Stark Effect Tunable Terahertz Transitions in Finite Carbon Chains

Highly aligned, long polyynic chains terminated with gold clusters have been synthesized, and their use for tunable terahertz (THz) emitters is proposed. A tight‐binding model (which is arguably best suited to describe edge states in the limit of strong optical pumping) is employed to calculate the optical selection rules of gold‐capped finite‐size polyyne chains subjected to an applied electric field. The magnitude of the edge‐state gap and the strength of optical transitions across it are tunable via the Stark effect. For sufficiently long chains, electric‐field‐tunable dipole transitions between edge states occur in the highly sought‐after THz frequency range.