An experimental investigation of the effect of rotation on the rate of unimolecular decomposition of NO2

Ionov, P.I.; Bezel, Ilya; Ionov, S. I.; Wittig, C.

doi:10.1016/s0009-2614(97)88018-9

Cited by 31 publications

(33 citation statements)

References 13 publications

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“…This method enabled better absolute frequency calibration than in our preliminary report. 43,44 The uncertainty of the average pump photon energy of Ϯ10 cm Ϫ1 is due to calibration, measurement of the spectrum, and frequency drift during the scan. The pump linewidth was ϳ30 cm Ϫ1 FWHM with a smooth close-to-Gaussian shape, while the probe was ϳ50 cm Ϫ1 FWHM, which was enough to cover the main band of the NO absorption spectrum.…”

Section: Methodsmentioning

confidence: 99%

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Bezel

Ionov

Wittig

1999

The Journal of Chemical Physics

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Section: Methodsmentioning

confidence: 99%

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Bezel

Ionov

Wittig

1999

The Journal of Chemical Physics

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“…1). Previous studies using laser-induced fluorescence have characterized the picosecond dissociation in detail (14,28). However, the femtosecond conical intersection dynamics has been largely obscured by competing multiphoton processes (see (19) and references therein), requiring elaborate coincidence detection methods (29).…”

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confidence: 99%

Conical Intersection Dynamics in NO ₂ Probed by Homodyne High-Harmonic Spectroscopy

Wörner

Bertrand

Fabre

et al. 2011

Science

252

239

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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 non-adiabatic chemical reaction pathways. 1The outcome of chemical reactions is determined by the valence electronic structure of molecules. Therefore, the elucidation of elementary reaction mechanisms requires an understanding of the valence electron dynamics. Recently developed techniques that are efficient in probing valence electron dynamics include attosecond transient absorption (1), extreme ultraviolet photoelectron spectroscopy (XUV-PES) (2), high-order harmonic spectroscopy (HHS) (3-5) and strong-field ionization (6). Both time-resolved PES (7) and time-resolved HHS are sensitive to valence electron dynamics through the molecular photoionization matrix elements.Electronic dynamics in molecules are particularly challenging to observe when they are strongly coupled to nuclear dynamics. Such situations often arise in polyatomic molecules where conical intersections between the potential energy surfaces induce very rapid radiationless transitions at particular nuclear configurations (see inset of Fig. 1) (8, 9). These features channel electronic excitation into atomic motion in such diverse contexts as the primary steps of vision (10) and the dynamics underlying electron transfer and the photostability of DNA bases (11).Here we show that high-harmonic spectroscopy reveals the variations in electronic character during the conical intersection dynamics and the subsequent dissociation of nitrogen dioxide (NO 2 ). We chose NO 2 , a radical, because of its model status for theories of unimolecular dissociation (12-14) and conical intersection dynamics (15)(16)(17)(18)(19). Our results translate the previously recognized sensitivity of HHS to electronic structure into a tool for elucidating chemical reaction dynamics.High-harmonic spectroscopy can be factored into three steps: removal of an electron by an intense femtosecond laser field, acceleration of the electron in the laser field and photorecombination (20, 21). Each step contributes an amplitude and a phase to the emitted XUV radiation (20,(22)(23)(24)(25). The measurement relies on a coherent detection scheme in a transient grating geometry, using unexcited molecules as a local oscillator (4, 5). It is thus sensitive to 2 both amplitude and phase of the photorecombination matrix elements, a quantity that has recently attracted a lot of interest (26,27). Time-resolved...

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“…Previous unimolecular dissociation studies of singlet CH 2 CO 4 and NO 2 , 3 where RRKM theory has worked well, have observed a stepwise increase in the reaction rate as a function of excitation energy and have interpreted these ''steps'' as arising from the sequential passing of energetic thresholds for opening vibrational levels of the transition state. As Figs.…”

Section: B Dissociation Rates K"ejk a …mentioning

confidence: 99%

State selected unimolecular dissociation of HOCl near threshold: The 6νOH vibrational state

Dutton

Barnes

Sinha

1999

The Journal of Chemical Physics

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State-to-state unimolecular reaction dynamics of HOCl near the dissociation threshold: The role of vibrations, rotations, and IVR probed by time-and eigenstate-resolved spectroscopy J. Chem. Phys. 111, 7359 (1999); 10.1063/1.480058Direct measurement of eigenstate-resolved unimolecular dissociation rates of HOCI The spectroscopy and unimolecular dissociation dynamics of HOCl are examined by accessing rotational resonances of the 6 OH vibrational level over the K a ϭ0 -5 manifolds using overtoneovertone double resonance. The spectroscopic analysis indicates that state mixing between the zeroth-order ''bright'' O-H stretching overtone state, 6 0 0, and ''dark'' background vibrational levels is incomplete as the bright state couples to only a fraction of the available states. The coupling of 6 0 0 to a set of nearby dark states is mediated primarily by anharmonic coupling with the fourth-order vibrational resonance k 1,223 playing a particularly important role through its ability to couple the 6 0 0 state directly to the 5 2 1 vibration and indirectly to the 4 4 2 vibration. The measured state-specific unimolecular dissociation rates for 6 0 0 show large fluctuations with J and K a and are substantially slower than that expected on the basis of statistical theory. The rate fluctuations are interpreted on the basis of spectroscopic data which suggest that the fluctuations arise as a result of variation in state mixing as different dark vibrational states come in and out of resonance with the bright state for different values of J and K a .

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An experimental investigation of the effect of rotation on the rate of unimolecular decomposition of NO2

Cited by 31 publications

References 13 publications

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Conical Intersection Dynamics in NO ₂ Probed by Homodyne High-Harmonic Spectroscopy

State selected unimolecular dissociation of HOCl near threshold: The 6νOH vibrational state

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An experimental investigation of the effect of rotation on the rate of unimolecular decomposition of NO2

Cited by 31 publications

References 13 publications

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Photoinitiated unimolecular decomposition of NO2: Rotational dependence of the dissociation rate

Conical Intersection Dynamics in NO 2 Probed by Homodyne High-Harmonic Spectroscopy

State selected unimolecular dissociation of HOCl near threshold: The 6νOH vibrational state

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Conical Intersection Dynamics in NO ₂ Probed by Homodyne High-Harmonic Spectroscopy