Applied Surface Science, Vol.417, 160-164, 2017
Self-organisation of single-crystals as ripple patterns through laser ablation of ionic salt solutions
Relatively thin (d = 2.5 mu m), diluted (c = 0.001-0.1%wt.) aqueous liquid films of ionic salts (NaCl, K2CrO4) were each irradiated with a single infrared laser pulse (wavelength, lambda = 10.59 mu m, fluence J -100J/cm(2), spot diameter D = 3 mm, irradiation time t = 100 mu s). This approach has induced the formation of hierarchically arranged single crystal ripples near the edge of the laser impact zone. Depending on the ionic salt concentration and beta angle of incidence in respect to the surface, the number of ripples varied between 5 and 100 and their interspacing between a few micrometres and hundreds of micrometres. In addition to ripples, K2CrO4 salts form beside ripples, parallel, long and thin single crystals, which orthogonally intersect the ripples to form a rectangular crystal grid. In addition to the theoretical gain, crystals have potential applications in optoelectronics and sensors. (c) 2017 Published by Elsevier B.V.