Raman spectroscopy of carbon nanohoops

We present the Raman spectra for [n]Cycloparaphenylenes ([n]CPPs) of different sizes. A plethora of Raman modes are observed in these spectra, including modes that are analogous to those of the carbon nanotubes (CNTs) such as G-band, as well as Raman peaks that are unique for carbon nanohoops. In addition, we have calculated the theoretical Raman spectra of [n]CPPs for n = 4–20 using density functional theory (DFT), which are then compared to the experimental results for the assignment of different modes. The Raman peak positions are seen to be dependent on the size of the nanohoop from both the experimental and the calculated results.