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

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

doi:10.1063/1.479841

Cited by 27 publications

(39 citation statements)

References 61 publications

(121 reference statements)

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“…In particular, we believe that the specific rate constants of NO 2 close to the dissociation threshold -which have been the subject of a long standing debate -can now be rationalized within the concept of quantum mechanical resonances. It can indeed be calculated ab initio with good accuracy -in good agreement with experimental data [1][2][3][4][6][7][8][9][10][11]. Fig.…”

supporting

confidence: 69%

“…In high resolution double resonance experiments the full structure of resonances that partially already overlap in the threshold region is visible [7,8]. In time resolved experiments (with picosecond or femtosecond time resolution) the structure is already smoothed out by the larger bandwidths of the employed laser pulses [1,3,4,[9][10][11]. In their recent study Wittig and co-workers [2] found a good compromise between time (10 ps) and energy (3 cm À1 ) resolution.…”

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confidence: 99%

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Comment on ‘Rate coefficients for photoinitiated NO2 unimolecular decomposition: energy dependence in the threshold regime’ [Chem. Phys. Lett. 358 (2002) 71]

Abel

Grebenshchikov²,

Schinke³

et al. 2003

Chemical Physics Letters

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Recently, Wittig and co-workers have published rate coefficients kðEÞ for the unimolecular decomposition of photoinitiated NO 2 close to the dissociation threshold [Chem. Phys. Lett. 358 (2002) 71]. They found out that kðEÞ for low angular momentum J exhibits a strong increase within 25 cm À1 of the reaction threshold. The authors emphasize that their experimental results are surprising and cannot be understood quantitatively on the basis of current theory on NO 2 . In this Comment we demonstrate that recent quantum mechanical calculations of NO 2 resonances on a global 3D-potential energy surface can indeed explain their data close to the dissociation threshold as well as for larger excess energies.

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confidence: 69%

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confidence: 99%

Comment on ‘Rate coefficients for photoinitiated NO2 unimolecular decomposition: energy dependence in the threshold regime’ [Chem. Phys. Lett. 358 (2002) 71]

Abel

Grebenshchikov²,

Schinke³

et al. 2003

Chemical Physics Letters

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“…The NO 2 molecule is an exemplary system with which to study strong-field probing of photoexcited polyatomic molecules due the presence of non-adiabatic couplings between electronic states, intramolecular vibrational en- ergy redistribution (IVR) and neutral dissociation pathways. The literature associated with this system is extensive in both the frequency [24][25][26][27][28][29][30][31][32] and time domains [8][9][10][33][34][35][36][37][38][39] and hence adds to the suitability of NO 2 as an important system for studying the nature of pump-SFI probe spectroscopies in polyatomics. The photodynamics of NO 2 have been reviewed and summarised by Wilkinson and Whitaker [40].…”

Section: Introductionmentioning

confidence: 99%

Excited state wavepacket dynamics in NO2 probed by strong-field ionization

Forbes

Boguslavskiy

Wilkinson

et al. 2017

The Journal of Chemical Physics

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We present an experimental femtosecond time-resolved study of the 399 nm excited state dynamics of nitrogen dioxide using channel-resolved above threshold ionization (CRATI) as the probe process. This method relies on photoelectron-photoion coincidence and covariance to correlate the strong-field photoelectron spectrum with ionic fragments, which label the channel. In all ionization channels observed, we report apparent oscillations in the ion and photoelectron yields as a function of pump-probe delay. Further, we observe the presence of a persistent, time-invariant above threshold ionization comb in the photoelectron spectra associated with most ionization channels at long time delays. These observations are interpreted in terms of single-pump-photon excitation to the first excited electronic X̃ A state and multi-pump-photon excitations to higher-lying states. The short time delay (<100 fs) dynamics in the fragment channels show multi-photon pump signatures of higher-lying neutral state dynamics, in data sets recorded with higher pump intensities. As expected for pumping NO at 399 nm, non-adiabatic coupling was seen to rapidly re-populate the ground state following excitation to the first excited electronic state, within 200 fs. Subsequent intramolecular vibrational energy redistribution results in the spreading of the ground state vibrational wavepacket into the asymmetric stretch coordinate, allowing the wavepacket to explore nuclear geometries in the asymptotic region of the ground state potential energy surface. Signatures of the vibrationally "hot" ground state wavepacket were observed in the CRATI spectra at longer time delays. This study highlights the complex and sometimes competing phenomena that can arise in strong-field ionization probing of excited state molecular dynamics.

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“…18 Picosecond pump-and-probe photofragment spectroscopy allowed for a timeresolved investigation of the dissociation dynamics of NO 2 . [19][20][21][22][23] At energies high above the dissociation threshold, the lifetime of excited NO 2 is faster than the rotational period, such that information about excited-state dynamics could also be obtained from measurements of product angular distributions and of alignments of the rotational angular momentum with respect to the fragment recoil velocity. 24 The large number of experimental observations makes NO 2 an attractive system for examining theoretical models.…”

Section: Introductionmentioning

confidence: 99%

“…Time-resolved doubleresonance ps pump-and-probe spectroscopy was recently applied by Wittig and co-workers. 22,23 A series of rotationally resolved decomposition experiments with time-resolved detection of the forming NO was made, in which J was varied, while the quantum number K was kept close to zero. Infrared pre-excitation of NO 2 was achieved by employing a high resolution optical parametric oscillator for pre-excitation prior to ps-excitation and subsequent decomposition of the molecules.…”

Section: Introductionmentioning

confidence: 99%

Specific rate constants k(E,J) for the dissociation of NO2. I. Time-resolved study of rotational dependencies

Abel

Kirmse²,

Troe

et al. 2001

The Journal of Chemical Physics

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The effect of rotational excitation on the specific rate constants k(E,J) of the unimolecular decomposion of NO2 has been investigated. Time-resolved pump- and probe experiments with sub-ps time resolution are reported in which NO2 molecules with well-defined rotational and vibrational energy distributions were optically excited near and above the dissociation threshold. The subsequent unimolecular decay of the reacting NO2 molecules was probed by time-resolved laser-induced fluorescence of the disappearing NO2 via excitation to Rydberg states. At constant photolysis wavelength, increasing rotational energy (up to 310 cm−1) was found to leave the overall decay rate nearly unaffected. This observation can be rationalized by assuming a compensation of the angular momentum and energy dependences of the specific rate constants when J and E are changed at the same time. Keeping the total energy E nearly constant and changing J independently, the effect of rotation on the decay rate can be separated and observed more clearly. From the experimental data we conclude that, for sufficiently high J and constant total energy, molecules with larger J dissociate more slowly than molecules with small J, which is in agreement with predictions from statistical unimolecular rate theory.

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

Abstract: Specific rate constants k (E,J) for the dissociation of NO 2 . II. Linewidths of rotationally selected NO 2 near to the dissociation threshold

Cited by 27 publications

References 61 publications

Comment on ‘Rate coefficients for photoinitiated NO2 unimolecular decomposition: energy dependence in the threshold regime’ [Chem. Phys. Lett. 358 (2002) 71]

Comment on ‘Rate coefficients for photoinitiated NO2 unimolecular decomposition: energy dependence in the threshold regime’ [Chem. Phys. Lett. 358 (2002) 71]

Excited state wavepacket dynamics in NO2 probed by strong-field ionization

Specific rate constants k(E,J) for the dissociation of NO2. I. Time-resolved study of rotational dependencies

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