Two-dimensional temperature fields are measured in lean and sooting flames by means of two-color laser-induced fluorescence (LIF) imaging that uses seeded NO. Vibrational thermometry is performed by the probing of different vibrational ground-state levels. Spectral properties of the excited transitions within the <i>A</i><sup>2</sup>Σ<sup>+</sup>–<i>X</i><sup>2</sup>Π system are well known from previous studies. The energy difference of 1974 cm<sup>−1</sup> between the (0, 0)<i>Q</i><sub>1</sub> + <i>P</i><sub>21</sub>(33.5) and the (0, 2)O<sub>12</sub>(5.5) lines offers great sensitivity in the temperature range that is relevant for combustion processes. Excitation is possible by use of a tunable KrF excimer laser on its fundamental (248-nm) and Raman shifted (in H<sub>2</sub>, 225-nm) wavelengths. An excitation scheme for instantaneous two-line measurements by use of a single laser is developed. The possibility of single-shot measurements is discussed.
© 2001 Optical Society of America
(140.2180) Lasers and laser optics : Excimer lasers
(280.1740) Remote sensing and sensors : Combustion diagnostics
(300.2530) Spectroscopy : Fluorescence, laser-induced
(300.6360) Spectroscopy : Spectroscopy, laser
Wolfgang G. Bessler, Frank Hildenbrand, and Christof Schulz, "Two-Line Laser-Induced Fluorescence Imaging of Vibrational Temperatures in a NO-Seeded Flame," Appl. Opt. 40, 748-756 (2001)