Hydration Dynamics of Aqueous Nitrate

Thøgersen, Jan; Réhault, Julien; Odelius, Michael; Ogden, T.; Jena, Naresh K.; Jensen, Svend J. Knak; Keiding, Søren Rud; Helbing, Jan

doi:10.1021/jp310090u

Cited by 79 publications

(87 citation statements)

References 52 publications

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“…This suggests that nitrate anions experience a greater chemical heterogeneity in their solvation environment at the surface of ice compared to the bulk. 43,50 Indeed, NO3 -adsorption on aqueous interfaces was studied previously using electronic structure methods and their asym-NOstr. splittings were shown to be strongly correlated with their intramolecular distortion 49,60 and to be of the same magnitude as those reported herein.…”

Section: Resultsmentioning

confidence: 99%

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Surface-Enhanced Nitrate Photolysis on Ice

et al. 2015

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Abstract:Heterogeneous nitrates photolysis is the trigger for many chemical processes occurring in the polar boundary layer and is widely believed to occur in a quasiliquid layer (QLL) at the surface of ice. The dipole forbidden character of the electronic transition relevant to boundary layer atmospheric chemistry and the small photolysis/photoproducts quantum yields in ice (and in water) may confer a significant enhancement and interfacial specificity to this important photochemical reaction at the surface of ice. Using amorphous solid water films at cryogenic temperatures as models for the disordered interstitial air/ice interface within the snowpack suppresses the diffusive uptake kinetics thereby prolonging the residence time of nitrate anions at the surface of ice. This approach allows their slow heterogeneous photolysis kinetics to be studied providing the first direct evidence that nitrates adsorbed onto the first molecular layer at the surface of ice are photolyzed more effectively than those dissolved within the bulk. Vibrational spectroscopy allows the ~3-fold enhancement in photolysis rates to be correlated with the nitrates' distorted intramolecular geometry thereby hinting at the role played by the greater chemical heterogeneity in their solvation environment at the surface of ice than in the bulk. A simple 1D kinetic model suggests 1-that a 3(6)-fold enhancement in photolysis rate for nitrates adsorbed onto the ice surface could increase the photochemical NO2 emissions from a 5(8) nm thick photochemically active interfacial layer by 30%(60)%, and 2-that 25%(40%) of the NO2 photochemical emissions to the snowpack interstitial air are released from the top-most molecularly thin surface layer on ice. These findings may provide a new paradigm for heterogeneous (photo)chemistry at temperatures below those required for a QLL to form at the ice surface.

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Section: Resultsmentioning

confidence: 99%

“…In addition, vibrational spectroscopy also enabled the intramolecular NO3 -geometrical distortions and symmetry to be probed, 43 through its effects on the asymmetric NO stretching vibrations (hereafter, asym-NOstr.) of surface nitrates or bulk nitrates, providing important information on their local solvation environment.…”

Section: Methodsmentioning

confidence: 99%

Surface-Enhanced Nitrate Photolysis on Ice

et al. 2015

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“…Full- and near-degeneracy of quantum state structure is a common scenario especially in the vibrational modes of highly symmetric molecules. 24,34–39 In the present work we report the direct observation of the coherence dynamics of tricyanomethanide anion (TCM) in water. TCM has become the focus of extensive research due to its possible application in ionic liquids.…”

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confidence: 99%

Quantum Beats and Coherence Decay in Degenerate States Split by Solvation

Chuntonov

Kuroda

Ghosh

et al. 2013

J. Phys. Chem. Lett.

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Coherent dynamics of degenerate quantum states symmetry-broken on the femtosecond timescale is found to exhibit the phenomenon of quantum beats. Frequency-resolved and polarization-selective heterodyned transient grating spectroscopy enabled us to retrieve the oscillation pattern characteristic of the beating in systems undergoing ultrafast dynamical processes. This methodology applies to the general phenomena of coherence dynamics which is important in any ultrafast multidimensional spectroscopy. A particular application to the vibrational spectroscopy of coherence in the degenerate normal modes of the tricyanomethanide anion solvated in water is explored in this study. The relaxation of the cross-polarization transient grating anisotropy is shown to reflect the loss of the vibrational coherence, which is caused by ultrafast dynamics of the water solvation shell.

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“…This advantage added to the sub-picosecond time resolution makes non-linear ultrafast spectroscopies the preferred tool to elucidate the dynamics and mechanism of processes occurring in water. [20][21][22][23][24][25] In this work, ultrafast IR pump-probe, two dimensional infrared (2D IR), and linear absorption IR spectroscopies are used to characterize the vibrational dynamics of the carboxylate asymmetric stretch of betaine. Furthermore, to obtain the atomistic model giving rise to the observed vibrational dynamics of betaine, the conformational and hydration dynamics of betaine are studied using ab initio molecular dynamics.…”

Section: Introductionmentioning

confidence: 99%

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

Cui

Mathaga

et al. 2015

The Journal of Chemical Physics

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Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm −1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ∼0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters. C 2015 AIP Publishing LLC. [http://dx

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Hydration Dynamics of Aqueous Nitrate

Cited by 79 publications

References 52 publications

Surface-Enhanced Nitrate Photolysis on Ice

Surface-Enhanced Nitrate Photolysis on Ice

Quantum Beats and Coherence Decay in Degenerate States Split by Solvation

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

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