Infrared spectrum of HDO in aqueous solutions of perchlorates and tetrafluoroborates

Brink, George; Falk, Michael

doi:10.1139/v70-509

Cited by 56 publications

(24 citation statements)

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“…At high mole ratios where there is still a much greater number of H,O molecules than excess acid protons, there is an overall shifting of intensity towards higher frequency as N decreases; intensity decreases in the 3250 cm-' region and increases in the 3400-3600 cm-' region. These effects are very similar to those observed for C104-salt solutions (26)(27)(28)(29)(30)(31)(32)(33)(34)(35), and the shift of intensity is usually taken to imply that hydrogen bonding of the water surrounding the C104-ion is weakened (the so-called structure-breaking effect).…”

Section: ( a ) Effects Of Perchlorate Ionsupporting

confidence: 60%

Vibrational spectral studies of solutions at elevated temperatures and pressures. VI. Raman studies of perchloric acid

Ratcliffe¹,

Irish²

1984

Can. J. Chem.

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. J. Chem. 62, 1134Chem. 62, (1984.Raman spectra of perchloric acid in water have been measured for solutions spanning a wide concentration range and, for two specific concentrations, a wide range of temperatures. The acid is completely dissociated down to a water:acid mole ratio of about 1.8 at room temperature. At elevated temperatures it is still a very "strong" acid. As the concentration increases the apparent symmetry of the C10,-ion decreases and a small amount of a new species assigned as associated C10,-(H,,)' can be detected. The effects on the OH stretching bands of water, of temperature, C10,-, and the excess acid protons are discussed.C. I. RATCLIFFE et D. E. IRISH. Can. J. Chem. 62, 1134 (1984.On a mesurC les spectres Raman de l'acide perchlorique en solution aqueuse pour un large intervalle de concentrations et Cgalement, pour deux concentrations spkcifiques, pour un large intervalle de tempkratures. A la tempCrature ambiante, I'acide est completement dissociC jusqu'i un rapport molaire eau : acid d'environ 1,8. A des temperatures plus ClevCes, I'acide demeure un acide trks "fort". Lorsque la concentration augmente, la symttrie apparente de I'ion CIO,-diminue et on peut dtceler la presence d'une faible quantitC d'une nouvelle espkce identifite comme Ctant I'ion associC C 1 0 , -(H,,)'. On discute des effets de la tempirature, du C10,-et des protons acides en excks sur les bandes d'klongation OH de I'eau.[Traduit par le journal] Introduction As the temperature of water rises K, increases (1, 2) and hydrolysis reactions are encountered more frequently in salt-water mixtures (3, 4). Such reactions can be controlled or prevented, of course, by controlling the acidity. At ambient temperatures perchloric acid is often used to control pH because the perchlorate ion does not complex with most cations and the acid is strong. (A recent determination suggests that there is no association above a water:acid mole ratio, N = nH20/n,,,d, of 1.8 ( 3 . ) Thus competing equilibria can frequently be neglected. When studying the properties of salts in water at elevated temperatures, it is important to know if these useful properties of perchloric acid are retained. Also, for the measurement of relative integrated Raman band intensities, an internal intensity standard is generally employed and at moderate temperatures the v , line of the perchlorate ion is most frequently the preference for the reasons cited above. Thus, for our longer term goals, knowledge of the temperature dependence of the Raman spectra of aqueous solutions of perchloric acid is essential. It was also of interest to see if the much reduced dielectric constant of water at higher temperatures might promote formation of HC104. (Nitric and sulfuric acids show markedly enhanced association as the temperature increases.)Swaddle et al. (6) have studied the kinetics of decomposition of 1.1-6.6 m aqueous perchloric acid in the range 295-332°C. (At 250°C very little, if any, decomposition occurs at these concentrations.) The reaction is autocatalytic and t...

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Section: ( a ) Effects Of Perchlorate Ionsupporting

confidence: 60%

Vibrational spectral studies of solutions at elevated temperatures and pressures. VI. Raman studies of perchloric acid

Ratcliffe¹,

Irish²

1984

Can. J. Chem.

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“…The blue shift in maximum absorption has been assigned to a signature of broken hydrogen bonds. 31,32 However, there is no splitting in the hydroxyl stretch region, as it is observed in perchlorate or pseudohalide ion solutions, 7,16 where it is thought that solvation and bulk waters have such distinct vibrational frequencies that the ODstretch band is separated into two peaks. In the case of N − 3 , no such distinction between bulk and solvation waters can be made by linear absorption spectroscopy.…”

Section: A Linear Spectramentioning

confidence: 98%

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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“…Its peak position is independent of concentration. This peak is attributed to ODs bonded to the BF 4 Ϫ anions (16). In addition, the water peak shifts to the blue with increasing concentration but essentially maintains its shape.…”

Section: Resultsmentioning

confidence: 93%

“…For this anion, the stretch spectrum of hydroxyls bound to BF 4 Ϫ is substantially shifted to the blue, and the band is relatively narrow (16). The hydroxylanion peak is readily observable on the high-frequency side of the broad hydroxyl-oxygen band (see Fig.…”

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confidence: 93%

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Ion–water hydrogen-bond switching observed with 2D IR vibrational echo chemical exchange spectroscopy

Moilanen

Wong

Rosenfeld

et al. 2009

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

233

318

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The exchange of water hydroxyl hydrogen bonds between anions and water oxygens is observed directly with ultrafast 2D IR vibrational echo chemical exchange spectroscopy (CES). The OD hydroxyl stretch of dilute HOD in H 2O in concentrated (5.5 M) aqueous solutions of sodium tetrafluoroborate (NaBF 4) displays a spectrum with a broad water-like band (hydroxyl bound to water oxygen) and a resolved, blue shifted band (hydroxyl bound to BF 4 ؊ ).At short time (200 fs), the 2D IR vibrational echo spectrum has 4 peaks, 2 on the diagonal and 2 off-diagonal. The 2 diagonal peaks are the 0 -1 transitions of the water-like band and the hydroxylanion band. Vibrational echo emissions at the 1-2 transition frequencies give rise to 2 off-diagonal peaks. On a picosecond time scale, additional off-diagonal peaks grow in. These new peaks arise from chemical exchange between water hydroxyls bound to anions and hydroxyls bound to water oxygens. The growth of the chemical exchange peaks yields the time dependence of anionwater hydroxyl hydrogen bond switching under thermal equilibrium conditions as T aw ‫؍‬ 7 ؎ 1 ps. Pump-probe measurements of the orientational relaxation rates and vibrational lifetimes are used in the CES data analysis. The pump-probe measurements are shown to have the correct functional form for a system undergoing exchange.2D IR spectroscopy ͉ hydration of ions ͉ hydrogen bond dynamics ͉ ion hydrogen bonds chemical exchange ͉ ionic solutions W ater interacting with ions occurs in a wide variety of systems ranging from ocean salt water to water interacting with charged amino acids at the surfaces of proteins (1). The properties of pure liquid water are determined by the nature of its hydrogen bond network. A water molecule can have as many as 4 hydrogen bonds with other water molecules, forming an approximately tetrahedral structure. The pure water hydrogen bond network is constantly evolving with a range of time scales from tens of femtoseconds to picoseconds (2-5). Hydrogen bonds are continually forming and breaking through concerted hydrogen bond rearrangements (6). These dynamical processes can be observed on the time scale they occur in considerable detail by using ultrafast infrared spectroscopy. Measurements of spectral diffusion, described in terms of the frequencyfrequency correlation function (FFCF), by using ultrafast 2D IR vibrational echo spectroscopy (3,7,8) as well as other ultrafast IR techniques (4, 5) have determined the multiple time scales for the hydrogen bond dynamics. The slowest time component of the FFCF (1.7 ps) is associated with the randomization of the hydrogen bond network through concerted hydrogen bond rearrangements. The orientational relaxation time of pure water (2.6 ps) (2, 5) is also assigned to concerted hydrogen bond rearrangement via jump reorientation (6).In aqueous salt solutions the structure of water is modified in the vicinity of the ions as the water oxygens preferentially solvate the cations and the water hydroxyls solvate the anions (9, 10). The structures of the hyd...

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Infrared spectrum of HDO in aqueous solutions of perchlorates and tetrafluoroborates

Cited by 56 publications

References 11 publications

Vibrational spectral studies of solutions at elevated temperatures and pressures. VI. Raman studies of perchloric acid

Vibrational spectral studies of solutions at elevated temperatures and pressures. VI. Raman studies of perchloric acid

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

Ion–water hydrogen-bond switching observed with 2D IR vibrational echo chemical exchange spectroscopy

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