• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
• /
• pp.95-98
• /
• 1999

This paper describes preliminary discussions on spatial distribution of NO density, which is mostly contained in simulated NOX exhaust, between a wire-cylinder geometry discharge gaps by using Laser Induced Fluorescence(LIF) Spectroscopy. Spatial distribution of NO density will be measured with varying NO concentrations from 166 to 644[ppm] and diameters of central electrode from 6 to 10mm. Pulsed Nd:YAG laser, Optical Parametric Oscillator(OPO), and Frequency Doubler are used to excite NO molecules to their excited state.

• Journal of Mechanical Science and Technology
• /
• 제15권12호
• /
• pp.1808-1815
• /
• 2001

The characteristics of a pulsed plasma jet originating from an electrothermal capillary discharge have been investigate using laser-induced fluorescence (LIF) measurement. Previous emission measurements of a 3.1 kJ plasma jet show trial upstream of the Mach disk the temperature and electron number density are about 14,000 K and and 10$\^$17/ cm$\^$-3/, while downstream of the Mach dick tole values are about 25,000 K and 10$\^$18/ cm$\^$-3/, respectively. However, these values are barred on line-of-sight integrated measurements that may be misleading. Hence, LIF is being used to provide both spatially and temporally resolved measurements. Our recent work has been directed at using planar laser-induced fluorescence (PLIF) imaging of atomic copper in the plasma jet flow field. Copper is a good candidate for PLIF studies because it is present throughout the plasma and has electronic transitions that provide an excellent pump-detect strategy. Our PLIF results to date show that emission measurements may give a misleading picture of the flow field, as there appeals to be a large amount of relatively low temperature copper outside the barrel shock. which may lead to errors in temperature inferred from emission spectroscopy. In this paper, the copper LIF image is presented and at the moment, relative density of atomic copper, which is distributed in the upstream of the pulsed plasma jet, is discussed qualitatively.

• Nuclear Engineering and Technology
• /
• 제32권5호
• /
• pp.446-456
• /
• 2000

Laser induced photoacoustic, fluorescence, and photon correlation spectroscopies were applied to the chemical characterization of radionuclides in connection with the radiowaste treatment and disposal. Their measuring principles and systems were briefly described together with their advantages over conventional spectroscopies. Also, other applications of lasers are introduced. Laser induced photoacoustic spectra were measured for a P $r^{3+}$ solution with a very low molar absorptivity. The detection sensitivity was 4.3 $\times$10$^{-5}$ c $m^{1}$ and was 100 times better than that of a UV/VIS spectrophotometer. The Eu(III) excitation spectra($^{7}$ $F_{0}$ longrightarrow $^{5}$ $D_{0}$ transition) were measured for Eu(III)-phthalate complexes using laser fluorescence spectroscopy, showing that only two species, 1:1 and 1:2 complexes, are present in the Eu(III)-phthalic acid system. The size and size distribution for colloidal humic acids and Eu(III)-humate colloids was determined using photon correlation spectroscopy. The presence of Eu(III) enhanced the aggregation of humic acids.s.

• 한국가시화정보학회지
• /
• 제2권1호
• /
• pp.52-56
• /
• 2004

Several visualization techniques of laser diagnostics are presented for combustion phenomena, including Mie scattering for flow, Rayleigh and Raman scattering spectroscopy for major species, laser-induced fluorescence for minor species, and laser-induced incandescence for soot. These techniques have been applied to understand the various combustion phenomena more clearly, including buoyancy-dominant flow system, diffusion flam oscillation, laminar and turbulent lifted flames, flame propagation along a vortex ring, and soot zone characteristics. The usefulness of laser diagnostics on a better understanding of physical mechanism is demonstrated.

• Bulletin of the Korean Chemical Society
• /
• 제20권12호
• /
• pp.1441-1446
• /
• 1999

Laser-induced fluorescence (LIF) spectroscopy has been applied to study the supersonic jet of radicals of nitric oxide (NO) and atomic iodine produced in the flash pyrolysis of precursors n-butylnitrite (CH₃(CH₂)₃ONO) and allyl iodide (C₃$H_5$I), respectively. The systematic population analysis with spectral simulations demonstrates that the precursors are efficiently pyrolyzed and that radical beams show a substantial supersonic cooling. In addition, absence of local equilibrium was observed in the distributions of two electronic spin-orbit states ²Π$_{1/2}$ and ²Π$_{3/2}$ of NO products and can be rationalized in terms of the efficiency of collision-induced energy transfer rates.

• 한국응용과학기술학회지
• /
• 제31권2호
• /
• pp.167-175
• /
• 2014

혼탁매질에서 형광, 산란과 응집의 영향은 파장과 산란된 형광세기로 나타내는데, laser induced fluorescence(LIF) 분광학에 의한 분자특성으로 나타난다. 산란매질에서 광학적 효과는 광학적 파라미터들(${\mu}_s$, ${\mu}_a$, ${\mu}_t$)에 의해 표현되고 응집은 고-액상 분리공정과 Photodynamic therapy에서 중요하게 활용되고 있다. 따라서 입자가 서로 접근될 때 콜로이드 입자들의 상호작용을 LIF와 응집효과로 분석하였다. 우리는 레이저 광원에서 검출기까지 농도의 함수에 의해 in vitro 시료의 산란과 형광 스펙트라를 측정하였다. 산란계수 ${\mu}_s$는 산란체의 입자가 증가함에 크게 나타났다. 그리하여 Phorphyrin A는 Phorphyrin C보다 산란세기는 증가하였으나, 침투깊이 ${\delta}$는 감소하였다.

• 대한기계학회논문집B
• /
• 제20권2호
• /
• pp.710-719
• /
• 1996

Laser applied combustion diagnostic techniques-laser induced fluorescence (LIF) and coherent anti-Stokes Ramann spectroscopy (CARS)-are demonstrated. The profiles of hydroxyl radical (OH) and temperature in the counterflow burner are measured and compared with the numerical results. OH radical is excited on the Q$_1$(6) line of the $A^2$$\sum^+$$\leftarrow$$X^2{\prod}$(1, 0) band transition (281.1 nm) and LIF signal is measured at the the bands of (0, 0) and (1, 1) transition (306~326 nm). Absolute OH radical is obtained by using the laser absorption technique. The quenching effects are considered. Temperature is measured using broadband CARS system. Two dimensional OH radical profile is also obtained. The profiles of OH radical and temperature are found to agree well with those of numerical calculation.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제19권5호
• /
• pp.18-25
• /
• 2014

Traditional investigation procedures of soil and groundwater contamination are followed by soil gas sampling, soil sampling, groundwater sampling, establishment of monitoring wells, and groundwater monitoring. It often takes several weeks to obtain the analysis reports, and sometimes, it needs supplemental sampling and analysis to delineate the polluted area. Laser induced fluorescence (LIF) system is designed for the detection of free-phase petroleum pollutants, and it is suitable for on-site real-time site investigation when coupling with a direct push testing tool. Petroleum products always contain polycyclic aromatic hydrocarbon (PAH) compounds possessing fluorescence characteristics that make them detectable through LIF detection. In this study, LIF spectroscopy of 5 major fuel products was conducted to establish the databank of LIF fluorescence characteristic spectra, including gasoline, diesel, jet fuel, marine fuel and low-sulfur fuel. Multivariate statistical tools were also applied to distinguish LIF fluorescence characteristic spectra among the mixtures of selected fuel products. This study successfully demonstrated the feasibility of identifying fuel species based on LIF characteristic fluorescence spectra, also LIF seemed to be uncovered its powerful ability of tracing underground petroleum leakages.

• 한국응용과학기술학회지
• /
• 제29권1호
• /
• pp.122-128
• /
• 2012

L-arpartic acid의 산란혼탁매질에서 형광, 산란과 응집의 영향은 파장과 산란된 형광세기로 나타내는데, laser induced fluorescence(LIF) 분광학에 의한 분자특성으로 나타난다. 산란매질에서 광학적 효과는 광학적 파라미터들(${\mu}_s$, ${\mu}_a$, ${\mu}_t$)에 의해 표현되고 응집은 고-액상 분리공정에서 중요하게 활용되고 있다. 따라서 입자가 서로 접근될 때 콜로이드 입자들의 상호작용을 LIF와 응집효과로 분석하였다. 레이저 광원에서 검출기까지 농도의 함수에 의해 농도가 묽어짐에 따라 산란세기가 기하급수적으로 감소함을 알 수 있다. 이는 유지화학, 생의학 생성물, 레이저 의학, 의공학 분야적용에 LIF와 입자이동 현상은 아주 적합한 모델 연구에 큰 도움이 될 것이다.

• Bulletin of the Korean Chemical Society
• /
• 제19권10호
• /
• pp.1042-1047
• /
• 1998

The fluorescence excitation (FE) spectrum of the S1-S0 (1B2-1A1) transition of dimethyldiazirine cooled in supersonic jet expansions has been obtained. Dispersed fluorescence (DF) spectra have also been taken for some prominent features of the FE spectrum. Vibrational analyses of the FE and DF spectra with the help of an ab initio molecular orbital calculation lead to some new vibrational assignments and refined fundamental frequencies.