Evidence for a two-step mechanism in electronically selective single-walled carbon nanotube reactions

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Year: 2005
Type of Publication: Article
  • M. L. Usrey, M. S. Strano E. S. Lippmann
Journal: Journal of the American Chemical Society Volume: 127
Number: 46
Month: NOV 23 2005
PT: J; TC: 69; UT: WOS:000233445900037
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 (iota = 2.4 min). A slower, covalent reaction is tracked using the time-dependent increase in the disorder mode in Raman (iota = 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.