Strong amplification of mid-infrared radiation absorption in nanotube-confined water

Energy absorption on a nanometer scale is vital for biochemical and climate systems. This paper reports that a two times amplification in absorption efficiency of mid-infrared (MIR) radiations can be achieved by water molecules confined in carbon nanotubes with a small radius compared to the bulk water absorption. This absorption enhancement is closely associated with the configurational change of water molecules into a unidirectional alignment under the nanotube confinement, which greatly augments the transition probability concerning the MIR absorption. In addition, the effect of confinement due to a (6,6) carbon nanotube is found to be very robust, equivalent to that of a 5 V/nm static electric field. These findings can be used to design energy-efficient nanodevices to modulate the microclimate variables by converting the redundant ambient MIR irradiation into the prompt heat conduction and are instructive for understanding the specific functioning of relevant biological channels.