[18p-E307-1~15] 17.1 Carbon nanotubes & other nanocarbon materials

[18p-E307-7] Density Measurement for Carbon Nanotube Thin-film Grown on Flat Substrates

〇Kazuhiko Omote¹, Raita Hirose¹, Kei Noda², Naoya Imayama², Ryo Endo³, Naoyuki Sugiyama³ (1.Rigaku Corp., 2.Keio Univ., 3.Toray Research Center)

Keywords:Carbon nanotube, density measurement, X-ray transmittance

We have proposed an X-ray absorption method for measuring density of vertically-aligned carbon nanotubes (VACNTs) grown on flat substrates. X-ray photons can penetrate through the thin film parallel to the surface direction, even the substrate is few millimeters in width. The transmitted X-rays are detected by a submicron resolution X-ray camera, which enables to distinguish among the thin film, substrate, and vacuum areas in the observed X-ray image. Thickness of the film should be more than ten micrometers due to the refracted X-ray at the thin film surface degrades the spatial resolution of the image. We have measured several samples with film thickness are from few-tens micrometers to several hundred micrometers. When the sample surface is aligned just parallel to the penetrating direction of X-rays, we can clearly observe X-ray absorption rate of the thin film area with comparing X-ray intensity comes through vacuum area. The X-ray mass attenuation coefficients m/rfor every element are easily to find in the International Table of Crystallography with good accuracy. The film density can be calculated from the observed absorption rate if the elemental composition of the film material is known. The obtained densities of VACNTs are less than 0.1 g/cm³, which is much lower than that of bulk carbon materials.