Effects of capping thiols on the laser-induced fusion of gold nanoparticles and deposition onto glass substrates in cyclohexane

On irradiation with pulsed 532-nm laser light, dodecanethiol (DT)-capped gold nanoparticles (DT-Au) aggregate and fuse in organic solvents. As a result of particle destabilization, the particles are deposited onto a glass substrate immersed in a colloidal cyclohexane solution. Generally, the properties of gold nanoparticles depend strongly on the surface conditions of the particles. In this report, small amounts of immobilized DT molecules were replaced with 1,6-hexanedithiol (HD) molecules, giving gold nanoparticles capped with DT and HD, denoted as (DT + HD)-Au. The amount of HD in (DT + HD)-Au was determined to be ∼6% by elemental analysis. Interestingly, the absorption spectra of DT-Au and (DT + HD)-Au indicated that both particles have similar stabilities in colloidal solution. Despite this, the activities of these gold nanoparticles after laser irradiation differed dramatically. When (DT + HD)-Au was used instead of DT-Au, the degree of growth and deposition of gold nanoparticles was accelerated and the deposited particles were huge, reaching sizes of several hundreds of nanometers.