Ice I-Lattice Dynamics and Incoherent Neutron Scattering

Prask, H. J.; Treviño, S. F.; Gault, J. D.; Logan, K. W.

doi:10.1063/1.1677682

Cited by 53 publications

(24 citation statements)

References 24 publications

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“…Quantum mechanically, sticking is expected to occur predominantly through the excitation of low frequency translational phonons, which have frequencies mostly between 50 and 60 cm −1 (between 70 and 90 K) for crystalline ice at T s = 261 K (Prask et al 1972). The frequencies should be even lower for the surface phonons.…”

Section: The Classical Trajectory Calculationsmentioning

confidence: 99%

“…For the low energy translational phonons, significant averaging is present in the classical simulations because the surface temperature used in the simulations (90 K) exceeds or is equal to the frequency of these phonons. However, there is too little averaging over the higher frequency librations of the water molecules (which peak in the range 100−300 K for crystalline ice (Prask et al 1972)). As a result, the use of the classical approximation should exaggerate the ability of the adsorbing molecule to localize in a region of coordinate space with low potential, and the calculated adsorption energy is expected to be somewhat too low; i.e.…”

Section: The Classical Trajectory Calculationsmentioning

confidence: 99%

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Adsorption of CO on amorphous water-ice surfaces

Al-Halabi

Fraser

Kroes

et al. 2004

A&A

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Abstract. We present the results of classical trajectory calculations of the adsorption of thermal CO on the surface of compact amorphous water ice, with a view to understanding the processes governing the growth and destruction of icy mantles on dust grains in the interstellar medium and interpreting solid CO infrared spectra. The calculations are performed at normal incidence, for E i = 0.01 eV (116 K) and surface temperature T s = 90 K. The calculations predict high adsorption probabilities (∼1), with the adsorbed CO molecules having potential energies ranging from −0.15 to −0.04 eV with an average energy of −0.094 eV. In all the adsorbing trajectories, CO sits on top of the surface. No case of CO diffusion inside the ice or into a surface valley with restricted access was seen. Geometry minimizations suggest that the maximum potential energy of adsorbed CO (−0.155 eV) occurs when CO interacts with a "dangling OH" group, associated with the 2152 cm −1 band seen in laboratory solid-state CO spectra. We show that relatively few "dangling OH" groups are present on the amorphous ice surface, potentially explaining the absence of this feature in astronomical spectra. CO also interacts with "bonded OH" groups, which we associate with the 2139 cm −1 infrared feature of solid CO. Our results for CO adsorption on amorphous ice are compared with those previously obtained for CO adsorption to crystalline ice. The implications of the spectroscopic assignments are discussed in terms of the solid-CO infrared spectra observed in interstellar regions. Using the Frenkel model, the lifetime τ for which CO may remain adsorbed at the surface is calculated. At temperatures relevant to the interstellar medium, i.e. 10 K, it is longer than the age of the universe, but decreases dramatically with increasing T s , such that at T s = 90 K, τ = 300 ns. The pre-exponential factor τ ν used in the Frenkel model is found to be 0.95 ± 0.02 ps. These data are compared to recent experimental results. The astrophysical implications of these calculations are discussed, with particular reference to the CO binding sites identified on amorphous ice surfaces, their adsorption energies, probabilities and lifetimes.

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Section: The Classical Trajectory Calculationsmentioning

confidence: 99%

Section: The Classical Trajectory Calculationsmentioning

confidence: 99%

Adsorption of CO on amorphous water-ice surfaces

Al-Halabi

Fraser

Kroes

et al. 2004

A&A

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“…22,23 Neutron scattering provides a wealth of information on internal and external phonons of ice, since it is not subject to selection rules and reveals the density of states beyond the k = 0 phonons. [24][25][26][27] Furthermore, the linear IR and Raman spectra of ice Ih have been investigated throughout the whole frequency range. [28][29][30][31][32][33][34] Nonlinear spectroscopic studies such as pump-probe, hole-burning, photon-echo or 2D IR spectroscopy, on the other hand, remained much more scarce.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional infrared spectroscopy of isotope-diluted ice Ih

Perakis

Widmer

Hamm

2011

The Journal of Chemical Physics

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We present experimental 2D IR spectra of isotope diluted ice Ih (i.e., the OH stretch mode of HOD in D2O and the OD stretch mode of HOD in H2O) at T = 80 K. The main spectral features are the extremely broad 1-2 excited state transition, much broader than the corresponding 0-1 groundstate transition, as well as the presence of quantum beats. We do not observe any inhomogeneous broadening that might be expected due to proton disorder in ice Ih. Complementary, we perform simulations in the framework of the Lippincott-Schroeder model, which qualitatively reproduce the experimental observations. We conclude that the origin of the observed line shape features is the coupling of the OH-vibrational coordinate with crystal phonons and explain the beatings as a coherent oscillation of the O⋅⋅⋅O hydrogen bond degree of freedom.

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“…1 The crystalline structure of ice is typically examined by using incoherent neutron scattering, which provides the density state of vibrations, and is studied theoretically by molecular dynamics simulation. 2,3 Alternatively, the non-covalent bonds between ions and water molecules could be a clue to the trapping mechanism. However, such weak bonds were difficult to observe because of the need for low frequency radiation sources and a sensitive detection technique.…”

Section: Introductionmentioning

confidence: 99%

“…11 Both results are in good agreement: a broad vibrational state density peak appears at 2 THz caused by transverse acoustic modes. 2 This prohibits the observation of other resonances overlapping with this frequency region. However, the frequency range below 2 THz, where an intense source, i.e., a photoconductive antenna, is available, would be a promising window for observing the weak interactions.…”

Section: Introductionmentioning

confidence: 99%

Detecting a Sodium Chloride Ion Pair in Ice Using Terahertz Time-domain Spectroscopy

2007

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The hydrogen bond resonance of a sodium chloride (NaCl) ion pair trapped in aqueous ice has been observed by transmission terahertz time-domain spectroscopy. The absorption peak of a sodium chloride ion pair in ice is 1.65 THz at 83 K. By investigating the interaction of the cation and anion with other chemical compounds, we deduce that the absorption peak originates from the hydrogen bond resonance of sodium chloride and water molecules. The charge redistribution that occurs when other ion pairs are added to aqueous salt solution changes the absorption spectrum. Furthermore, the results also indicate that simple molecules such as sodium halides have fingerprints in the terahertz region when the ions are trapped in ice. NaCl ion pairs in seawater and in Ringer's solution were examined.

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Ice I-Lattice Dynamics and Incoherent Neutron Scattering

Cited by 53 publications

References 24 publications

Adsorption of CO on amorphous water-ice surfaces

Adsorption of CO on amorphous water-ice surfaces

Two-dimensional infrared spectroscopy of isotope-diluted ice Ih

Detecting a Sodium Chloride Ion Pair in Ice Using Terahertz Time-domain Spectroscopy

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