S. Link et al., Laser photothermal melting and fragmentation of gold nanorods: Energy and laser pulse-width dependence, J PHYS CH A, 103(9), 1999, pp. 1165-1170
We studied the shape transformation (by use of TEM and optical absorption s
pectroscopy) of gold nanorods in micellar solution by exposure to laser pul
ses of different pulse width (100 fs and 7 ns) and different energies (mu J
to mJ) at 800 nm, where the longitudinal surface plasmon oscillation of th
e nanorods absorb. At moderate energies, the femtosecond irradiation melts
the nanorods to near spherical particles of comparable volumes while the na
nosecond pulses fragment them to smaller near-spherical particles. At high
energies, fragmentation is also observed for the femtosecond irradiation. A
mechanism involving the rate of energy deposition as compared to the rate
of electron-phonon and phonon-phonon relaxation processes is proposed to de
termine the final fate of the laser-exposed nanorods, i.e., melting or frag
mentation.