CAJ | 학술논문

影响量子点荧光特性除了量子点尺寸因素外，其溶液浓度也会对其荧光特性起很重要的作用。但到目前，还未见到有关量子点 CdSe／ZnS 在溶液中浓度对其荧光影响的详细报道。为了掌握影响量子点CdSe／ZnS荧光特性的因素及其物理机制，利用紫外-可见吸收光谱仪和荧光光谱仪测量了尺寸为4 nm的量子点CdSe／ZnS在氯仿中不同浓度下的吸收光谱和荧光光谱，并侧重研究了量子点CdSe／ZnS的浓度对其发光特性的影响并分析了其物理机制。结果表明量子点对光谱的吸收随其浓度的增加而增大，但其发光却具有一个最佳浓度2μmol·L－1。当量子点的浓度＞2μmol·L－1时，量子点的荧光强度随着量子点浓度的增加而降低，而当量子点的浓度＜2μmol·L－1时，量子点的发光强度则随其浓度的降低而降低。其原因主要有两个：（1）荧光猝灭效应；（2）荧光发射与光吸收的竞争效应。当量子点的浓度＞2μmol·L－1时，由于量子点之间相距太近（仅为94 nm）而引起了荧光猝灭效应，且其荧光猝灭效应随量子点间距的减小而增大，且因为吸收过大，导致受激的量子点并未增加，因此，其荧光随浓度的增加而降低。而当量子点的浓度＜2μmol·L－1时，因为量子点之间的距离足够大，不再引起荧光猝灭效应，其荧光强度取决于单位体积内的量子点的个数，单位体积内量子点的个数越多，其发光强度越强。因此其发光强度随量子点溶液的浓度降低而降低。
영향양자점형광특성제료양자점척촌인소외，기용액농도야회대기형광특성기흔중요적작용。단도목전，환미견도유관양자점 CdSe／ZnS 재용액중농도대기형광영향적상세보도。위료장악영향양자점CdSe／ZnS형광특성적인소급기물리궤제，이용자외-가견흡수광보의화형광광보의측량료척촌위4 nm적양자점CdSe／ZnS재록방중불동농도하적흡수광보화형광광보，병측중연구료양자점CdSe／ZnS적농도대기발광특성적영향병분석료기물리궤제。결과표명양자점대광보적흡수수기농도적증가이증대，단기발광각구유일개최가농도2μmol·L－1。당양자점적농도＞2μmol·L－1시，양자점적형광강도수착양자점농도적증가이강저，이당양자점적농도＜2μmol·L－1시，양자점적발광강도칙수기농도적강저이강저。기원인주요유량개：（1）형광졸멸효응；（2）형광발사여광흡수적경쟁효응。당양자점적농도＞2μmol·L－1시，유우양자점지간상거태근（부위94 nm）이인기료형광졸멸효응，차기형광졸멸효응수양자점간거적감소이증대，차인위흡수과대，도치수격적양자점병미증가，인차，기형광수농도적증가이강저。이당양자점적농도＜2μmol·L－1시，인위양자점지간적거리족구대，불재인기형광졸멸효응，기형광강도취결우단위체적내적양자점적개수，단위체적내양자점적개수월다，기발광강도월강。인차기발광강도수양자점용액적농도강저이강저。
The authors measured the absorption and the fluorescence spectra of the quantum dots CdSe/ZnS with 4 nm in size at different concentration with the use of the UV-Vis absorption spectroscopy and fluorescence spectrometer.The effect of quantum dots CdSe/ZnS’s concentration on its fluorescence was especially studied and its physical mechanism was analyzed.It was ob-served that the optimal concentration of the quantum dots CdSe/ZnS for fluorescence is 2μmol·L-1 .When the quantum dot’s concentration is over 2μmol·L-1 ,the fluorescence is decreased with the increase in the concentration.While the quantum dot’ s concentration is less than 2μmol·L-1 ,the fluorescence is decreased with the decrease in the concentration.There are two main reasons:1)fluorescence quenching and 2)the competition between absorption and fluorescence.When the quantum dot’s concentration is over 2μmol·L-1 ,the distance between quantum dots is so close that the fluorescence quenching is induced. The closer the distance between quantum dots is,the more serious the fluorescence quenching is induced.Also,in this case,the absorption is so large that some of the quantum dots can not be excited because the incident light can not pass through the whole sample.As a result,the fluorescence is decreased with the increase in the quantum dot’s concentration.As the quantum dot’s concentration is below 2μmol·L-1 ,the distance between quantum dots is far enough that no more fluorescence quenching is in-duced.In this case,the fluorescence is determined by the particle number per unit volume.More particle number per unit vol-ume produces more fluorescence.Therefore,the fluorescence is decreased with the decrease in the quantum dot’s concentration.