| 查看: 1154 | 回复: 10 | ||
| 【奖励】 本帖被评价3次，作者bern增加金币 2.5 个 | ||
| 当前主题已经存档。 | ||
| 当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖 | ||
[资源]
【资源】Nature 新出文章----Non blinking Quantum Dot
|
||
|
很牛啊，不闪烁的量子点，怪不得能发nature呢。 刚刚出来的，5.10号上的网。大家可以看看，如今QD能发nature的文章不多了。 http://pubs.acs.org/cen/news/87/i20/8720news4.html Quantum Dots That Don't Blink Core structure suppresses blinking and leads to unusual spectral behavior Celia Henry Arnaud A team of scientists has synthesized semiconductor nanocrystals, or quantum dots, that are "nonblinking," in that they emit light steadily. Such behavior has long been a goal of scientists working with quantum dots and should improve the usefulness of the nanocrystals for biological labeling applications by increasing the number of photons the particles emit. Ted Palwicki View Enlarged Image NO BLINKING Quantum dots with a gradient core emit continuously and at multiple wavelengths.Blinking is a hallmark of fluorescent single molecules and nanometer-scale crystals; it occurs because the luminescence intermittently turns off even with continuous excitation. Excited quantum dots get rid of their extra energy through radiative processes—by emitting light—or nonradiative processes. "When the dot blinks off, nonradiative processes are winning," says team leader Todd D. Krauss, associate professor of chemistry at the University of Rochester. In quantum dots, this blinking is thought to be the result of extra charges that enhance nonradiative decay. Krauss's team eliminates the blinking by making quantum dots whose compositions gradually change from the center to the shell (Nature, DOI: 10.1038/nature08072). They layer ZnSe on top of a CdSe core, anneal the layers, and deposit additional ZnSe around it. The process generates a ternary core with a radial composition gradient that smooths the particle's potential energy function and makes nonradiative processes less efficient. However, the nonblinking comes with unusual spectral behavior. Quantum dots usually have a single, sharp emission peak. The new quantum dots, in contrast, have multiple peaks in their emission spectra. Multiple peaks might mean emission spectra of different quantum dots will overlap, which could complicate their use as biological sensors. The extra peaks come from part of the quantum dots' excitation energy being emitted as photons at longer wavelengths. In addition, the time the unblinking quantum dots stay in their excited state before emitting a photon is much shorter than that of traditional CdSe nanocrystals. Krauss and coworkers, including Alexander L. Efros of the Naval Research Laboratory, posit that both the suppressed blinking and the unusual spectral characteristics can be explained by the lower efficiency nonradiative processes caused by the composition gradient. "Nonradiative processes become efficient only when you have very sharply defined potential barriers," Krauss says, and the gradient rounds off the corners of the potential energy function. Krauss plans to test their model of quantum dot behavior by varying the materials and sizes of nonblinking quantum dots. Jennifer Hollingsworth, a chemist at Los Alamos National Laboratory who also is developing nonblinking quantum dots, comments that the work by Krauss and coworkers is "certainly an interesting addition" to earlier studies by two groups, including hers, that reported having significantly suppressed but not completely eliminated blinking in semiconductor nanocrystals. "It will be important to see whether they will be able to extend this approach to other systems and whether this thin-shell motif will hold up to processing." |
回复此楼» 猜你喜欢
化工学院（学院正式调剂群+联系方式）
已经有0人回复
-
化工学院（学院官方群）-院士团队招生-学生自由度高-培养模式成熟高效
已经有0人回复
-
金属材料论文润色/翻译怎么收费?
已经有154人回复
-
黑龙江大学分析化学招调剂
已经有0人回复
-
武汉高校国家级人才团队招收材料，化学，纺织等专业硕士调剂生
已经有26人回复
-
纺大化工学院（官方群）-院士团队招生-学生自由度高发展好-培养模式成熟
已经有0人回复
-
温州大学化材学院王娟课题组招生
已经有5人回复
-
学院官方群-院士团队招生-学生自由度高-培养模式成熟已有10余名学生赴985海外深造
已经有0人回复
-
武汉纺织大学化工学院官方群-院士团队招生-学生自由度高-10余名学生赴985海外深造
已经有0人回复
-
南昌航空大学蒋华麟教授课题组招收化学、环境、碳达峰碳中和及相关专业硕士信息
已经有0人回复
-
湖北师范大学复试调剂
已经有0人回复
8楼2009-08-21 10:08:44
|
本帖内容被屏蔽 |
3楼2009-05-16 03:27:43
6楼2009-05-17 17:16:56
9楼2009-08-21 22:56:01
