An angle-resolved time-of-flight mass spectrometric study of pulsed laser ablated Ta2O5

Pulsed laser ablation of a Ta2O5 target at 532 nm has been investigated using an angle-resolved time-of-flight quadrupole mass spectrometric method. Mass and velocity distributions of the ionic and neutral ablated species were measured. The major ablated species, O (m/e = 16), O-2 (m/e = 32), Ta (m/e = 181), TaO (m/e = 197), and TaO2 (m/e = 213) were observed at a laser fluence of 0.7 J cm(-2), and the intensities of neutral species were found to be higher than those of the ionic species. The time-of-flight spectra of ablated species were fitted by a Maxwell-Boltzmann distribution with a center-of-mass velocity. The angular distributions of the ionic and neutral ablated species can be fitted with cos(n) theta (n = 15) and 0.25 cos theta + 0.75 cos(n) theta (n = 15), respectively. The laser fluence had no obvious influence on the translational energies of the ablated species. In addition, a continuous wave oxygen molecular beam was introduced into the ablated plume, and the enhancement of the intensities of the TaO and TaO2 signals was observed. This result implies that the reactions of ablated Ta-containing species with ambient oxygen molecules in the gas phase play an important role:in the pulsed laser deposition process. (C) 1998 American Institute of Physics. [S0021-8979(98)03311-8].