American Institute of Aeronautics and Astronautics 1 Characterization of a Perfluorinated Ketone for LIF Applications Jonas P R Gustavsson * and Corin Segal † Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 A perfluorinated ketone, 2-trifluoromethyl-1,1,1,2,4,4,5,5,5-nonafluoro-3-pentanone, has been investigated to determine several physical and spectroscopic properties. It was found to exhibit fluorescence similar to that of acetone, emitting over the 360-550 nm range with a peak near 420 nm when excited at 355 nm. This compound's emission is nearly unaffected over a wide range of temperature and pressure in an argon bath gas. Its fluorescence efficiency was found to be three times higher than that of acetone. Combined with low reactivity and thermal stability up to 500°C, this makes the material an excellent tracer for flow applications near critical conditions. Nomenclature P = pressure P c = critical pressure P R = reduced pressure, P/P c T = temperature T c = critical temperature T R = reduced pressure, T/T c V = molar volume λ = wavelength µ = dynamic viscosity ν = kinematic viscosity ρ = density I. Introduction HE molecular structure of the perfluorinated ketone discussed in the present paper, 2-trifluoromethyl- 1,1,1,2,4,4,5,5,5-nonafluoro-3-pentanone, also known as FK-5-1-12, and referred to as "fluoroketone" for brevity herein, is shown in Figure 1. This fluoroketone has several interesting features that make it an important material for research: ♦ High vapor pressure at ambient pressure – making the fluoroketone a good model for studies of the break-up and mixing of volatile fuels and enabling high seeding densities. ♦ Low critical pressure and temperature – facilitating the study of trans- and supercritical phenomena. ♦ Liquid fluoroketone low dynamic viscosity and high density – resulting in very low kinematic viscosity, making high-Re testing possible at modest flow speeds. ♦ Strong fluorescence with broadband excitation – making flow tracing using common high-power lasers, such as the 3rd and 4th order harmonics of a Nd:YAG laser, possible. * Postdoctoral Associate, Mechanical and Aerospace Engineering, MAE-A 231, PO Box 116250, University of Florida, Gainesville, FL 32611, Member AIAA † Associate Professor, Mechanical and Aerospace Engineering, MAE-A 231, PO Box 116250, University of Florida, Gainesville, FL 32611, Associate Fellow AIAA T 46th AIAA Aerospace Sciences Meeting and Exhibit 7 - 10 January 2008, Reno, Nevada AIAA 2008-259 Copyright © 2008 by Jonas Gustavsson. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.