Triplet absorption in carbon nanotubes: a TD-DFT study

摘要

We predict properties of triplet excited states in single-walled carbonnanotubes (CNTs) using a time-dependent density-functional theory (TD-DFT). Weshow that the lowest triplet state energy in CNTs to be about 0.2-0.3 eV lowerthan the lowest singlet states. Like in $\pi$-conjugated polymers, the lowestCNT triplets are spatially localized. These states show strong opticalabsorption at about 0.5-0.6 eV to the higher lying delocalized triplet states.These results demonstrate striking similarity of the electronic featuresbetween CNTs and $\pi$-conjugated polymers and provide explicit guidelines forspectroscopic detection of CNT triplet states.