Han Jung Park

Publications (2)8.95 Total impact

• Article: Effects of exothermic chemical reaction on the photoacoustic effect from particulate suspensions.

  Han Jung Park, Binbin Wu, Gerald J Diebold
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  ABSTRACT: Irradiation of chemically reactive particulate suspensions by high power, pulsed laser radiation initiates reactions at the sites of the particles so that besides the absorbed optical energy, chemical energy is liberated. In addition to the release of chemical energy, chemical reaction can result in gas production both of which result in enhancement in the amplitude of the photoacoustic effect. Here we report photoacoustic and transient grating experiments with colloidal C in mixtures of H(2)O(2) with H(2)O. The inclusion of H(2)O(2) in an aqueous C suspension changes the normally endothermic reaction of C with H(2)O into the highly exothermic reaction of C with H(2)O(2) leading to both an enhanced photoacoustic effect and an increase in light emission from the suspension. As well, laser-initiated exothermic reactions in suspensions of C with CH(3)NO(2) and particulate Hg(CNO)(2) in H(2)O are shown to result in greatly enhanced photoacoustic signal amplitudes.
  The Journal of chemical physics 03/2011; 134(12):124513. · 3.09 Impact Factor
• Article: Comparison of ultrasonic distillation to sparging of liquid mixtures.

  Hye Yun Jung, Han Jung Park, Joseph M Calo, Gerald J Diebold
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  ABSTRACT: The application of intense ultrasound to a liquid-gas interface results in the formation of an ultrasonic fountain and generates both mist and vapor from the liquid. Here, the composition of the vapor and aerosol above an ultrasonic fountain is determined as a function of irradiation time and compared with the results of sparging for five different solutions. The experimental apparatus for determining the efficiency of separation consists of a glass vessel containing a piezoelectric transducer driven at either 1.65 or 2.40 MHz. Dry nitrogen is passed over the ultrasonic fountain to remove the vapor and aerosol. The composition of the liquid solutions are recorded as a function of irradiation time using gas chromatography, refractive index measurement, nuclear magnetic resonance, or spectrophotometry. Data are presented for ethanol-water and ethyl acetate-ethanol solutions, cobalt chloride in water, colloidal silica, and colloidal gold. The experiments show that ultrasonic distillation produces separations that are somewhat less complete than what is obtained using sparging.
  Analytical Chemistry 11/2010; 82(24):10090-4. · 5.86 Impact Factor