The bending modulus of individual carbon nanotubes from aligned arrays grown by pyrolysis was measured by in situ electromechanical resonance in transmission electron microscopy (TEM). The bending modulus of nanotubes with point defects was $\sim 30\mathrm{GPa}$ and that of nanotubes with volume defect was 2–3 GPa. The time-decay constant of nanotube resonance in a vacuum of ${10}^{-4\mathrm{}}\mathrm{Torr}$ was $\sim 85\mu \mathrm{s}$. A femtogram nanobalance was demonstrated based on nanotube resonance; it has the potential for measuring the mass of chain-structured large molecules. The in situ TEM provides a powerful approach towards nanomechanics of fiberlike nanomaterials with well-characterized defect structures.

• Received 7 February 2000

DOI:https://doi.org/10.1103/PhysRevLett.85.622