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We conduct the detailed numerical investigation of a nanomanipulation and nanofabrication technique—thermal tweezers with dynamic evolution of surface temperature, caused by absorption of interfering laser pulses in a thin metal film or any other absorbing surface. This technique uses random Brownian forces in the presence of strong temperature modulation (surface thermophoresis) for effective manipulation of particles/adatoms with nanoscale resolution. Substantial redistribution of particles on the surface is shown to occur with the typical size of the obtained pattern elements of ∼100 nm, which is significantly smaller than the wavelength of the incident pulses used (532 nm). It is also demonstrated that thermal tweezers based on surface thermophoresis of particles/adatoms are much more effective in achieving permanent high maximum-to-minimum concentration ratios than bulk thermophoresis, which is explained by the interaction of diffusing particles with the periodic lattice potential on the surface. Typically required pulse regimes including pulse lengths and energies are also determined. The approach is applicable for reproducing any holographically achievable surface patterns, and can thus be used for engineering properties of surfaces including nanopatterning and design of surface metamaterials. [ABSTRACT FROM AUTHOR]

In this paper, evolution of the size distribution of fine and ultra-fine particles emitted from vehicles on a busy road is investigated experimentally. In particular, several different modes (distinct maxima) of the particle size distribution are investigated as a function of the distance from the road. An unusual and complex evolution of these modes is discovered. In particular, it is demonstrated that some of the modes tend to shift towards smaller particle size, which has never been reported previously. Complex correlation between the modes is determined experimentally. In addition, for the first time, the total number concentration is clearly shown to go through a significant maximum at some distance from the road. This could have significant influence on the assessment of exposure to fine and ultra-fine particles in the vicinity of busy roads. [Copyright &y& Elsevier]