FEMTOSECOND LASER-ABLATION OF SAPPHIRE - TIME-OF-FLIGHT ANALYSIS OF ABLATION PLUME

Time-of-flight mass spectrometry has been used to investigate the mass and velocity distributions of positive ions produced on laser ablatio n of sapphire with ultrashort (200 fs) laser pulses at a wavelength of 790 nm. Aluminium and oxygen ions were observed with the proportion o f singly and doubly charged oxygen ions increasing with increasing num ber of laser shots Fur a given laser fluence. The ions have extremely high kinetic energies which is attributed to Coulomb explosion from ch arged defect sites. (C) 1998 Elsevier Science B.V.