• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.15-18
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• 1997

Intensity dependent dynamics of photoinduced absorption in $CdS_{0.4}$/$Se_{0.6}$ semiconductor doped glasses below the band gap was investigated by using time-resolved differential transmittance spectroscopy. The carriers populated through ultrafast trapping at semiconductor-glass interfaces give rise to a broad photoinduced absorption below the band gap. The decay time of transient absorption depends strongly on the excitation intensity. Based on our results, the physical mechanism for photoinduced absorption processes was suggested.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2325-2332
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• 2012

A series $[C_3Omim]$[X] of imidazolium cation-based ILs, with ether functional group on the alkyl side-chain have been synthesized and structure of the materials were confirmed by various techniques like $^1H$, $^{13}C$ NMR spectroscopy, MS-ESI, FTIR spectroscopy and EA. More specifically, the influence of changing the anion with same cation is carried out. The absorption capacity of $CO_2$ for ILs were evaluated at 30 and $50^{\circ}C$ at ambient pressure (0-1.6 bar). Ether functionalized ILs shows significantly high absorption capacity for $CO_2$. In general, the $CO_2$ absorption capacity of ILs increased with a rise in pressure and decreased when temperature was raised. The obtained results showed that absorption capacity reached about 0.9 mol $CO_2$ per mol of IL at $30^{\circ}C$. The most probable mechanism of interaction of $CO_2$ with ILs were investigated using FTIR spectroscopy, $^{13}C$ NMR spectroscopy and result shows that the absorption of $CO_2$ in ether functionalized ILs is a chemical process. The $CO_2$ absorption results and detailed study indicates the predominance of 1:1 mechanism, where the $CO_2$ reacts with one IL to form a carbamic acid. The $CO_2$ absorption capacity of ILs for different anions follows the trend: $BF_4$ < DCA < $PF_6$ < TfO < $Tf_2N$. Moreover, the as-synthesized ILs is selective, thermally stable, long life operational and can be recycled at a temperature of $70^{\circ}C$ or under vacuum and can be used repeatedly.

• 한국연소학회지
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• 제17권1호
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• pp.12-21
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• 2012

Simultaneous measurements of oxygen concentration and temperature using diode laser in the combustion environment are successfully accomplished. A single DFB type diode laser of 760 nm line centre frequency is used and the scanned-wavelength direct absorption spectroscopy method and wavelength modulation spectroscopy method are applied to measure absorption signals below 793 K temperature region. The experimental results show that oxygen concentration are measured within 1% accuracy and temperature are measured within 5% accuracy. This new method of simultaneous measurements of concentration and temperature with a single diode laser shows a great promise.

• 자연과학논문집
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• 제12권1호
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• pp.49-59
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• 2002

펌프광과 조사광이 공간적으로 떨어져 있는 경우에 포화흡수 분광신호가 지수함수적으로 감소하는 이유를 설명하였다. 수파수 안정화에 이용되는 차동포화흡수 분광신호에서 최대의 신호광에 대한 이론적으로 계산한 결과 최적 각도는 세슘원자는 $1.33^{\circ}$이고, 루비듐$87^{\circ}$은 경우 $1.08^{\circ}$이었으며, 실험결과와 일치하였다.

• 한국해양공학회지
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• 제17권6호
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• pp.77-82
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• 2003

The absorption of water into an anti-corrosive organic coating, such as alkyd and urethane resin coating, was investigated, using a quartz crystal microbalance (QCM). Anticorrosive properties of the coatings were also measured, by means of electrochemical impedance spectroscopy (EIS). The overall absorption of water in the coating is determined by the chemical nature of resin, and decreases with increasing thickness. The enhancement of anti-corrosive performance, through increase of coating thickness, was more remarkable in the case of the coating that hadlower equilibrium water absorption. The absorption kinetics curves were Fickian in nature. The EIS analysis confirmed that the resin, having lower equilibrium water absorption, shows higher anti-corrosive performan.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.211-214
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• 1990

Investigation of GaAs/AlGaAs QW carried out by using PL and Absorption spectroscopy. In order to get high resolution (0.76meV) and low noise, proper experimental system was set-up. From measurements, we have deduced the properties of GaAs/AlGaAs QW, such as the residual impurity, well thickness, crystal quality, interface abruptness and well thickness uniformity. Also we can obtain other properties such as sub-band absorption by using Absorption Spectroscopy.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.247-248
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• 2003

Tunable diode laser absorption spectroscopy (TDLAS) has been widely used in environmental monitoring of gaseous species in the past decade. TDLAS is a direct measurement technique for pollutants such as NOx without any interference from other species. Because of its superior spectral purity (～0.001 ­$cm^{-1}$), absorption linewidths with resolvable rotational structure can be studied in the mid infrared region where strong fundamental vibrational transitions of molecules appear. (omitted)

• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.441-444
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• 1991

The intramolecular proton transfers of 2-hydroxy-4,5-naphthotropone in room temperature solutions are studied using static and time-resolved absorption and emission spectroscopy. Dual normal and tautomer fluorescence is observed in ethanol solution, while only the tautomer fluorescence is observed in cyclohexane solution. The fluorescence lifetimes and quantum yields in ethanol and cyclohexane solutions indicate that in hydrocarbon solvents, rapid intersystem crossing competes with proton transfer in the first excited singlet state. Transient absorption spectra and kinetics indicate that proton transfer also undergoes in the first triplet state with a transfer time of ∼ 3 ns. No transient absorption from the tautomer ground state indicates a rapid back proton transfer in the ground state.

• Bulletin of the Korean Chemical Society
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• 제19권1호
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• pp.5-21
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• 1998

The purpose of this paper is to show that X-ray absorption spectroscopy (XANES and EXAFS) is a powerful technique for characterizing both crystalline and amorphous solids from structural (local order) and electronic point of view. The principle of this technique is briefly described by showing the main factors which must be considered for recording and fitting the experimental results. Some non-trivial examples have been selected for demonstrating that XAS spectroscopy is the only technique for bringing a definitive answer as for example: the determination of the local distortion of the $NiO_6$ octahedra in the $Li_{1-z}Ni_{1+z}O_2$ layered oxides and the evidence of the presence of copper pairs in the NASICON-type phosphate $CuZr_2 (PO_4)_3$. Are also reported some significant examples for which XAS spectroscopy is decisive with other characterization methods as (i) Raman spectroscopy for glasses (ii) Mossbauer spectroscopy for $LiNi_{1+z-t}Fe_To_2$ oxides (iii) magnetic measurements for Ce-based intermetallic compounds.

• 한국광학회지
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• 제2권4호
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• pp.209-213
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• 1991

최근들어 극초단 광학펄스를 생성하고 증폭하는 기술의 발달로 인하여 시분해 레이저 분광학에 많은 영향을 끼치게 되었다. 그 중에서도 응용성이 넓은 순간흡수분광학장치를 본 연구실에서 개발하였다. 이 기술은 고출력 레이저 펄스를 이용하여 white light continuum pulse를 생성시켜 이를 조사빔으로 이용하고, pump pulse는 원래 상태의 레이저를 이용하는 것이다. 순간흡수율 변화를 여러 파장에서 측정가능하도록 photodiode array를 이용하였으며, pump와 probe pulse의 시간차이에 의한 순간흡수율 변화를 색소의 일종인 DDI를 이용하여 측정하였다.