New seeding methodology for two-line atomic fluorescence Part I: Non-reacting flow

Abstract

This paper demonstrates the feasibility of using pulsed laser ablation to generate neutral indium atoms at ambient pressure and temperature. The indium atoms can be used as the thermometry species for the two-line atomic fluorescence (TLAF) method, which is emerging as a useful laser-based thermometry technique in sooty environments. The ablation of an indium rod is achieved with the use of a focused, beam from the second harmonic of a pulsed Nd:YAG laser onto an indium rod at approximately atmospheric pressure. The neutral indium atoms generated by the pulsed laser ablation method are found to be sufficiently stable to allow them to be generated upstream from the from the measurement region and survive a convection time of at least 30 seconds before entering the measurement region in the flame. This offers a number of important advantages for the TLAF technique over the previously established seeding methodology employing a fine mist of indium chloride solution, namely greater operating range and increased flexibility.