Fitting Single-Walled Carbon Nanotube Optical Spectra

Moritz Pfohl; Daniel D Tune; Arko Graf; Jana Zaumseil; Ralph Krupke; Benjamin S Flavel

doi:10.1021/acsomega.6b00468

Fitting Single-Walled Carbon Nanotube Optical Spectra

ACS Omega. 2017 Mar 31;2(3):1163-1171. doi: 10.1021/acsomega.6b00468. Epub 2017 Mar 27.

Authors

Moritz Pfohl¹, Daniel D Tune², Arko Graf³, Jana Zaumseil³, Ralph Krupke¹, Benjamin S Flavel⁴

Affiliations

¹ Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany; Institute of Materials Science, Technische Universität Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
² Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany; Centre for Nanoscale Science and Technology, Flinders University, GPO Box 2100, 5042 Adelaide, Australia.
³ Institute for Physical Chemistry, Universität Heidelberg , Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
⁴ Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT) , P.O. Box 3640, 76021 Karlsruhe, Germany.

Abstract

In this work, a comprehensive methodology for the fitting of single-walled carbon nanotube absorption spectra is presented. Different approaches to background subtraction, choice of line profile, and calculation of full width at half-maximum are discussed both in the context of previous literature and the contemporary understanding of carbon nanotube photophysics. The fitting is improved by the inclusion of exciton-phonon sidebands, and new techniques to improve the individualization of overlapped nanotube spectra by exploiting correlations between the first- and second-order optical transitions and the exciton-phonon sidebands are presented. Consideration of metallic nanotubes allows an analysis of the metallic/semiconducting content, and a process of constraining the fit of highly congested spectra of carbon nanotube solid films according to the spectral weights of each (n, m) species in solution is also presented, allowing for more reliable resolution of overlapping peaks into single (n, m) species contributions.