High-pressure optical study of bromine-doped single-walled carbon nanotube films

We present a high‐pressure optical spectroscopy study on single‐walled carbon nanotubes (SWCNTs) doped with bromine using nitrogen as pressure transmitting medium. Bromine‐doped SWCNTs (Br‐SWCNTs) with different doping levels were prepared by the gas phase method and characterized by optical and Raman spectroscopy. The absorption and Raman spectra clearly reveal the effects of charge doping by bromine. Like for pristine SWCNTs, the absorption bands of Br‐SWCNTs show a red shift under pressure. Anomalies in the pressure‐induced relative frequency shift indicate structural changes in the nanotubes. The results are compared with those for empty nanotubes.