Theoretical modeling of the OH stretch infrared spectrum of carboxylic acid dimers based on first-principles anharmonic couplings

Florio, Gina M.; Zwier, Timothy S.; Myshakin, Evgeniy M.; Jordan, Kenneth D.; Sibert, Edwin L.

doi:10.1063/1.1530573

Cited by 209 publications

(185 citation statements)

References 34 publications

Supporting

Mentioning

164

Contrasting

Unclassified

Order By: Relevance

“…2. The significant shift, Ϫ290 cm Ϫ1 from the OH stretch of the HONO 2 monomer, and broadening associated with the second feature are characteristic of strong hydrogen bonding, whereas the modest shift of the structured band, Ϫ52 cm Ϫ1 from free OH, suggests a weaker interaction (15). The vibrational frequencies of these features and their shifts relative to the monomers strongly suggest their assignment as the OH radical stretch ( 1 ) and the OH acid stretch ( 2 ) modes of OH-HONO 2 , particularly when compared with theoretical predictions of the spectral shifts (see below and Table 1).…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction

O’Donnell

Lester

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The reaction of nitric acid with the hydroxyl radical influences the residence time of HONO2 in the lower atmosphere. Prior studies [Brown SS, Burkholder JB, Talukdar RK, Ravishankara AR (2001) J Phys Chem A 105:1605-1614] have revealed unusual kinetic behavior for this reaction, including a negative temperature dependence, a complex pressure dependence, and an overall reaction rate strongly affected by isotopic substitution. This behavior suggested that the reaction occurs through an intermediate, theoretically predicted to be a hydrogen-bonded OH-HONO2 complex in a six-membered ring-like configuration. In this study, the intermediate is generated directly by the association of photolytically generated OH radicals with HONO2 and stabilized in a pulsed supersonic expansion. Infrared action spectroscopy is used to identify the intermediate by the OH radical stretch ( 1) and OH stretch of nitric acid ( 2) in the OH-HONO2 complex. Two vibrational features are attributed to OH-HONO2: a rotationally structured 1 band at 3516.8 cm ؊1 and an extensively broadened 2 feature at 3260 cm ؊1 , both shifted from their respective monomers. These same transitions are identified for OD-DONO 2. Assignments of the features are based on their vibrational frequencies, analysis of rotational band structure, and comparison with complementary high level ab initio calculations. In addition, the OH (v ‫؍‬ 0) product state distributions resulting from 1 and 2 excitation are used to determine the binding energy of OH-HONO2, D0 < 5.3 kcal⅐mol ؊1 , which is in good accord with ab initio predictions.atmospheric chemistry ͉ hydroxyl radical ͉ nitric acid ͉ reaction intermediate N itric acid is a chemically inactive and photochemically stable reservoir for reactive HO x and NO x species in the atmosphere. In the troposphere, HONO 2 is usually removed by dry deposition or rainout faster than it is photochemically converted back to NO x , making it a permanent sink for NO x (1, 2). In the upper troposphere and stratosphere, where there is no rain, HONO 2 can be removed by solar photolysis and reaction with OH (3, 4),This reaction results in the conversion of HONO 2 into reactive NO x species, because the unstable nitrate radical rapidly decomposes into NO or NO 2 .Kinetic studies have shown that the OH ϩ HONO 2 reaction is unusual in several respects (3, 5-11), particularly under the temperature and pressure conditions found in the lower atmosphere. Under these conditions, this reaction exhibits a negative temperature dependence, a pressure dependence, and a strong kinetic isotope effect. The indirect mechanism inferred from these studies consists of initial OH radical addition forming an energized OH-HONO 2 * intermediate, followed by redissociation or reaction to form products. The energized intermediate can also be temporarily stabilized by collisions with bath gas M, and then redissociate to reactants or decompose to products as shown in the following scheme:The unusual kinetic behavior arises because of enhanced formation and collisional st...

show abstract

Section: Resultsmentioning

confidence: 99%

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction

O’Donnell

Lester

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…[6][7][8][9][10][11][12] It is the very anharmonic nature of the hydrogen bond potentials that gives rise to the peculiar vibrational spectroscopy, [16][17][18][19][20][21][22] i.e., in essence the fact that the typical dissociation energy of a hydrogen bond is in the same range as the frequency of its vibrational modes. It has also been shown that the problem is inherently high-dimensional, [17][18][19][20][21][22] which renders the modeling of the quantum dynamics demanding and the interpretation of the computational results complicated.…”

Section: Introductionmentioning

confidence: 99%

Nonadiabatic vibrational dynamics in the HCO2−⋅H2O complex

Hamm

Stock

2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

Based on extensive ab initio calculations and the time-propagation of the nuclear Schrödinger equation, we study the vibrational relaxation dynamics and resulting spectral signatures of the OH stretch vibration of a hydrogen-bonded complex, HCO − 2 H 2 O. Despite their smallness, it has been shown experimentally by Johnson and coworkers that the gas-phase infrared spectra of these types of complexes exhibit much of the complexity commonly observed for hydrogen-bonded systems. That is, the OH stretch band exhibits a significant red shift together with an extreme broadening and a pronounced substructure, which reflects its very strong anharmonicity. Employing an adiabatic separation of time scales between the three intramolecular high-frequency modes of the water molecule and the three most important intermolecular low-frequency modes of the complex, we calculate potential energy surfaces (PESs) of the ground and the first excited states of the high-frequency modes and identify a vibrational conical intersection between the PESs of the OH stretch fundamental and the HOH bend overtone. By performing a time-dependent propagation of the resulting system, we show that the conical intersection affects a coherent population transfer between the two states, the first step of which being ultrafast (60 fs) and irreversible. The subsequent relaxation of vibrational energy into the HOH bend and ground state occurs incoherently but also quite fast (1 ps), although the corresponding PESs are well separated in energy. Owing to the smaller effective mass difference between light and heavy degrees of freedom, the adiabatic ansatz is consequently less significant for vibrations than in the electronic case. Based on the model, we consider several approximations to calculate the measured Ar-tag action spectrum of HCO − 2 H 2 O and achieve semiquantitative agreement with the experiment. Based on extensive ab initio calculations and the time-propagation of the nuclear Schrödinger equation, we study the vibrational relaxation dynamics and resulting spectral signatures of the OH stretch vibration of a hydrogen-bonded complex, HCO − 2 · H 2 O. Despite their smallness, it has been shown experimentally by Johnson and coworkers that the gas-phase infrared spectra of these types of complexes exhibit much of the complexity commonly observed for hydrogen-bonded systems. That is, the OH stretch band exhibits a significant red shift together with an extreme broadening and a pronounced substructure, which reflects its very strong anharmonicity. Employing an adiabatic separation of time scales between the three intramolecular high-frequency modes of the water molecule and the three most important intermolecular low-frequency modes of the complex, we calculate potential energy surfaces (PESs) of the ground and the first excited states of the high-frequency modes and identify a vibrational conical intersection between the PESs of the OH stretch fundamental and the HOH bend overtone. By performing a time-dependent propagation of the resulti...

show abstract

“…1 were assigned by reference to the experimental vibrational frequencies which were listed and compared to calculations by Chang et al [19] and Florio et al [20]. The characteristic changes of the vibrations caused by the dimerization are borne out in the spectra.…”

mentioning

confidence: 99%

Electron Collisions with Formic Acid Monomer and Dimer

Allan

2007

Phys. Rev. Lett.

View full text Add to dashboard Cite

Processes induced by the attachment of slow electrons to formic acid and its hydrogen-bonded dimer were studied. The elastic cross section and the cross section for the excitation of low quanta of discrete vibrations were found to be of a similar magnitude for both targets. A dramatic difference was found in the excitation of a vibrational quasicontinuum in the 1-2 eV range with the ejection of very slow electrons (E < 0:1 eV), which was about 20 more intense in the dimer. The association of two formic acid molecules to form a dimer thus dramatically increases the power to quasithermalize electrons arriving with energies in the 1-2 eV energy range. Rapid electron-driven intracluster proton transfer is invoked to explain the observation.The interest in electron-induced chemical processes has been recently renewed by the discovery that electrons at subionization [1] and even subexcitation energies [2] damage DNA. The biology-relevant discoveries inspired a series of gas phase studies of the various building blocks of DNA and other biomolecules [3,4]. The molecules in living tissue are, however, associated with neighboring molecules, often by means of hydrogen bridges, and it would thus be interesting to evaluate in what way this association affects the electron-induced processes.The dimer of formic acid is a suitable model system for such study, because it is one of the most stable neutral complexes with a complexation energy of 15 kcal mol ÿ1 (0.65 eV). The present work characterizes the collisions by means of measurement of the cross sections for vibrational excitation and for elastic scattering. The cross sections provide a detailed insight into electron-driven processes and the role played by resonances (temporary negative ions). This method was recently applied to the formic acid monomer [5]. The information obtained in this way is complementary to that obtained by studying the dissociative electron attachment, recently performed on clusters of formic acid and on condensed formic acid [6 -8], where a dramatic increase of cross sections with cluster size has been found.Particularly important for the interpretation of the present observation is the discovery, by means of anion photoelectron spectra and quantum chemical calculations, that hydrogen-bonded dimer anions of carboxylic acids (including amino acids and formic acid) and nucleic acid bases have a proton transferred from the acid to the base in their most stable structures and that this structure is reached by a barrier-free proton transfer (BFPT) [9,10]. The BFPT structure was also predicted theoretically for the formic acid dimer anion [11].Interesting phenomena were discovered in dissociative electron attachment to monomeric formic acid. The HCOO ÿ formate anion signal appeared at its energetic threshold at 1.25 eV [12]. The mechanism was clarified theoretically by Rescigno et al. [13]. High signal-to-noise ratio spectra revealed weak structures on the dissociative electron attachment band [12]. The absolute elastic cross sections as a function of sca...

show abstract

Theoretical modeling of the OH stretch infrared spectrum of carboxylic acid dimers based on first-principles anharmonic couplings

Cited by 209 publications

References 34 publications

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction

Nonadiabatic vibrational dynamics in the HCO2−⋅H2O complex

Electron Collisions with Formic Acid Monomer and Dimer

Contact Info

Product

Resources

About

Theoretical modeling of the OH stretch infrared spectrum of carboxylic acid dimers based on first-principles anharmonic couplings

Cited by 209 publications

References 34 publications

Spectroscopic identification and stability of the intermediate in the OH + HONO 2 reaction

Spectroscopic identification and stability of the intermediate in the OH + HONO 2 reaction

Nonadiabatic vibrational dynamics in the HCO2−⋅H2O complex

Electron Collisions with Formic Acid Monomer and Dimer

Contact Info

Product

Resources

About

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction

Spectroscopic identification and stability of the intermediate in the OH + HONO ₂ reaction