Figure 2.

a UV–visible absorption spectra and corresponding photos of colloidal titanium oxide solutions (inset) produced by PLAL under specified laser parameters 1 to 4 (cf. Table 1) and then settled for 1 week, showing broadened absorption below 400 nm for the samples 1 to 3 fabricated under relatively low power density, and sharp absorption below ca. 230 nm for sample 4 by the highest power density of 1.4 × 1011W/cm2. b and c Optical micrographs under open polarizer (left) and crossed polarizers (right) for the deposit in samples 2 (top panel) and 4 (bottom panel) showing titanium oxide nanocondensates were assembled as particles and tubes, respectively

Huang et al. Nanoscale Research Letters 2010 5:972-985   doi:10.1007/s11671-010-9591-4