An ab initio and dynamics study of the photodissociation of nitric acid HNO3

Nonella, Marco; Suter, H. U.; Huber, J. Robert

doi:10.1016/j.cplett.2010.01.005

Cited by 6 publications

(6 citation statements)

References 26 publications

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“…7 The energy differences between these two electronically excited states and the ground state are 3.40 and 4.54 eV, respectively. 7,62 Once a HNO 3 molecule absorbs a 308 nm photon, it can be excited into the first electronically excited 1 1 A″ state due to the fact that the absorption band is broad and the vertical excitation energy is 3.73 eV. In terms of electronic structure, the transition essentially involves excitation of an electron from a nonbonding NO 2 molecular orbital to a NO 2 π* antibonding orbital in HNO 3 , with symmetry a′→a″ (C s ).…”

Section: The Journal Of Physical Chemistry Amentioning

confidence: 99%

Photolysis of Nitric Acid at 308 nm in the Absence and in the Presence of Water Vapor

et al. 2015

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We have re-examined the NOx channels from the 308 nm gas-phase photolysis of nitric acid (HNO3) by using excimer laser photolysis combined with cavity ring-down spectroscopy. The photolysis products were monitored in the 552-560 and 640-648 nm regions. Direct comparison of the photolysis product spectrum in the 640-648 nm region with literature vibronic band origins and line intensities in electronically excited NO2 (NO2*) suggests that NO2* is not formed from HNO3 photolysis at 308 nm. A comparison of the photolysis product spectrum in the 552-560 nm region with a standard NO2 spectrum indicates that ground-state NO2 is a photolysis product. We have determined the NO2 quantum yield from the 308 nm HNO3 photolysis. We also investigated HNO3 photolysis in the presence of water vapor. For equilibrated HNO3/H2O mixtures, we did not observe significant variation of product absorption around 552 nm with delay times between the firing of the photolysis and the probe lasers. Transient product absorption measurements at 342.0 and 343.5 nm (respective wavelengths where the peak and valley of HONO absorptions are located) are consistent with ground-state NO2 being the predominant NOx product from the 308 nm photolysis of a HNO3/H2O mixture. Atmospheric implications are also discussed.

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Section: The Journal Of Physical Chemistry Amentioning

confidence: 99%

Photolysis of Nitric Acid at 308 nm in the Absence and in the Presence of Water Vapor

et al. 2015

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“…More recently, Avila and Carrington [59,60] have performed full-dimensional variational calculations with a particular focus on how to make such studies efficient. None of these studies considered transition intensities and amongst various ab initio studies using more approximate treatments [61][62][63][64][65][66], only Lee and Rice [61] appear to have considered (harmonic) intensities.…”

Section: Introductionmentioning

confidence: 99%

A hybrid variational-perturbation calculation of the ro-vibrational spectrum of nitric acid

Pavlyuchko

Yurchenko

Tennyson

2015

The Journal of Chemical Physics

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Rotation-vibration spectra of the nitric acid molecule, HNO3, are calculated for wavenumbers up to 7000 cm(-1). Calculations are performed using a Hamiltonian expressed in internal curvilinear vibrational coordinates employing a hybrid variational-perturbation method. An initial potential energy surface (PES) and dipole moment function (DMF) are calculated ab initio at the CCSD(T)/aug-cc-pVQZ level of theory. Parameters of the PES and DMF are varied to minimize differences between the calculated and experimental transition frequencies and intensities. The average, absolute deviation between calculated and experimental values is 0.2 cm(-1) for frequencies in the fundamental bands and 0.4 cm(-1) for those in the first overtone and lowest combination bands. For the intensities, the calculated and experimental values differ by 0.3% and 40% for the fundamentals and overtones, respectively. The optimized PES and DMF are used to calculate the room-temperature ro-vibrational spectrum. These calculation reproduce both the form of the absorption bands and fine details of the observed spectra, including the rotational structure of the vibrational bands and the numerous hot absorption band. Many of these hot bands are found to be missing from the compilation in HITRAN. A room temperature line list comprising 2 × 10(9) lines is computed.

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“…The energetics obtained in this study by full geometry optimization at the CASPT2 level differs considerably from that observed on the 2D-PES at the CASSCF level. 21 There is a local minimum S 3 -1 which is slightly deviated from planar. Consequently, there is a small barrier S 3 -1-TS1 for the N-O4 dissociation.…”

Section: Channels At High Excitation Energymentioning

confidence: 98%

“…8,14 Recently, Huber et al provided a possible explanation for the reason why the O( 1 D) + HONO channel became predominant. 21 They prepared a two-dimensional PES (2D-PES) for NQO2 and N-O4 distances at a CASSCF level for the S 3 state, and performed wave packet dynamical simulations. Their 2D-PES/CASSCF was completely repulsive along both NQO2 and N-O4 dissociation coordinates.…”

Section: Channels At High Excitation Energymentioning

confidence: 99%

“…Head-Gordon and coworkers 20 computed vertical excitation energies of singlet and triplet excited states using the CIS, CIS(D), and CCSD methods. Huber et al 21 carried out wave packet dynamics simulations on two-dimensional potential functions and discussed two dissociation pathways (O + HONO and OH + NO 2 ) on the S 3 surface and one dissociation pathway (OH + NO 2 ) on the S 1 surface. Vaida et al 22 and Lester et al 23 studied infrared overtone spectroscopy by a joint experimental and theoretical work.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical insight into the wavelength-dependent photodissociation mechanism of nitric acid

Xiao

Maeda

Morokuma

2016

Phys. Chem. Chem. Phys.

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Photodissociation pathways of HNO3 involving the four lowest electronic singlet states (S0, S1, S2 and S3) were studied by the MS-CAS(12e,8o)PT2/6-31+G* method. All critical points, i.e. minima, transition states and minimum energy conical intersections, were explored systematically by the global reaction route mapping (GRRM) strategy utilizing the anharmonic downward distortion following (ADDF) method. Some key structures were also optimized at the MS-CAS(16e,12o)PT2/aug-cc-pVDZ level. Based on structures and relative energies of these critical points, we discussed the wavelength-dependent photodissociation mechanism of HNO3 in detail. The OH(X(2)Π) dissociation was found to occur through four pathways on the S1, S2, and S3 surfaces depending on the excitation energy, and one of the four pathways was shown to undergo the excited state roaming mechanism. The experimental appearance energy of the O((1)D) dissociation channel at 538.8 kJ mol(-1) was attributed to a conical intersection between the S2 and S3 surfaces. It has been shown experimentally that the O((1)D) channel was dominant at the higher excitation energy. In this study, its mechanistic reason was explained by the shape of the S3 surface and locations of important critical points.

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An ab initio and dynamics study of the photodissociation of nitric acid HNO3

Cited by 6 publications

References 26 publications

Photolysis of Nitric Acid at 308 nm in the Absence and in the Presence of Water Vapor

Photolysis of Nitric Acid at 308 nm in the Absence and in the Presence of Water Vapor

A hybrid variational-perturbation calculation of the ro-vibrational spectrum of nitric acid

Theoretical insight into the wavelength-dependent photodissociation mechanism of nitric acid

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