Quantum bottlenecks and unidirectional energy flow in molecules

Abstract

Quantum mechanical effects can enable energy to flow more efficiently in one direction along a molecule than in others. Ultrafast spectroscopic experiments on substituted benzenes [J. Phys. Chem. B 117, 10898 (2013)] reveal such an asymmetry in the flow of vibrational energy between the two chemical groups of the molecule, i.e., between the phenyl and the substituent. We examine theoretically energy flow in toluene, one of the substituted benzenes probed in the recent experiments, and show that quantum mechanical bottlenecks give rise to a preferred direction of energy flow in this molecule.

Vibrational energy transport in molecules and the statistical properties of vibrational modes

“…Of course there are additional sources of scattering at molecular interfaces that can give rise to resistance, in particular at the boundary between the molecule and solid or other molecules [49,[71][72][73][74][75][76][77][78]. It would be interesting to examine the modes of the surfaces atoms of the solid layer and the molecule combined to explore the correspondence between statistical properties of those modes and vibrational energy transport dynamics.…”

Molecules and the Eigenstate Thermalization Hypothesis

“…The study of thermal conduction through molecules of order 10 to 1000 atoms [ 14 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 ] has been motivated by the more general desire to control thermal transport at the nanoscale towards the design of nanoscale devices [ 92 , 93 ], small composite materials in which interfaces often mediate heat flow. Work on this problem has been driven by potential applications that include avoiding high concentrations of heat in small devices [ 92 , 93 ], thermoelectric applications [ 94 ], the possibility of thermal rectification at the nanoscale [ 61 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ], and the contribution of thermal gradients to electron transfer [ 62 , 69 , 70 ].…”

Molecules and the Eigenstate Thermalization Hypothesis

“…The study of thermal conduction through molecules from of order 10 to 1000 atoms [14,[73][74][75][76][77][78][79][80][81][82][83][84] has been motivated by the more general desire to control thermal transport at the nanoscale towards the design of nanoscale devices [85,86], small composite materials in which interfaces often mediate heat flow. Work on this problem has been driven by potential applications that include avoiding high concentrations of heat in small devices [85,86], thermoelectric applications [87], the possibility of thermal rectification at the nanoscale [57,[88][89][90][91][92][93], and the contribution of thermal gradients to electron transfer [58,65,66].…”