Measuring the Uniaxial Strain of Individual Single-Wall Carbon Nanotubes: Resonance Raman Spectra of Atomic-Force-Microscope Modified Single-Wall Nanotubes
Raman spectroscopy is used to measure the strain in individual single-wall carbon nanotubes, strained by manipulation with an atomic-force-microscope tip. Under strains varying from 0.06% 1.65%, the in-plane vibrational mode frequencies are lowered by as much as 1.5% (40 cm-1), while the radial breathing mode (RBM) remains unchanged. The RBM Stokes/anti-Stokes intensity ratio remains unchanged under strain. The elasticity of these strain deformations is demonstrated as the down-shifted Raman modes resume their prestrain frequencies after a nanotube is broken under excessive strain.