMAE has been studied in details in our group [19][20][21]. The dynamics that takes place during the first few picoseconds following the excitation by the pump laser at 266 nm, has been interpreted within the simple framework of an interplay between electronic configurations of the central CC bond, as that would be the case in regular alkenes.…”

Section: A Reminder Of the Free Tdmae Dynamicsmentioning

confidence: 99%

“…It mostly concerns gas phase, femtosecond pump-probe investigations in organic molecules documenting ultrafast energy relaxation processes [15][16][17][18][19][20][21], isomerisation reactions [22][23][24][25] and ring opening reactions [26][27][28][29][30][31]. Ethylene [18,32], substituted ethylene compounds [18][19][20][21] and polyenes [22] received a particular attention. One of the most surprising observations is that such wavepacket movements may create observable molecular oscillations when passing either through [33] or near a CI [20].…”

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Dynamics of excited tetrakis(dimethylamino)ethylene solvated by argon atoms

et al. 2004

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The supersonic expansion of a mixture of the title molecule (TDMAE) with argon generates a beam carrying a log-normal distribution of TDAME(Ar) n clusters, broadly centered atn ≈ 60. The femtosecond pump-probe technique is used to investigate the excited state dynamics of these clusters up to a 220 ps delay between the pump and the probe. This documents the effect of the argon environment on the TDMAE dynamics. The TDMAE molecule is excited in the valence state V within the cluster by the pump laser at 266 nm. It undergoes deformation in the excited potential energy surface that brings the initial wavepacket to a conical intersection (CI) where the electronic configuration of the molecule switches to a Zwitterionic configuration Z. Compared to the behaviour of free TDMAE, the effect of the argon environment is a slow down of the wavepacket movement and an increase of the time scale of the V-Z energy transfer from 300 fs to 400 ± 50 fs. This slow down effect, that we call a chistera effect, differs from a standard cage effect. Here, the deforming molecule does not experience a hard sphere collision with the argon cage, rather it pushes it away. Furthermore, umbrella oscillations of the dimethylamino groups are excited when the initial wavepacket passes the CI region. Because of the argon environment, the sharp 250 fs oscillation period of the free molecules is transformed into a broad structure of 40 fs width (FWHM) centred at about 240 fs. In addition, breathing oscillations of the argon environment with respect to the TDMAE molecule are observed with a period of 410 ± 40 fs. Finally, long delays between the pump and the probe lasers allow us to investigate the non radiative energy transfer from the Z electronic configuration of TDMAE(Ar) n to a charge transfer state. The effect of the evaporation of argon atoms in the neutral and the ionised clusters has been taken into account, as its time scale accompanies that of the observed phenomena.

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Micro solvation dynamics at the passage of conical intersections observed in argon clusters of excited tetrakis(dimethylamino) ethylene

Sorgues¹,

Mestdagh²,

Gloaguen³

et al. 2004

Femtochemistry and Femtobiology

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Femtosecond to nanosecond relaxation time scales in electronically excited tetrakis(dimethylamino)ethylene: identification of the intermediates

Cited by 20 publications

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Femtosecond photodissociation dynamics of van der Waals cationic clusters: a tool for detecting metastable isomers of organic cations

Femtosecond photodissociation dynamics of van der Waals cationic clusters: a tool for detecting metastable isomers of organic cations

Dynamics of excited tetrakis(dimethylamino)ethylene solvated by argon atoms

Micro solvation dynamics at the passage of conical intersections observed in argon clusters of excited tetrakis(dimethylamino) ethylene

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