Molecular energy transfer in liquid water
SPEAKER: Rossend Rey (SIMCON, DFEN, UPC).
TITLE: Molecular energy transfer in liquid water
DATE / PLACE: 11am 29/11/2012, sala de reunions B5-211
ABSTRACT:
Liquid water is the matrix of crucial processes that involve the molecular excitation of the surrounding water molecules, or even the direct formation of water molecules in excited states. Understanding the mechanisms by which excess molecular energy is channelled back to equilibrium is thus of fundamental interest. We show here, for the case of neat water, how this can be done via a detailed analysis of energy fluxes between molecular modes [1,2,3,4].
Such analysis is carried out through the computation of the various contributions to the power and the work on the initially excited mode. In this way one can determine, for instance, which percentage of vibrational energy flows into self-rotation through centrifugal coupling, and to which particular axis this flow is maximal [1,2]. Moreover the spatial extent of energy flow into other water molecules can be ascertained as well, together with the specific molecular modes (translational, rotational) to which excess energy is transferred [3,4]. To this end, classical nonequilibrium MD runs are conducted for neat liquid water, so that at the initial time either: (a) the bend mode of a single flexible water molecule is excited or, (b) a purely rotational excitation is created for a single rigid molecule.
Bend relaxation is found to be dominated by energy flow to the hindered rotation of the bend excited water molecule, due to a 2:1 Fermi resonance for the centrifugal coupling between the water bend and rotation. The remaining energy flow from the excited water bend is dominated by transfer to rotations of the first hydration shell. The later statement is also valid for the flow ensuing direct rotational excitation of the central water molecule.
The basic conclusion is that about ninety per cent of the initial excess energy is channeled through rotational energy of immediate neighbours, for both vibrational and rotational excitations.
[1] F. Ingrosso, R. Rey, T. Elsaesser, J.T. Hynes, J. Phys. Chem A 113, 6657 (2009).
[2] R. Rey, F. Ingrosso, T. Elsaesser, J.T. Hynes, J. Phys. Chem A 113, 8949 (2009).
[3] R. Rey, J.T. Hynes, PCCP 14, 6332 (2012).
[4] J. Petersen, K.B. Moller, R. Rey, J.T. Hynes, 10.1021/jp308648u J. Phys. Chem. B.
TITLE: Molecular energy transfer in liquid water
DATE / PLACE: 11am 29/11/2012, sala de reunions B5-211
ABSTRACT:
Liquid water is the matrix of crucial processes that involve the molecular excitation of the surrounding water molecules, or even the direct formation of water molecules in excited states. Understanding the mechanisms by which excess molecular energy is channelled back to equilibrium is thus of fundamental interest. We show here, for the case of neat water, how this can be done via a detailed analysis of energy fluxes between molecular modes [1,2,3,4].
Such analysis is carried out through the computation of the various contributions to the power and the work on the initially excited mode. In this way one can determine, for instance, which percentage of vibrational energy flows into self-rotation through centrifugal coupling, and to which particular axis this flow is maximal [1,2]. Moreover the spatial extent of energy flow into other water molecules can be ascertained as well, together with the specific molecular modes (translational, rotational) to which excess energy is transferred [3,4]. To this end, classical nonequilibrium MD runs are conducted for neat liquid water, so that at the initial time either: (a) the bend mode of a single flexible water molecule is excited or, (b) a purely rotational excitation is created for a single rigid molecule.
Bend relaxation is found to be dominated by energy flow to the hindered rotation of the bend excited water molecule, due to a 2:1 Fermi resonance for the centrifugal coupling between the water bend and rotation. The remaining energy flow from the excited water bend is dominated by transfer to rotations of the first hydration shell. The later statement is also valid for the flow ensuing direct rotational excitation of the central water molecule.
The basic conclusion is that about ninety per cent of the initial excess energy is channeled through rotational energy of immediate neighbours, for both vibrational and rotational excitations.
[1] F. Ingrosso, R. Rey, T. Elsaesser, J.T. Hynes, J. Phys. Chem A 113, 6657 (2009).
[2] R. Rey, F. Ingrosso, T. Elsaesser, J.T. Hynes, J. Phys. Chem A 113, 8949 (2009).
[3] R. Rey, J.T. Hynes, PCCP 14, 6332 (2012).
[4] J. Petersen, K.B. Moller, R. Rey, J.T. Hynes, 10.1021/jp308648u J. Phys. Chem. B.
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