Large Angular Jump Mechanism Observed for Hydrogen Bond Exchange in Aqueous Perchlorate Solution

Ji, Minhe; Odelius, Michael; Gaffney, Kelly J.

doi:10.1126/science.1187707

Cited by 192 publications

(227 citation statements)

References 24 publications

(63 reference statements)

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“…Recently, the jump mechanism has also been experimentally validated for ionic solutions via polarisation-selective two-dimensional infrared (2D-IR) spectroscopy. 7 This contrasts with the "dynamical iceberg" theory, as presented by Rezus and Bakker. 8 There, with the aid of infrared pump-probe spectroscopy, the authors observe a significant (almost an order of magnitude) slow down of solvation shell water reorientation times in highly concentrated solutions, as compared to bulk water.…”

Section: Introductionmentioning

confidence: 59%

Azide–water intermolecular coupling measured by two-color two-dimensional infrared spectroscopy

Borek

Perakis

Kläsi

et al. 2012

The Journal of Chemical Physics

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We utilize two-color two-dimensional infrared spectroscopy to measure the intermolecular coupling between azide ions and their surrounding water molecules in order to gain information about the nature of hydrogen bonding of water to ions. Our findings indicate that the main spectral contribution to the intermolecular cross-peak comes from population transfer between the asymmetric stretch vibration of azide and the OD-stretch vibration of D2O. The azide-bound D2O bleach/stimulated emission signal, which is spectrally much narrower than its linear absorption spectrum, shows that the experiment is selective to solvation shell water molecules for population times up to 500 fs. The waters around the ion are present in an electrostatically better defined environment. Afterwards, 1 ps, the sample thermalizes and selectivity is lost. On the other hand, the excited state absorption signal of the azide-bound D2O is much broader. The asymmetry in spectral width between bleach/stimulated emission versus excited absorption has been observed in very much the same way for isotope-diluted ice Ih, where it has been attributed to the anharmonicity of the OD potential. Azide-water intermolecular coupling measured by two-color two-dimensional infrared spectroscopy We utilize two-color two-dimensional infrared spectroscopy to measure the intermolecular coupling between azide ions and their surrounding water molecules in order to gain information about the nature of hydrogen bonding of water to ions. Our findings indicate that the main spectral contribution to the intermolecular cross-peak comes from population transfer between the asymmetric stretch vibration of azide and the OD-stretch vibration of D 2 O. The azide-bound D 2 O bleach/stimulated emission signal, which is spectrally much narrower than its linear absorption spectrum, shows that the experiment is selective to solvation shell water molecules for population times up to ∼500 fs. The waters around the ion are present in an electrostatically better defined environment. Afterwards, ∼1 ps, the sample thermalizes and selectivity is lost. On the other hand, the excited state absorption signal of the azide-bound D 2 O is much broader. The asymmetry in spectral width between bleach/stimulated emission versus excited absorption has been observed in very much the same way for isotope-diluted ice Ih, where it has been attributed to the anharmonicity of the OD potential.

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Section: Introductionmentioning

confidence: 59%

Azide–water intermolecular coupling measured by two-color two-dimensional infrared spectroscopy

Borek

Perakis

Kläsi

et al. 2012

The Journal of Chemical Physics

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“…The correlation times apparent from the 2D spectra and the mixed quantum-classical derived frequency calculations are well below the picosecond HB lifetimes reported here and in the literature, 14,22 i.e., we are able to discern sub-100 fs structural fluctuations from slower hydrogen bond exchange dynamics. Owing to the short vibrational lifetimes of 300 fs, these exchange processes do not contribute significantly to the observed 2D line shapes.…”

Section: Discussionmentioning

confidence: 67%

“…Two-dimensional infrared (2D IR) spectroscopy with a femtosecond time resolution allows for mapping molecular dynamics and extracting couplings strengths. Recent 2D IR experiments and theoretical modeling of OH or OD stretch vibrations in neat bulk water, [6][7][8][9][10] at water surfaces, 11,12 in ionic solutions [13][14][15] as well as in hydration shells of DNA and phospholipids [16][17][18][19][20][21] have provided detailed insight into the underlying time scales. In the bulk, thermally excited librational motions of H 2 O molecules modulate existing HB geometries on a 50 fs time scale.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast phosphate hydration dynamics in bulk H2O

Costard

Tyborski

Fingerhut

et al. 2015

The Journal of Chemical Physics

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Phosphate vibrations serve as local probes of hydrogen bonding and structural fluctuations of hydration shells around ions. Interactions of H2PO4− ions and their aqueous environment are studied combining femtosecond 2D infrared spectroscopy, ab-initio calculations, and hybrid quantum-classical molecular dynamics (MD) simulations. Two-dimensional infrared spectra of the symmetric (νS(PO2−)) and asymmetric (νAS(PO2−)) PO2− stretching vibrations display nearly homogeneous lineshapes and pronounced anharmonic couplings between the two modes and with the δ(P-(OH)2) bending modes. The frequency-time correlation function derived from the 2D spectra consists of a predominant 50 fs decay and a weak constant component accounting for a residual inhomogeneous broadening. MD simulations show that the fluctuating electric field of the aqueous environment induces strong fluctuations of the νS(PO2−) and νAS(PO2−) transition frequencies with larger frequency excursions for νAS(PO2−). The calculated frequency-time correlation function is in good agreement with the experiment. The ν(PO2−) frequencies are mainly determined by polarization contributions induced by electrostatic phosphate-water interactions. H2PO4−/H2O cluster calculations reveal substantial frequency shifts and mode mixing with increasing hydration. Predicted phosphate-water hydrogen bond (HB) lifetimes have values on the order of 10 ps, substantially longer than water-water HB lifetimes. The ultrafast phosphate-water interactions observed here are in marked contrast to hydration dynamics of phospholipids where a quasi-static inhomogeneous broadening of phosphate vibrations suggests minor structural fluctuations of interfacial water.

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“…Polarization sensitive two-dimensional infrared (2D-IR) spectroscopy in combination with Car-Parrinello MD modeling suggest that the water molecules that are hydrogen bonded to the ion reorient in sudden large angle jumps involving the concerted breading of a hydrogen bond to the ion and the formation of a hydrogen bond to a water molecules in the second hydration shell. 11 In between the angular jumps the water molecules slowly reorient with the ion in an intact ion-water shell.…”

Section: Introductionmentioning

confidence: 99%

“…10 On the other hand, experimental evidence that a jump mechanism is responsible for the reorientation of water in the solvation shell of ions has been presented recently. 11,12 The hydrogen bond network changes considerably when ions are dissolved in water.…”

Section: Introductionmentioning

confidence: 99%

Hydration Dynamics of Aqueous Nitrate

et al. 2013

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Aqueous nitrate, NO3-(aq), was studied by 2D-IR, UV-IR, and UV-UV time-resolved spectroscopies in combination with molecular dynamics (MD) simulations with the purpose of determining the hydration dynamics around the anion. In water, the D3h symmetry of NO3-is broken, and the degeneracy of the asymmetric-stretch modes is lifted. This provides a very sensitive probe of the ionwater interactions. The 2D-IR measurements reveal excitation exchange between the two nondegenerate asymmetric-stretch vibrations on a 300-fs time scale concomitant with fast anisotropy decay of the diagonal-peak signals. The MD simulations show that this is caused by jumps of the transition dipole orientations related to fluctuations of the hydrogen bonds connecting the nitrate ion to the nearest water molecules. Reorientation of the ion, which is associated with the hydrogen-bond breaking, was monitored by time-resolved UV-IR and UV-UV spectroscopy, revealing a 2-ps time constant. These time scales are very similar to those reported for isotope-labeled water, suggesting that NO3-(aq) has a labile hydration shell. connecting the nitrate ion to the nearest water molecules. Reorientation of the ion, which is associated with the hydrogen bond breaking, is monitored by time resolved UV-IR-and UV-UV spectroscopy, revealing a 2 ps time constant. These time scales are very similar to those reported for isotope-labeled water, suggesting that NO 3¯( aq) has a labile hydration shell.

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Large Angular Jump Mechanism Observed for Hydrogen Bond Exchange in Aqueous Perchlorate Solution

Cited by 192 publications

References 24 publications

Azide–water intermolecular coupling measured by two-color two-dimensional infrared spectroscopy

Azide–water intermolecular coupling measured by two-color two-dimensional infrared spectroscopy

Ultrafast phosphate hydration dynamics in bulk H2O

Hydration Dynamics of Aqueous Nitrate

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