Publications in Scientific Journals:
S. Bashir, M. Rafique, W. Husinsky:
"Surface topography of ultrashort laser-irradiated CaF2";
Radiation Effects and Defects in Solids,
A single-crystal CaF2 (111) was irradiated with single and multiple laser (Ti:sapphire, 800 nm, 25 fs) shots
at fluences ranging from 0.25 to 1.5 J cm−2. In this fluence regime, a single laser pulse usually leads to
typical bump-like features ranging from 200 nm to 1.5μm in diameter and 10-50 nm in height. These
bumps are related to compressive stresses due to a pressure build-up induced by fast laser heating and their
subsequent relaxation. When CaF2 is irradiated with successive (in our case 20) shots at a laser fluence of
1.5 J cm−2, nanocavities at the top of the microbumps are observed. The formation of these nanocavities
is regarded as an explosion and is attributed to the explosive expansion generated by shock waves due
to laser-induced plasma after the nonlinear absorption of the laser energy by the material. Such kinds of
surface structures at the nanometre scale could be attractive for nanolithography.
ablation; CaF2; defects
Created from the Publication Database of the Vienna University of Technology.