# 2-D IMAGES OF DENSITY DISTRIBUTIONS OF $O_{2}$ IN SPECIFIC v,J QUANTUM STATES OBTAINED VIA PREDISSOCIATIVE LASER INDUCED FLUORESCENCE

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 Title: 2-D IMAGES OF DENSITY DISTRIBUTIONS OF $O_{2}$ IN SPECIFIC v,J QUANTUM STATES OBTAINED VIA PREDISSOCIATIVE LASER INDUCED FLUORESCENCE Creators: Kim, Gyung-Soo; Hitchcock, Lynne M.; Rothe, Erhard W.; Reck, Gene P. Issue Date: 1990 Publisher: Ohio State University Abstract: We report data from a new method, originally described by P. $Andresen^{1}$ et al., that produces instantaneous 2-D images of state-specific molecular concentrations, and is ideal for observation of gaseous, turbulent reacting systems. This excimer-laser based approach yields state-specific 2-D distribution for each of a number of constituents and it should also yield temperature fields. The method applies within a wide temperature and pressure range because it is based upon a novel variant of laser induced fluorescence (LIF) which eliminates the collisional quenching that limits the quantitative use of normal LIF to pressures $<=10$ torr. This limitation is overcome by exciting molecules that are in a selected ground quantum state to predissociating states which are so short-lived (1-10ps) that there is no time for quenching collisions. The imaging technique uses a ribbon of narrow-band laser-light that passes through a medium. The laser's wavelength is tuned, in the range 193-193.8nm, to a desired transition. Fluorescence light is recorded by an intensified CCD camera that is pointed at $90^{\circ}$ to the path of the light-ribbon. Our narrow-band laser is bright enough that a single pulse yields a 2-D image. The laser is also a flashbulb'' that determines the time scale. Our laser pulse lasts =15ns which is essentially stop action'' for turbulent phenomena. If we assume a molecular velocity of one km/s, a molecule would move only =15ns during the pulse. As an example, we show 2-D images of vibrationally excited $O_{2}$ in several types of open flames Description: $^{1}$ P. Andresen, A. Bath, W. Groger, H. W. Liilf, G. Meijer, and J.J. ter Meulen, Appl. Opt. 27, 365 (1988). Author Institution: Department of Chemical Engineering, Wayne State University; Department of Chemistry, Wayne State University URI: http://hdl.handle.net/1811/18332 Other Identifiers: 1990-TG-6