On the low-frequency vibrational spectrum of water |
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Authors: | Rosario Sergio Cataliotti |
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Institution: | 1. Dipartimento di Scienze Chimiche , Università di Catania , Viale A.Doria, 6, I-95125, Catania, Italy rcatalio@unict.it |
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Abstract: | A new assignment is proposed for the low-frequency region of the vibrational spectrum of water, based on a comparison of the times of relevant occurring events. The time-matching is made between the dynamics of the rupture and formation time of the hydrogen bond, and the so-called bending and stretching oscillation periods of the O–H ··· O tetrahedral network. The same assignment also emerges by comparing thermal and solute concentration effects. Furthermore, a critical re-examination of the literature already existing on the subject corroborates the now proposed assignments for the modes at 60 and 170 cm?1. These are considered to arise first from a transverse acoustic phonon with a low-frequency contribution sensitive to temperature and concentration effects, and second from external motions such as translations or restricted rotations of small water clusters inside a cage, and subjected to its potential field. |
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Keywords: | Raman frequencies low frequencies liquids local density approximations vibrational spectroscopy |
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