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Nanotubed titanic acid (H 2 Ti 2 O 4 (OH) 2 ) was prepared from nanotubed sodium titanate (Na 2 Ti 2 O 4 (OH) 2 ) by an ion exchange reaction in a pH = 1 HCl solution. The effect of annealing temperature on the morphology, structure and photocatalytic behavior of nanotubed H 2 Ti 2 O 4 (OH) 2 was studied by means of TEM, XRD, DTG, DSC, BET and ESR. The results showed that nanotubed H 2 Ti 2 O 4 (OH) 2 is thermally unstable. Its dehydration consists of two steps. In the first-step dehydration, single-electron-trapped oxygen vacancies (SETOVs) were generated. Accompanying the second-step dehydration, the transition of crystal form from orthorhombic system to anatase took place, at the same time the nanotubes broke. At T > 300 • C, when the SETOV concentration greatly increased, the interaction between SETOV happened. (V O o ) x formed could play the role of recombination center of photogenerated e − -h + and make the photocatalytic behavior of TiO 2 (anatase, obtained from 500 • C-treated nanotubed H 2 Ti 2 O 4 (OH) 2 ) to become bad.

The dynamic process of intense 50 fs laser ablation of aluminum is investigated by ultrafast time-resolved microscopy. A stripe pattern preceding phase explosion is clearly seen in the shadowgraph of 1 ns time delay. Intermittent material ejections are observed within the ejected plume after 2.5 and 7 ns time delay, respectively, which may be attributed to the material response to the generation of an extremely strong thermoelastic wave. Similar processes are also recorded in the ablation of silicon and glass samples, except for the glass samples, the intermittent material ejections are not found.