Single-slit laser diffractography was used to image the growth of carbon nanotubes. A silicon dioxide slit with a minimum width of 150 μm was prepared and positioned inside a chemical vapor deposition (CVD) reactor in alignment with a laser source. Carbon nanotubes were grown inside the slit width, producing corresponding changes in the diffraction pattern due to the optical opacity of these structures and to their high density and alignment. Changes in the diffraction pattern were recorded and used for the direct measurement of nanotube growth. The results show an exponential increase of length vs time for 45 min experiments, best fit with a double exponential function, which is interpreted in terms of the concurrence of base-growth and tip-growth modes for successive catalyst particles. Scanning electron microscopy confirms the diffractographic data at a high level of precision. The innovation brought by this in situ method to the kinetic study of nanotube synthesis is discussed and compared to a posteriori studies based solely on microscopy for a range of different nanotube lengths.

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V2O5 electronic band structure from cathodoluminescence reveals how lithiation creates octahedral distortion and not oxygen vacancies or conversion reactions.