Ž . Spectrochimica Acta Part B 56 2001 753776 Optical emission spectroscopy and modeling of plasma produced by laser ablation of titanium oxides  A. De Giacomo a,b,  , V.A. Shakhatov c , O. De Pascale c a Dipartimento di Chimica, Uni  ersity of Bari, Via Orabona 4, Bari, Italy b Centro di studio per la chimica dei plasmi del CNR, Via Orabona 4, Bari, Italy c Centro Laser, S.P. per Casamassima, km.3-70010 Valenzano, Bari, Italy Received 12 October 2000; accepted 23 April 2001 Abstract In the present study, the time evolution of electron number density, of electron, atom and ion temperatures, of plasma produced by KrF excimer laser ablation of titanium dioxide and monoxide targets, are investigated by temporally and spatially resolved optical emission spectroscopy over a wide range of laser fluence from 1.7 to 6 J cm 2 , oxygen pressures of 10 2  10 1 torr and in a vacuum. A state-to-state collisional radiative model is proposed for the first time to interpret the experimental results at a distance of 0.6 mm from the target surface, in vacuum and for a time delay from 100 to 300 ns from the beginning of the laser pulse. In particular, we concentrate our attention on problems concerning the existence of the local thermodynamic conditions in the laser-induced plasma and deviation from them, as observed in our experiment. The numerical model proposed for calculating the electron number density and the population densities of atoms and ions in excited states give good quantitative agreement with the experimental results of the optical emission spectroscopy measurements.  2001 Elsevier Science B.V. All rights reserved. Keywords: Laser induced plasma; Local thermodynamic equilibrium; Optical emission spectroscopy; State-to-state collisional radiative model; Titanium oxides  This paper was presented at the 1st International Congress on Laser Induced Plasma Spectroscopy and Applications, Pisa, Italy, October 2000, and is published in the Special Issue of Spectrochimica Acta Part B, dedicated to that conference.  Corresponding author. Tel.: 39-080-4674314; fax: 39-080-4674457. Ž . E-mail address: adg@mail.centrolaser.it A. De Giacomo . 0584-854701$ - see front matter  2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 5 8 4 - 8 5 4 7 01 00224-5