title: Evidence for a two-step mechanism in electronically selective single-walled carbon nanotube reactions.
abstract: Covalent and noncovalent chemistries that are selective to single-walled carbon nanotubes of a particular electronic type have become increasingly important for electronic structure separation and on-chip modification of nanoelectronic devices. By monitoring transient Raman spectroscopy and photoluminescence (PL) during a reaction with 4-chlorobenzene diazonium in aqueous solution, evidence for a characteristic two-step mechanism with two distinct time constants is uncovered. A long-lived intermediate selectively and noncovalently binds and partially dopes the nanotube surface (tau = 2.4 min). A slower, covalent reaction is tracked using the time-dependent increase in the disorder mode in Raman (tau = 73 min). The transient Raman and PL data are well described using a series of two first-order reactions. The covalent bonding step can be deactivated by changing the structure of the surfactant adsorbed phase, further supporting the mechanism.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois--Urbana/Champaign, Urbana, Illinois 61801, USA.
authors.forename: Monica L
authors.initials: ML
authors.lastname: Usrey
authors.forename: Ethan S
authors.initials: ES
authors.lastname: Lippmann
authors.forename: Michael S
authors.initials: MS
authors.lastname: Strano