• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1081-1090
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• 2003

Two different electronically resonant two-dimensional spectroscopies are described. The first, two-color photon echo peak shift spectroscopy, is sensitive to correlations in transition frequency between the initial and probed (final) states. It provides new insight into the mechanism of ultrafast solvation and should prove useful for characterizing dynamics in inhomogeneous systems in general. The second technique, fifth order threepulse scattering, contains two coherence periods whose durations are controlled. The entire two-dimensional surface was recorded for a dye molecule in dilute solution and a photosynthetic light-harvesting complex. The data provide insight into the short-time dynamics of solvation and exciton relaxation, respectively.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.277-280
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• 2002

Mass-analyzed threshold ionization (MATI) spectra of 2-hydroxypyridines existing as lactims (2-pyridinol) in a molecular beam are obtained via (1+1') two-photon process to give accurate ionization energies of 8.9344${\pm}$0.0005 and 8.9284${\pm}$0.0005 eV for 2-pyridinol (2Py-OH) and its deuterated analogue (2Py-OD), respectively. Resonantly-enhanced two-photon ionization spectra of these compounds are also presented to give vibrational structures of their $S_1$ states. Vibrational frequencies of 2Py-OH and 2Py-OD in ionic ground states are accurately determined from MATI spectra taken via various $S_1$ intermediate states, and associated vibrational modes are assigned with the aid of ab initio calculations.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 광학 및 양자전자학 워크샵
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• pp.15-22
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• 1991

The general aspects of Laser Resonance Ionization Spectroscopy (RIS) and its application are investigated. Combination of laser selective photoionization and mass spectrometer as apromising spectroscopic as well as an analytical tool is mainly considered. The application of RIS includes mercury (Hg) atomic spectroscopy, trace analysis of lead (Pb) and resonance enhanced two photon ionization spectroscopy of Cis-hexatriene.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.189-194
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• 2002

Two-photon resonant third photon ionization of atomic bromine $(4p^5\;^2P_{3/2}\;and\;^2P_{1/2})$ has been studied using a photoelectron imaging spectroscopy in the wavelength region 250 - 278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of $Br^+(^3P_2,\;^3P_{0.1}\;and^1D_2)$ with $4p^4$ configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of $Br^+(^3P_2)$ and $Br^+(^3P_{0.1})$ ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive $A_2$ anisotropy coefficient of 1.0-2.0 and negligible $A_4$ in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption.

• 대한화학회지
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• 제36권6호
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• pp.832-839
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• 1992

Time-of-Flight(TOF) 질량분석기가 설치된 분광분석장치를 이용하여 레이저 공명이온화 분광법으로 극미량의 납을 정량하였다. 납에 대한 극미량 분석을 위해 단색 2광자 공명이온화, 2색 2광자 공명이온화 및 3색 3광자 공명 이온화의 세 가지 광이온화 경로가 시도되었다. 이 때, 첫번째 들뜬 준위는 바닥준위로부터 283.3 nm의 파장에 해당하는 6p7s($^3P_1$)준위를 공통적으로 사용하였다. 이들 이온화경로를 통해 여러가지 농도의 납 표준용액을 사용하여 0.1 ${\mu}g$에서 1pg의 영역에 해당하는 검정곡선을 얻었다. 검정곡선으로부터 얻은 본 분석법의 검출한계는 2색 2광자 공명이온화 및 3색 3광자 공명이온화의 경우 각각 20 및 10pg 이었다. 또한 각각의 이온화 경로에 따른 이온화 효율도 함께 비교 검토하였다.

• 광학과기술
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• 제8권4호
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• pp.26-29
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• 2004

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.815-820
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• 2014

We applied the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 2,4-difluorophenol. As supported by our theoretical calculations, only the cis form of 2,4-difluorophenol involves in the two-photon photoexcitation and pulsed field ionization processes. The band origin of the $S_1{\leftarrow}S_0$ electronic transition of cis-2,4-difluorophenol appears at 35 647 ${\pm}2cm^{-1}$ and the adiabatic ionization energy is determined to be 70 $030{\pm}5cm^{-1}$, respectively. Most of the observed active vibrations in the electronically excited $S_1$ and cationic ground $D_0$ states mainly involve in-plane ring deformation vibrations. Comparing these data of cis-2,4-difluorophenol with those of phenol, cis-2-fluorophenol, and 4-fluorophenol, we found that there is an additivity rule associated with the energy shift resulting from the additional fluorine substitution.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2004년도 제26회 학술발표회 초록집
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• pp.58-58
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• 2004

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.9-10
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• 2007

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