Characterization of laser ablated species from a La-Ca-Mn-O target by angle- and time-resolved mass spectrometry

The ablation of a La1-xCxMnO3 (La-Ca-Mn-O) target under 532 and 355 nm laser irradiation has been investigated using an angle- and time-resolved quadrupole mass spectrometric technique. At laser fluence of 1.5 J/cm(2), we found the following ablated species: metal atoms La, Ca, Mn and metal ions La+, Ca+, Mn+ as well as various metal oxides LaO, CaO, MnO, LaO2, MnO2, CaO2. Small clusters such as Mn-2, La-2, Mn2O and LaMnO were also observed. The measured time-of-flight (TOF) spectra are well fitted by a Maxwell-Boltzmann distribution with a stream velocity. The estimated kinetic energies of ablated metal ions are found to be in the range of 6-10 eV while those of neutral species range from 0.2 to 0.9 eV. The angular distributions of ablated species show that the ionic species are ejected within a cone shape plume characterized by a cos(n) theta function, while the angular distributions of the neutral species are much broader in comparison with the ionic species. The effect of laser radiation on possible ablation mechanisms are discussed. (Int J Mass Spectrom 178 (1998) 205-212) (C) 1998 Elsevier Science B.V.