Time-Resolved Quadrupole Mass Spectrometric Studies on Pulsed Laser Ablation of TiO₂

Abstract

Pulsed laser ablation of TiO₂ at 355 nm and 532 nm has been investigated using an angleand time-resolved quadrupole mass spectrometric technique. The major ablated species include O (m/e = 16), O₂ (m/e = 32), Ti (m/e = 48), TiO (m/e = 64) and TiO₂ (m/e = 80). The time-of-flight (TOF) spectra of ablated species are measured for the ionic and neutral ablated species, and they can be fitted by a Maxwell – Boltzmann (M – B) distribution with a center-of-mass velocity. The measured angular distributions of the ionic species (O⁺ and Ti⁺) and the neutral species (O and Ti) can be fitted with cos⁡nθ and a cos⁡θ + (1−a)cos⁡nθ, respectively. In addition, a continuous wave oxygen molecular beam is introduced into the ablated plume, and the enhancement of the signal intensities of TiO is observed. It implies that the ablated Ti atoms/ions species can react with ambient oxygen molecules in the gas phase. In the meanwhile, the physicochemical mechanism of pulsed laser ablation of TiO₂ is discussed.