Photothermal conversion dynamics in femtosecond and picosecond discrete laser etching of Cu-phthalocyanine amorphous film analysed by ultrafast UV-VIS absorption spectroscopy

Citation
Y. Hosokawa et al., Photothermal conversion dynamics in femtosecond and picosecond discrete laser etching of Cu-phthalocyanine amorphous film analysed by ultrafast UV-VIS absorption spectroscopy, J PHOTOCH A, 142(2-3), 2001, pp. 197-207
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
ISSN journal
1010-6030 → ACNP
Volume
142
Issue
2-3
Year of publication
2001
Pages
197 - 207
Database
ISI
SICI code
1010-6030(20010914)142:2-3<197:PCDIFA>2.0.ZU;2-Q
Abstract
Novel etching of Cu-phthalocyanine (CuPc) amorphous film which is character istic of ultrashort laser irradiation was successfully confirmed by tuning Ti:Sapphire laser (780 nm) to 150 fs, 250 ps, or 100 ns, and the primary pr ocesses were investigated by fs pump-fs probe and ps pump-fs probe spectros copic measurements. In the fs and ps laser ablation, we have found discrete laser etching in that the etch depth becomes constant and is independent o f laser fluence above the ablation threshold, although gradual (normal) etc hing, in which the etch depth increase continuously with the fluence above ablation threshold, was observed in the ns laser ablation. The transient ab sorption spectral measurements reveal the nonlinear photothermal conversion processes, corresponding to exciton-exciton annihilation and cyclic multip hotonic absorption. Their time evolutions during and after the excitation p ulse duration were considered and elucidated to depend strongly on the exci tation pulse width. On the basis of these results, we discuss an ablation m echanism for the ps and fs ablation that the temperature elevation bringing about transient high pressure is responsible for discrete etching. (C) 200 1 Published by Elsevier Science B.V.