Analyses of the TiO-gamma system for temperature measurements in a laser-induced plasma

Emission spectra of TiO molecules in the spectral range from 700 to 720 nm have been recorded during pulsed-laser ablation of Ti in a low-pressure O-2 atmosphere. The observed emission bands belong to the Deltav = 0 and Delta v = +1 vibrational sequences of the gamma -system (A(3)Phi -X(3)Delta) of T iO. According to the relative high temperatures in the laser-induced plasma of the order of 10(4) K, vibrational and rotational states with large quan tum number are populated. Thus, the recorded spectra result from the superp osition of more than 10(4) rotational lines belonging to 30 different vibra tional bands. For the determination of the rotational and vibrational tempe ratures, the complicated structure of the TiO-gamma emission spectrum has b een reproduced using computer simulations. As a result, the gas kinetic tem perature of the laser-induced plasma has been measured as a function of tim e and space for different O-2 pressures. The temperature measurements are u seful for a better understanding of the chemical processes during thin-film deposition by reactive laser ablac ion. In addition, simple empirical rela tions have been derived for temperature determination from the TiO-gamma em ission spectrum in the range from 3 x 10(2) to 2 x 10(4) K.