Laser Synthesis of Gold Nanochains from Hydrochloroauric Acid Aqueous Solutions

The dynamics of the reduction of hydrochloroauric acid (HAuCl 4 ) aqueous solutions and the formation and disintegration of gold nanoparticles under high-intensity irradiation by Ti׃Al 2 O 3 laser pulses (τ = 130 fs, f = 1 kHz, N = 6 × 10 4 –3 × 10 6 pulses, average radiation power of 0.8 W) has been investigated by optical absorption spectroscopy. This high-intensity irradiation is found to cause formation (both during irradiation and after it), along with single gold nanoparticles several ten nanometers in diameter, elongated (chain) submicron structures, consisting of individual nanoelements of different shape. Specific features of the mechanisms of formation and evolution of nanostructures, caused by the multiphoton ionization of a liquid, its heating, and modification of nanostructures as a result of intense impact of an ultrashort laser pulse, as well as liquid heating by radiation with a high average power, are discussed.