Flexural vibration spectra of carbon nanotubes measured using laser Doppler vibrometry.

Laser Doppler vibrometry is used to measure the thermal vibration spectra of individual multiwalled carbon nanotubes (MWNTs) under ambient conditions. Since the entire vibration spectrum is measured with high frequency resolution, the resonant frequencies and quality factors of the MWNTs are accurately determined, allowing for estimates of their elastic moduli. Because the diameters of the MWNTs studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate values for the smallest diameter nanotube or nanowire whose vibration can be measured in this way.