Evaluation of morphology and size distribution of silicon and titanium oxide nanoparticles generated by laser ablation

Nanometer-sized particles of silicon and titanium oxide were generated by irradiating solid targets using a nanosecond pulsed-Nd: YAG laser in a low pressure atmosphere. A low pressure differential mobility analyzer (LP-DMA) was used to classify the size of the generated particles. The LP-DMA and electron microscopes (SEM and TEM) were used to measure the change in the size distribution and morphology of the generated particles with laser power density and system pressure. The size distribution of both silicon and titanium oxide ranged from two to one hundred nanometers in diameter depending on the laser power density and pressure. From the high resolution TEM observation and electron diffraction, it was found that the generated titanium oxide nanoparticles were composed of a 'core' of faceted metallic single crystals with an oxide layer 'shell'.