Intensity of the second and third OH overtones of H2O2, HNO3, and HO2NO2

Zhang, Hui; Roehl, Coleen M.; Sander, Stanley P.; Wennberg, P. O.

doi:10.1029/2000jd900118

Cited by 37 publications

(71 citation statements)

References 15 publications

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“…Thus, the NIDL provides for a good alternative to both of these methods. Figure 12 shows the NIDL plots drawn using experimental data points for four lower-overtone transitions in the OH stretches of nitric acid and methanol (Brown et al, 2000;Donaldson et al, 1998;Feierabend et al, 2004Feierabend et al, , 2006Lange et al, 2001;Phillips et al, 1998;Zhang et al, 2000) collected by Lane and Kjaergaard (2010), Table XII. Obviously, the NIDL is obeyed rather accurately and hence can be used to make predictions for the higher transitions.…”

Section: Application Of the Nidl For Prediction Of The Higher Overmentioning

confidence: 99%

Towards understanding the nature of the intensities of overtone vibrational transitions

Medvedev

2012

The Journal of Chemical Physics

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The overtone vibrational transitions, i.e., transitions between states separated by more than one vibrational quantum play important role in many fields of physics and chemistry. The overtone transition is a purely quantum process associated with the so-called dynamical tunneling [Heller, E. J., "The many faces of tunneling," J. Phys. Chem. A 103(49), 10433-10444 (1999)] whose probability is small as compared to the fundamental transition. The transition probability is proportional to the Landau-Lifshitz tunneling factor similar to the Gamov factor in nuclear physics. However, as opposed to the Gamov tunneling, the Landau-Lifshitz tunneling lacks any barrier to tunnel through: Its probability looks as if the system were forced to "dive" under the barrier up to a point where the transition can be performed without any change in momentum, hence with a high probability, and then to "emerge back" in a new state. It follows that the transition probability is associated with the shape of the potential in the classically forbidden region in the same sense as the transition energy is associated with the shape of the potential in the classically allowed region, as implied by the Bohr-Sommerfeld quantization rule, and in the same sense as the probability of the Gamov tunneling is associated with the shape of the potential within the barrier region. As soon as the tunneling character of the transition is recognized, the well-known extreme sensitivity of the overtone intensities to small variations of the fitting function representing the molecular potential [Lehmann, K. K. and Smith, A. M., "Where does overtone intensity come from?" J. Chem. Phys. 93(9), 6140-6147 (1990)] becomes fully understood: Small variations of the potential in the classical region, which do not affect the energy levels significantly, cause large variations in the forbidden region and hence do affect the tunneling factor. This dictates a clear strategy of constructing the potential energy and dipole moment functions (PEF and DMF) capable of explaining the data of vibrational spectroscopy and possessing a predictive power. In this paper, we will show that, for stretching vibrations, knowledge of the inner wall of the PEF is necessary to perform this task. Incorrect behavior of the PEF at extremely small interatomic separations corresponding to energies well above the dissociation limit results in an incorrect rate of the intensity falloff, hence a rapid increase of discrepancies between the calculated and observed intensities with overtone number. Analysis of experimental data on some di- and polyatomic molecules and their interpretations is presented, which shows that neglecting the tunneling nature of overtone transitions does not permit making predictions of the intensities with a known uncertainty. A new approach has to be developed. First of all, an ab initio PEF giving correct energy levels and having correct behavior of the repulsive wall must be constructed; thereafter, an ab initio DMF is invoked to explain the experimental data for lower (obs...

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Section: Application Of the Nidl For Prediction Of The Higher Overmentioning

confidence: 99%

Towards understanding the nature of the intensities of overtone vibrational transitions

Medvedev

2012

The Journal of Chemical Physics

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“…Since HNO 3 is well reproduced in the upper troposphere an additional conversion of HNO 3 to NO x , as suggested by Jacob et al [1996] for this region to explain the discrepancy found in the NO x /HNO 3 ratio, would therefore be at odds with the simulation of HNO 3 . An additional channel for HNO 4 photolysis at long wavelengths (>760 nm) has been reported [e.g., Zhang et al, 2000;Roehl et al, 2002]. In the model $60 pmol/mol of HNO 4 are calculated at 10 km, insufficient to fully explain the underestimate in NO of $150 pmol/mol.…”

Section: Airborne Measurementsmentioning

confidence: 99%

A model for studies of tropospheric ozone and nonmethane hydrocarbons: Model evaluation of ozone‐related species

et al. 2003

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[1] A global three-dimensional model for studies of the tropospheric chemistry of HO x , ozone, and their precursors is thoroughly evaluated with available observations of 15 species from surface stations and/or aircraft campaigns. The effect of grid-resolution was studied by comparing the measurements to model runs at a high ($1.9°Â 1.9°) and a reduced resolution. This study is a follow-up to a previous paper where the model was described and results for ozone were discussed. A statistical analysis of the complete comparison of each species is also presented in order to serve as a quantitative baseline for future evaluations. The seasonality and magnitude of the CO abundance is well simulated except for an overestimate of up to 20 nmol/mol in southern low latitudes. The tropospheric mean methane lifetime is calculated to be 8.7 and 9.1 years for the high-and low-resolution run, respectively, in agreement with recent estimates. Industrial emissions of alkanes from North America appear to be too low in the current data set. Indications for a biogenic source of propane were found by comparing with measurements over the Amazon rain forest. Alkene emissions from oceans are underestimated in the model indicating that they are higher than previous studies suggested. Nitrogen species are mostly reproduced within a factor of 2 or better, but a general bias to underestimate HNO 3 and to overpredict peroxyacetyl nitrate (PAN), especially in remote regions could also be found. NO was well simulated in the lower and mid troposphere, but significantly understimated in the upper troposphere. A sensitivity run shows that studies are needed to better constrain the rate constants for the thermal equilibrium of PAN. Acetone is often underestimated indicating that additional wide-spread sources, likely oceanic, are present. The comparison with other oxygenated species (acetaldehyde, methanol, formic and acetic acid) indicates severe gaps in our understanding of the present budgets of these species. In particular the underestimate of acetaldehyde implies large missing sources (order 100 Tg/yr) of this compound.

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“…Current recommendations [ DeMore et al , 1997; Sander et al , 2000] indicate very large uncertainties in these parameters (factors of 2 and 5 in the unimolecular decomposition rate coefficients). In addition, spectroscopic studies to carefully quantify photolytic processes in the ultraviolet, visible and near‐infrared spectral regions are also needed to verify those that have been performed [ Zhang et al , 2000]; more recent studies do indicate that near infrared photolysis of HO 2 NO 2 is indeed important [ Roehl et al , 2002]. These uncertainties lead directly to uncertainties in calculated concentrations of these species.…”

Section: Budgets Of Peroxy Radicalsmentioning

confidence: 99%

Steady state free radical budgets and ozone photochemistry during TOPSE

et al. 2003

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[1] A steady state model, constrained by a number of measured quantities, was used to derive peroxy radical levels for the conditions of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign. The analysis is made using data collected aboard the NCAR/NSF C-130 aircraft from February through May 2000 at latitudes from 40°to 85°N, and at altitudes from the surface to 7.6 km. HO 2 + RO 2 radical concentrations were measured during the experiment, which are compared with model results over the domain of the study showing good agreement on the average. Average measurement/model ratios are 1.04 (s = 0.73) and 0.96 (s = 0.52) for the MLB and HLB, respectively. Budgets of total peroxy radical levels as well as of individual free radical members were constructed, which reveal interesting differences compared to studies at lower latitudes. The midlatitude part of the study region is a significant net source of ozone, while the high latitudes constitute a small net sink leading to the hypothesis that transport from the middle latitudes can explain the observed increase in ozone in the high latitudes. Radical reservoir species concentrations are modeled and compared with the observations. For most conditions, the model does a good job of reproducing the formaldehyde observations, but the peroxide observations are significantly less than steady state for this study. Photostationary state (PSS) derived total peroxy radical levels and NO/NO 2 ratios are compared with the measurements and the model; PSS-derived results are higher than observations or the steady state model at low NO concentrations.

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Intensity of the second and third OH overtones of H₂O₂, HNO₃, and HO₂NO₂

Cited by 37 publications

References 15 publications

Towards understanding the nature of the intensities of overtone vibrational transitions

Towards understanding the nature of the intensities of overtone vibrational transitions

A model for studies of tropospheric ozone and nonmethane hydrocarbons: Model evaluation of ozone‐related species

Steady state free radical budgets and ozone photochemistry during TOPSE

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