• 한국세라믹학회지
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• 제34권4호
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• pp.429-435
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• 1997

The third order nonlinear optical susceptibilities, {{{{ chi }}(3), of the CuCl doped alumino-borosilicate glasses were measured by the two beam configuration DFWM method and the absorption saturation method, and the measured {{{{ chi }}(3) values were about 10-8 esu in both methods. The response time was estimated to be about 105ps from the time decay curve of the luminescence spectra obtained by time-correlated single-photon counting (TCSPC) method.

• 천문학회지
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• 제27권1호
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• pp.45-53
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• 1994

We present the calculation of X -ray spectra produced through Compton scattering of soft X-rays by hot electrons in the spherical shell geometry, using fully relativistic Monte Carlo simulation. With this model, we show that the power-law component, which has been observed in the low luminosity state of low-mass X-ray binaries (LMXBs), is explained physically. From a spectral. analysis, we find that spectral hardness is mainly due to the relative contribution of scattered component. In addition, we see that Wi en spectral features appear when the plasma is optically thick, especially in the high energy range, $E{\gtrsim}100keV$. We suggest that after a number of scattering the escape probability approaches an asymptotic form depending on the geometry of the scattering medium rather than on the initial photon spectrum.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.68-69
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• 2007

We have prepared p-type ZnO:Al films in pure oxygen ambient on n-type Si (100) and homo buffer layers by RF magnetron sputtering system. Hall effect measurement shows that the film annealed at $600^{\circ}C$ possesses p-type conductivity and the film annealed $800^{\circ}C$ does not. PL spectra show different properties of p- and n-type ZnO film. The corresponding peaks of PL spectra of p- and n-type show at about same positions. The intensities of high photon energy of n-type film on buffer shows decreasing tendency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.225-225
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• 2013

Nanostructured noble metals have been attractive for their unusual optical properties and are widely utilized for various purposes. The optical properties mainly originating from collective electron oscillation can assist direct energy conversion via surface plasmon resonances. Here, we investigated the effect of surface plasmons of silver nanowires on the generation of hot electrons. It is reported that the surface plasmons of silver nanowires exhibit longitudinal and transverse modes, depending on the aspect ratio of the nanowires. In order to measure the hot electron flow through the metallic nanowires, chemically modified Au/TiO2 Schottky diodes were employed as the electric contact. The silver nanowires were deposited on a Au metal layer via the spray method to control uniformity and the amount of silver nanowire deposited. We measured the hot electron flow generated by photon absorption on the silver nanowires deposited on the Au/TiO2 Schottky diodes. The incident photon-to-current efficiency was measured a function of the photon energy, revealing two polarization modes of siliver nanowires: transverse and longitudinal modes. UV-Vis spectra exhibited two polarization modes, which are also consistent with the photocurrent measurements. Good correlation between the IPCE and UV-vis measurements suggests that hot electron measurement on nanowires on nanodiodes is a useful way to reveal the intrinsic properties of surface plasmons of nanowires.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1119-1125
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• 2003

Coherent multidimensional vibrational spectroscopy is a new technique for establishing correlations between features in vibrational spectra that are caused by intra- and intermolecular interactions. These interactions cause cross-peaks between vibrational transitions that reflect the coupling. In this paper, we use Doubly Vibrationally Enhanced Infrared Spectroscopy (DOVE-IR) and DOVE-Raman processes to obtain coherent two dimensional vibrational spectra. The spectra are fitted to obtain the dephasing rates and third order susceptibilities $(χ^{(3)})$ for the nonlinear processes. We show that the DOVE $χ^{(3)}$ values are directly related to the molar absorptivities and Raman $χ^{(3)}$. We then use these relationships to obtain estimates for the $χ^{(3)}$ of the stimulated photon echo and $χ^{(5)}$ of the six wave mixing spectroscopies, respectively. We also predict the ratio of the cascaded four wave mixing signal to the six wave mixing signal.

• 한국의학물리학회지:의학물리
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• 제17권4호
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• pp.224-231
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• 2006

본 연구에서는 MCNPX 코드를 사용하여 6 MeV 전자선의 에너지분포를 계산하였다. 이를 위하여 선형가속기(ML6M; Mitsubishi, Japan)의 헤드를 모델화하였다. 전자선의 초기에너지 분포는 가우시안으로 가정하였으며, 이 때 평균에너지는 측정과 계산으로 구한 $R_{50}$과 공기중 선량프로 파일을 평가하여 결정하였다. 결정된 빔 변수를 적용하여 선형가속기 헤드속 주요 위치에서의 전자선 에너지분포를 계산하였다. 어플리케이터 출구에서의 광자에 대한 에너지분포를 이용하여 깊이선량률에서 오염광자의 영향을 분석하였다.

• Current Applied Physics
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• 제18권11호
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• pp.1225-1229
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• 2018

In this paper, we investigated the electronic structures and defect states of $SrLaMgTaO_6$ (SLMTO) double perovskite structures by using resonant inelastic x-ray scattering. Recently, $Eu^{3+}$ doped SLMTO red phosphors have been vigorously investigated due to their higher red emission efficiency compared to commercial white light emitting diodes (W-LED). However, a comprehensive understanding on the electronic structures and defect states of host SLMTO compounds, which are specifically related to the W-LED and photoluminescence (PL), is far from complete. Here, we found that the PL spectra of SLMTO powder compounds sintered at a higher temperature, $1400^{\circ}C$, were weaker in the blue emission regions (at around 400 nm) and became enhanced in near infrared (NIR) regions compared to those sintered at $1200^{\circ}C$. To elucidate the difference of the PL spectra, we performed resonant inelastic x-ray spectroscopy (RIXS) at Ta L-edge. Our RIXS result implies that the microscopic origin of different PL spectra is not relevant to the Ta-related defects and oxygen vacancies.

• 한국안광학회지
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• 제6권2호
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• pp.71-75
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• 2001

본 논문에서는 열자극발광 스팩트럼을 온도, 파장, 발광강도의 3차원으로 측정할 수 있는 장치를 소개하고, 고감도 TLD인 $CaSO_4$ : Dy, P의 열자극발광을 이 장치를 이용하여 측정하였다. 측정시스템은 분광장치(spectrometer), 열자극을 위한 온도조절부, 광검출기(photon detector) 그리고 전체 시스템을 제어하고 측정 데이터를 기록 및 디스플레이하기 위한 컴퓨터로 구성되어 있다. 온도조절은 피드백(feedback)을 방식을 이용하였고, 피드백을 위한 온도는 디지털멀티미터로 측정하고 GPIB를 통하여 제어용 컴퓨터에 보내지고 컴퓨터는 전원공급기(power supply)를 제어하게 된다. 분광장치는 SPEX CD-2A를 통하여 컴퓨터에 의해 제어되고 광검출은 광증배관(photomultiplier tube)을 이용하여 측정하고 A/D 변환기를 통하여 컴퓨터에 보내져 저장되게 된다. 고강도 TL 물질인 $CaSO_4$ : Dy, P의 열자극발광을 위 장치를 이용하여 측정하였다. 측정영역은 온도 $30{\sim}300^{\circ}C$ 그리고 파장 300~800 nm였다. $CaSO_4$ : Dy. P 물질은 한국원자력연구소에서 Yamashita법으로 누적 방사선량 측정용으로 개발된 물질이다. 측정결과 온도 약 $250^{\circ}C$, 파장 약 476 nm 그리고 572 nm에서 2개의 주(main) 피크(peak)가 관측되었으며, 온도 $205^{\circ}C$, 파장 658 nm 그리고 749 nm에서 매우 약한 발광 피크가 관측되었다.

• 한국의학물리학회지:의학물리
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• 제8권2호
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• pp.35-43
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• 1997

광자선의 흡수계수교정과 차등 투과력이 관련된 연구에서 X선의 스펙트럼은 중요한 관심사이다. 본 연구에서는 전산화단층영상장치의 80, 120 kVp X선의 실험적 투과선량으로부터 수치해석을 통해 에너지스펙트럼을 구하였다. 투과선량은 직경 30cm, 두께 5mm 내지 92.3 mm의 알루미늄 파이프필터의 중앙에 반도체검출기를 설치하고 10mm 슬릿빔의 투과선량을 측정하였다. 스펙트럼재구성은 텅스텐타켓의 특성 X선을 포함한 반복적 수치 해석을 통해 에너지 구간별 스펙트럼을 구하였으며 에너지구간은 2keV로 하였다. 재구성한 에너지분포를 이용하여 계산된 투과선량과 측정투과선량의 비교는 두 광자에너지에서 모두 좋은 일치를 보였다. 에너지구간별 분할조사선량의 반복적 계산에 근거를 둔 수치해석은 흡수체의 감쇄된 선속으로부터 X선의 에너지스펙트럼을 매우 유용하게 결정할 수 있음을 보여주었다.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.73-76
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• 2005

To widen the band gap of ZnO, we have investigated $Zn_{1-x}Mg_xO(ZMO)$ thin films prepared by pulsed laser deposition on c-plane sapphire substrates at $500^{\circ}C$. From X-ray diffraction patterns, ZMO films show only the (0002) and (0004) diffraction peaks. It means that the flints have the wurtzite structure. Segregation of ZnO and MgO phases is found in the films with x=0.59. All the samples are highly transparent in the visible region and have a sharp absorption edge in the UV region. The shift of absorption edge to higher energy is observed in the films with higher Mg composition. The excitonic nature of the films is clearly appeared in the spectra for all alloy compositions. The optical band-gap ($E_g$) of ZMO films is obtained from the ${\alpha}^2$ vs Photon energy plot assuming ${\alpha}^2\;\propto$ (hv - $E_g$), where u is the absorption coefficient and hv is the photon energy. The value of $E_g$ increases up to 3.72 eV for the films with x=0.35. It is important to adjust Mg composition control for controlling the band-gap of ZMO films.