Special Topic Issue on the Theme of
Phototransformation of Alkanethiol-derivatized Noble
Chil Seong Ah, Hyouk Soo Han, Kwan Kim, and Du-Jeon
*School of Chemistry and Center for
Molecular Catalysis, Seoul National University, Seoul 151-742, Korea
Abstract: Photon-initiated shape transformation
of n-alkanethiol-derivatized noble metal nanoparticles has been studied
with variations of metal, alkanethiol, and solvent. Silver nanoparticles
undergo fragmentation upon irradiation while gold ones barely do. Silver/gold
composite particles follow the case of silver with a reduced efficiency.
The efficiency decreases as alkanethiol length or solvent dipole moment
increases. Following the conduction of thermalized photon energy, alkanethiol
can dissociate in a period of heat dissipation, and some of dethiolated
particles fragment within the recombination time. Prior to the thermal
conduction, shape transformation via melt and vaporization also occurs
for both metals but this effect is less apparent for silver because
of more notable fragmentation followed. The difference in the transformation
of two metals is ascribed to the differences in work function, oxidation
potential, atomization enthalpy, and particle size. Smaller fragmentation
efficiency with more polar solvent or longer alkanethiol is attributed
mainly to relatively smaller dissociation rate compared with heat dissipation
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