Transparent sidewall

Sonication of SWCNTs in an aqueous solution of a pyrene-carrying ammonium ion (Fig. 1.13) gave a transparent dispersion/solution of the tubes. The dispersion was characterized by TEM, UV/Vis absorption, fluorescence and 1H NMR spectroscopy and the results evidenced the interaction of the tube sidewalls with the pyrene moiety [212]. 

Because of the addition of the returning wave to the bulk intensity, the intensity drop-off is less steep for more reflective substrates (see Fig. 9.14). This implies that resists will have straighter sidewalls on reflective substrates, provided the standing waves can be diffused out. Also, resists to be used on nonreflective substrates need to be more transparent than those used for highly reflective materials such as aluminum (see Fig. 9.14). 

Titanium dioxide (TiOj) is an important pigment that produces white colors. It has a high refractive index (n 2.6), which leads to significant light scattering. It is added to synthetic fibers in the manufacturing process to make them seem white rather than translucent or transparent. It is also used with photographic paper and white tire sidewalls. 

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