폴리비닐 부티랄에 붙힌 지르코늄 알콕시드 졸을 사용한 전기방사에서 지르코니아 나노섬유 제조와 광발광

고태경,한규석,임태균,오성규,한상환,Ko, Tae-Gyung,Han, Kyu-Suk,Rim, Tae-Kyun,Oh, Seoung-Gyu,Han, Sang-Whan 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.4

A zirconia gel/polymer hybrid nanofiber was produced in a nonwoven fabric mode by electrospinning a sol derived from hydrolysis of zirconium butoxide with a polyvinyl butyral. Results indicated that the hydroxyl groups on the vinyl alcohol units in the backbone of the polymer were involved in the hydrolysis as well as grafting the hydrolyzed zirconium butoxide. In addition, use of acetic acid as a catalyst resulted in further hydrolysis and condensation in the sol, which led to the growth of -Zr-O-Zr- networks among the polymer chains. These networks gradually transformed into a crystalline zirconia structure upon heating. The as-spun fiber was smooth but partially wrinkled on the surface. The average fiber diameter was $690{\pm}110\;nm$. The fiber exhibited a strong but broad blue photoluminescence with its maximum intensity at a wavelength of ~410 nm at room temperature. When the fiber was heat-treated at $400^{\circ}C$, the fiber diameter shrunk to $250{\pm}60\;nm$. Nanocrystals which belonged to a tetragonal zirconia phase and were ~5 nm in size appeared. A strong white photoluminescence was observed in this fiber. This suggests that oxygen or carbon defects associated with the formation of the nanocrystals play a role in generating the photoluminescence. Further heating to $800^{\circ}C$ resulted in a monoclinic phase beginning to form In the heat-treated fibers, coloring occurred but varied depending on the heating temperature. Crystallization, coloring, and phase transition to the monoclinic structure influenced the photoluminescence. At $600^{\circ}C$, the fiber appeared to be fully crystallized to a tetragonal zirconia phase.

급속 열처리된 InGaN/GaN 다중양자우물 계면요동의 Photoluminescence 연구

유진아,노영균,김문덕,서지연,오재응,김송강 한국물리학회 2010 새물리 Vol.60 No.9

The influence of an interface fluctuation in an In0.15Ga0.85N/GaN multi-quantum well (MQW) grown by using metal-organic chemical vapor deposition was investigated after rapid thermal annealing by using photoluminescence. The rapid thermal annealings were performed at temperatures between 700 and 900℃ in intervals of 50℃ for 5 minutes. After the annealing, a red-shift of the emission peak took place for all samples, and the values of Define σ implied that the degree of the localization effect was reduced by 4.2 meV compared to the value of 7 meV for the as-grown sample. These behaviors can be explained by the reduction in the In compositional fluctuation in a MQW due to annealing leading to a decrease in the quantized energies. 기상화학증착법으로 성장된 In0.15Ga0.85N/GaN 다증양자 우물구조에 대하여 급속 열처리 후 계면요동 특성변화를 photoluminescence (PL)법으로 조사하였다. 급속열처리는 700~900℃까지 50℃간격으로 5분 동안 진행하였다. 열처리 후 PL 특정결과 모든 시료들은 장파장 이동 현상을 보였으며, 또한 계면에 대한 불균일 정도를 알 수 있는 σ값은 갓 성장된 시료에 대하여 약 7meV였으나 열처리 후 4.2meV까지 감소하였다. 이런 거동은 열처리 후 계면에서의 In 요동이 감소하여 양자화 된 에너지 준위가 낮아지기 때문으로 여겨진다.

Fluorescent Liquid-Crystal Gels with Electrically Switchable Photoluminescence

Tong, X.,Zhao, Y.,An, B.-K.,Park, S. Y. WILEY-VCH Verlag 2006 Advanced Functional Materials Vol.16 No.14

<P>Fluorescent self-assembled liquid gels have been prepared for the first time through the use of a gelator showing aggregation-induced enhanced emission. The photoluminescence, arising from the fibrous aggregates of the gelator, can be repeatedly switched by an electric field. Modulating the excitation light through electric-field-induced liquid-crystal orientation offers new ways to achieve and explore electrically controllable photoluminescence.</P> <B>Graphic Abstract</B> <P>Fluorescent self-assembled liquid gels are prepared for the first time through the use of a gelator showing aggregation-induced enhanced emission. The photoluminescence, arising from the fibrous aggregates of the gelator (see figure), can be repeatedly switched by an electric field. Modulating the excitation light through electric-field- induced liquid crystal orientation offers new ways to achieve and explore electrically controllable photoluminescence. Figure width: 200 &mgr;m. <img src='wiley_img/1616301X-2006-16-14-ADFM200500868-content.gif' alt='wiley_img/1616301X-2006-16-14-ADFM200500868-content'> </P>

졸-겔법에 의한 c-축 배향성을 가진 고투과율 ZnO 박막의 제조

이영환,정주현,황규석,전영선 한국안광학회 2008 한국안광학회지 Vol.13 No.1

목적: 저온에서 열처리에 의해 소다-라임-실리카 유리 위에 강한 UV방사 나노결정 ZnO박막을 단순하고 효율적 방법으로 개선하고자 한다. 방법: 소다-라임-실리카 유리 위에 코팅되고 전열처리 및 300oC의 후열처리를 행하여 제 조된 나노 결정질 ZnO 박막의 결정 구조적, 표면 형상적 및 광학적 특성을 X-선 회절 분석, 전계방사 주사형 전자 현미경, 원자간력 현미경, ultra violet - visible - near infrared spectrophotometer 및 photoluminescence를 이용하여 분석하였다. 결과: 가시광 영역에서 높은 투과율과 자외부에서 뚜렷한 흡수밴드를 갖는 c-축으로 고배향된 ZnO 박 막을 300oC의 후열처리를 통하여 얻을 수 있었다. 비교적 뚜렷한 near band edge 발광을 보이는 photoluminescence 스펙트럼이 나타났으며, 결함에 의한 완만한 녹색 발광은 거의 관찰되지 않았다. 결론: 앞으로 본 연구는 300oC 이 하의 저온에서 저렴하고 쉽게 ZnO을 기초로한 광전기 소자에 적용될 것이다. Purpose: A simple and efficient method to prepare nanocrystalline ZnO thin film with pure strong UV emission on soda-lime-silica glass substrates by low-temperature annealing was improved. Methods: Crystal structural, surface morphological, and optical characteristics of nanocrystalline ZnO thin films deposited on soda-lime-silica glass substrates by prefiring final annealing process at 300oC were investigated by using X-ray diffraction analfield emission-scanning electron microscope, scanning probe microscope, ultraviolet-visible-near infrared specand photoluminescence. Results: Highly c-axis-oriented ZnO films were obtained by prefiring at 300oC. A high transmittance in the visible spectra range and clear absorption edge in the ultra violet range of the film was observed. The PL spectrum of ZnO thin film with a deep near band edge emission was observed while the defect-related broad green emission was nearly quenched. Conclusions: Our work will be possibly adopted to cheaply and easily fabricate ZnO-based optoelectronic devices at low temperature, below 300oC, in the future.

Photoluminescence characterization for active structural glass composite; SiO2-B2O3-ZnO doped Mn2+ glass

Y.J. Jung,T.H. Kim,Y.S. Kim,K.H. Lee,H.J. Chin,류봉기 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4

It was known that photoluminescence phenomenon was observed in Mn2+-doped SiO2-B2O3-ZnO glass after the irradiation of ultraviolet light at room temperature, and there was the shift of the spectra after heat treatment at 700 oC for crystallization. In this study, we report the effect of sintering on photoluminescence. The main emission wavelength of all samples was in a range from 520 nm to 541 nm which was different with 560 nm of ceramic produced after heat treatment for crystallization. This was measured by photoluminescence spectrometer and the change of the fluorescence was due to the alteration of crystal structure of Mn2+. The crystalline phase was analyzed as Zn5B4O11.

Photoluminescence of chemical solution-derived amorphous ZnO layers prepared by low-temperature process

어익수,황보승,김진태,황규석 한국물리학회 2010 Current Applied Physics Vol.10 No.1

Growth characteristic and optical properties of the amorphous ZnO thin films prepared on soda-lime–silica glass substrates by chemical solution process at 100 and 200 ℃ were investigated by using X-ray diffraction analysis, scanning probe microscope, ultraviolet spectrophotometer, and photoluminescence. The films exhibited an amorphous pattern even when finally heat treated at 100–200 ℃ for 60 min. The photoluminescence spectrum of amorphous ZnO films shows a strong near-band-edge emission,while the visible emission is nearly quenched.

SrAl₁₂O₁₉: Ce_x³⁺, Eu_0.01²⁺에서 시간분해 Photoluminescence을 이용한 청색발광에 관한 연구

김광철,최진수,Kim, Gwang Chul,Choi, Jin Soo 한국반도체디스플레이기술학회 2016 반도체디스플레이기술학회지 Vol.15 No.2

$SrAl_{12}O_{19}:Ce_x{^{3+}}$,$Eu_{0.01}{^{2+}}$ phosphors were synthesized through a combustion process and their optical properties were investigated using time-resolved photoluminescence. A PL spectrum showed two dominant peaks which appeared at 300 and 410 nm. It is seen that, as the $Ce^{3+}$ concentration increases, the intensity of 300 nm decreases and the intensity of 410 nm increases. This behavior has been explained by two independent energy transfer mechanism. The first energy transfer occurs from $Ce^{3+}$ ion to $Eu^{3+}$ ion. The second energy transfer takes place from $Ce^{3+}$ ion to $Ce^{3+}-O_{ME}$ complex created in the magnetoplumbite structural host materials. The blue emitting 410 nm peak has been explained by both energy transfer mechanisms.

Photoluminescence enhancement in CdS quantum dots by thermal annealing

Kim, Jae Ik,Kim, Jongmin,Lee, Junhee,Jung, Dae-Ryong,Kim, Hoechang,Choi, Hongsik,Lee, Sungjun,Byun, Sujin,Kang, Suji,Park, Byungwoo Springer 2012 Nanoscale research letters Vol.7 No.1

<P>The photoluminescence behavior of CdS quantum dots in initial growth stage was studied in connection with an annealing process. Compared to the as-synthesized CdS quantum dots (quantum efficiency ≅ 1%), the heat-treated sample showed enhanced luminescence properties (quantum efficiency ≅ 29%) with a narrow band-edge emission. The simple annealing process diminished the accumulated defect states within the nanoparticles and thereby reduced the nonradiative recombination, which was confirmed by diffraction, absorption, and time-resolved photoluminescence. Consequently, the highly luminescent and defect-free nanoparticles were obtained by a facile and straightforward process.</P>

SrAl12O19:Cex3+,Eu0.012+에서 시간분해 Photoluminescence을 이용한 청색발광에 관한 연구

김광철,최진수 한국반도체디스플레이기술학회 2016 반도체디스플레이기술학회지 Vol.15 No.2

SrAl12O19:Cex3+,Eu0.012+ phosphors were synthesized through a combustion process and their optical properties were investigated using time-resolved photoluminescence. A PL spectrum showed two dominant peaks which appeared at 300 and 410 nm. It is seen that, as the Ce3+ concentration increases, the intensity of 300 nm decreases and the intensity of 410 nm increases. This behavior has been explained by two independent energy transfer mechanism. The first energy transfer occurs from Ce3+ ion to Eu3+ ion. The second energy transfer takes place from Ce3+ ion to Ce3+-OME complex created in the magnetoplumbite structural host materials. The blue emitting 410 nm peak has been explained by both energy transfer mechanisms.

Determination of the molecular assembly of actin and actin-binding proteins using photoluminescence

Park, Byeongho,Oh, Seunghee,Jo, Seunghan,Kang, Donyoung,Lim, Juhwan,Jung, Youngmo,Lee, Hyungsuk,Jun, Seong Chan Elsevier 2018 Colloids and Surfaces B Vol.169 No.-

<P><B>Abstract</B></P> <P>Actin, the most abundant protein in cells, polymerizes into filaments that play key roles in many cellular dynamics. To understand cell dynamics and functions, it is essential to examine the cytoskeleton structure organized by actin and actin-binding proteins. Here, we pave the way for determining the molecular assembly of the actin cytoskeleton using direct photonic <I>in situ</I> analysis, providing the photoluminescence characteristics of actin as a function of filament length and bundling, without labeling. In experiments for monomeric and filamentous actin reconstituted <I>in vitro</I>, structural forms of actin are identified from the peak positions and intensities of photoluminescence. Actin monomers exhibited small intensity emission peaks at 334 nm, whereas filamentous and bundled actin showed a shifted peak at 323 nm with higher intensity. The peak shift was found to be proportional to the length of the actin filament. With probing structural change of actin in various cells <I>in vivo</I>, our study provides an efficient and precise analytical <I>in situ</I> tool to examine the cytoskeleton structure. It will be beneficial for elucidating the mechanism of various cellular functions such as cell migration, differentiation, cytokinesis and adhesion. Furthermore, our technique can be applied to detect the alterations in the cell cytoskeleton that can occur during many pathological processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Modification of actin samples with different structures using binding protein. </LI> <LI> Method for monitoring of actin structure from monomer to polymerized protein. </LI> <LI> Polymerization rate of actin under several temperatures and heat energy. </LI> <LI> Label-free detection of protein in both of <I>in vivo</I> and <I>in vitro</I> conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Actin’s structure and assembly behavior are determined by light absorption and photoluminescence characteristics under both <I>in vitro</I> and <I>in vivo</I> conditions.</P> <P>[DISPLAY OMISSION]</P>