Tuesday, July 30, 2013

1307.7288 (Kristen Kaasbjerg et al.)

Charge-carrier-induced frequency renormalization, damping and heating of
vibrational modes in nanoscale junctions

Kristen Kaasbjerg, Tomáš Novotný, Abraham Nitzan
In nanoscale junctions the interaction between charge carriers and the local vibrations results in renormalization, damping and heating of the vibrational modes. We develop a nonequilibrium Green's functions based theory to describe such effects. Applying our theory to a generic junction model with an off-resonant electronic level, we discover a strong bias dependence of the frequency renormalization and vibrational damping in junctions with intermediate values of the coupling to the leads that is accompanied by pronounced nonlinear vibrational heating. Furthermore, combining our theory with ab-initio calculations we show that the bias dependence of the Raman shifts and linewidths observed experimentally in an OPV3 junction [D. Ward et al., Nature Nano. 6, 33 (2011)] may be explained by a combination of dynamic carrier screening and molecular charging.
View original: http://arxiv.org/abs/1307.7288

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