Fig. 1: Simplified molecular energy diagram for a molecule undergoing laser-induced fluorescence.

Fig. 1: Simplified molecular energy diagram for a molecule undergoing laser-induced fluorescence.

Laser-induced fluorescence (LIF) and planar-LIF (PLIF) are established techniques for species-specific imaging of gas temperature, pressure, or composition along a laser beam or sheet. LIF occurs when a molecule absorbs laser light and then emits a photon(s) as it relaxes back to equilibrium (Fig. 1). The fluorescence is imaged by a camera or detector to acquire spatially resolved information about the local gas conditions.

Usually, LIF is performed at ultraviolet or visible wavelengths using high-power lasers to image combustion radicals (e.g., OH, CH) or tracer molecules (e.g., acetone, toluene) seeded into flows.

Fig. 2: IR-PLIF video of carbon dioxide in a bifurcated jet. See Goldenstein et al., Applied Physics B (2015) for more information.

The Goldenstein Group is interested in advancing the development of infrared (IR) LIF and PLIF diagnostics to enable imaging of chemical species that established techniques cannot easily detect (e.g., CO2, CO, H2O). Fig. 2 shows an example of high-speed video of IR-PLIF.

Research is ongoing in:

  1. Infrared photophysics and spectroscopy

  2. Infrared imaging

  3. Optical engineering

  4. Signal processing