Optical Property Tuning of Single-Wall Carbon Nanotubes by Endohedral Encapsulation of a Wide Variety of Dielectric Molecules
Jeffrey Fagan, Jan Obrzut, sofie cambre, wim wenseleers, bea botka, jochen campo
Specific and tunable modification to the optical properties of single-wall carbon nanotubes (SWCNTs) is demonstrated through the direct encapsulation into the nanotube interior of guest molecules with widely varying static dielectric constants. Filled through simple ingestion of the guest molecule prior to SWCNT dispersion, each SWCNT population is demonstrated to display a robust modification to absorbance, fluorescence and Raman spectra. Well over thirty distinct compounds, covering static dielectric constants from 1.8 to 109, are inserted in large diameter SWCNTs, and more than ten compounds in small diameter SWCNTs, demonstrating for the first time that the general effect of filler dielectric on the nanotube optical properties is a monotonic energy reduction (red- shifting) of the optical transitions with increased magnitude of the dielectric constant. Systematic fitting of the two-dimensional fluorescence-excitation and Raman spectra additionally enables determination of the critical filling diameter for each molecule and distinguishing of overall trends from specific guest-host interactions. Comparison to predictions from existing theory are presented, and specific guest molecule/SWCNT chirality combinations that lead to effects disobeying the general trend and theory are identified. In addition to spectral shifts, the filling with dielectric molecules also reveals a general increase of the fluorescence intensity and line narrowing towards low dielectric constants, with e.g., (long) linear alkane filled SWCNTs exhibiting emission intensities approaching those of empty SWCNTs. These results demonstrate both a new degree of exploitable modulation in the optical properties of SWCNTs, and provide a foundation for examining higher order effects, such as due to non-bulklike molecule stacking, in host-guest interactions in well controlled nanopore size materials.
, Obrzut, J.
, Cambre, S.
, Wenseleers, W.
, botka, B.
and campo, J.
Optical Property Tuning of Single-Wall Carbon Nanotubes by Endohedral Encapsulation of a Wide Variety of Dielectric Molecules, ACS Nano, [online], https://doi.org/10.1021/acsnano.0c08352
(Accessed December 3, 2023)