scholarly journals Excitation wavelength independent visible color emission of carbon dots

Nanoscale ◽  
2017 ◽  
Vol 9 (5) ◽  
pp. 1909-1915 ◽  
Author(s):  
Hua Wang ◽  
Chun Sun ◽  
Xingru Chen ◽  
Yu Zhang ◽  
Vicki L. Colvin ◽  
...  
2021 ◽  
Vol 9 (10) ◽  
pp. 3901-3908
Author(s):  
Fanyong Yan ◽  
Hao Zhang ◽  
Jinxia Xu ◽  
Yawei Wu ◽  
Yueyan Zang ◽  
...  

MRS Advances ◽  
2017 ◽  
Vol 2 (51) ◽  
pp. 2927-2934 ◽  
Author(s):  
Zhoufeng Jiang ◽  
Marta J. Krysmann ◽  
Antonios Kelarakis ◽  
Petr Koutnik ◽  
Pavel Anzenbacher ◽  
...  

ABSTRACTThe carbon dots were investigated to reveal their light-emitting mechanism. The fluorescence spectra of carbon dots show typically two different types of photoluminescence: the excitation-independent component in the short wavelength, and the excitation-dependent component in the longer wavelength. The UV-Vis spectrum of carbon dots shows the absorption maximum of 340 nm which should be accredited to the n-π* transition of the carbonyl group in carbon dots. Absolute quantum yields of carbon dots dispersed in Polyvinyl alcohol is around 15% when the excitation wavelength is less than 425 nm, but decreases continuously when the excitation wavelength increases. The decay lifetimes of the carbon dots also show an abrupt change at excitation wavelength 425 nm. Time resolved photoluminescence was implemented from 31K to 291K to study the photoluminescence decay dynamics of carbon dots, resulting in the continuously decreasing of the lifetime as the temperature increases.


In this, a series of iso-structural Y2O2S (RE3+ = Dy3+ , Eu3+ and Tb3+) phosphors were synthesized by high temperature solid state reaction method. All the phosphors exhibit strong line and broad excitation in the near ultraviolet (n-UV) region. Bright color emission in blue, green and red color region of electromagnetic hue cycle was noticed. The concentration of activator doped was optimized from the photoluminescence (PL) study. The quenching in luminescence intensity after particular concentration of dopant is discussed here. Y2O2S phosphor doped with Dy3+displays useful blue and yellow emission bands at 487nm and 574nm, when stimulated by 388nm excitation wavelength. Y2O2S:Eu3+ phosphor displays an orange and red emission at 594nm and 620nm, when stimulated at 396 nm. Whereas, Y2O2S:Tb3+ phosphor displays weak blue radiation in the range 485nm and strong green radiation at 545nm, when stimulated at 305 nm. The excitation spectra used for the Y2O2S:RE3+ (RE3+ = Dy3+ , Eu3+ and Tb3+) phosphor is in the near ultraviolet (n-UV) region spanning from 300 nm to 400 nm, which is a peculiarity of near ultraviolet stimulated LED. The outcome of the RE3+ (RE3+= Dy3+ , Eu3+and Tb3+) absorption on the luminescence properties of Y2O2S:RE3+ phosphors was also studied.


Lab on a Chip ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 3974-3978 ◽  
Author(s):  
Meng Shao ◽  
Qin Yu ◽  
Nan Jing ◽  
Yu Cheng ◽  
Dong Wang ◽  
...  

Continuous synthesis of carbon dots with full-spectrum fluorescence and the mechanism of their multiple color emission and applications.


Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1171 ◽  
Author(s):  
Dan Zhao ◽  
Wenting Ma ◽  
Rong Wang ◽  
Xinzhou Yang ◽  
Jun Li ◽  
...  

Fluorescence/temperature-sensitive hydrogels, thanks to their properties in fluorescence and temperature sensitivity, have shown a promising outlook in the fields of drug delivery, cell imaging, etc., and thus become the focus of present research. This paper reports the preparation of green-fluorescence/temperature-sensitive hydrogels through one-step radical polymerization with green fluorescence-emissioned carbon dots as fluorescence probes and N-isopropylacrylamide as a monomer. UV-vis spectra, fluorescence spectra, and fluorescence microscope imaging have been used to characterize the prepared hydrogel, and to study their optical and temperature-sensitive properties. It was discovered that the emission of prepared hydrogel is excitation wavelength-dependent, pH responding, and excellent temperature-sensitive, as well as having good biocompatibility. The prepared hydrogel can also be applied as fluorescence ink in the fields of anti-counterfeit identification and appraisal.


2020 ◽  
Vol 8 ◽  
Author(s):  
Yizhou Yang ◽  
Xuemei Chen ◽  
Yangyang Wang ◽  
Miao Wu ◽  
Yinan Ma ◽  
...  

In recent years, carbon dots (CDs) are promising fluorescence probes for ions detection. In this paper, the CDs which are with an average diameter of 5.5 nm were synthesized through a simple one-step hydrothermal carbonization of ethylene diamine tetraacetic acid (EDTA) salt. The CDs have strong yellow photoluminescence (PL) with a maximum emission intensity at 550 nm under an excitation wavelength of 450 nm. As the electron transfer will occur between Cr (VI) and the CDs, yellow fluorescence was quenched after adding the Cr (VI) ions. The CDs probe allows the detection of Cr (VI) ions over a concentration range from 0 to 0.1 M (R2 = 0.987) and the lower detection limit is 10−5 M. Simultaneously, the CDs show highly selectivity and stability toward the detection of Cr (VI) ions.


2020 ◽  
Vol 7 (7) ◽  
pp. 200482
Author(s):  
Xiaoxue Lei ◽  
Yiying Fu ◽  
Yuan Wu ◽  
Lu Chen ◽  
Jiangong Liang

In this study, a novel ratiometric fluorescent nanoprobe for pH monitoring has been developed by synthesizing red fluorescent Ag 2 S quantum dots (Ag 2 S QDs) and green fluorescent carbon dots (CDs) nanohybrids (Ag 2 S CDs) in one pot using CDs as templates. The nanoprobe exhibits dual-emission peaks at 500 and 670 nm under a single-excitation wavelength of 450 nm. The red fluorescence can be selectively quenched by increasing pH, while the green fluorescence is an internal reference. Therefore, the change of the relative fluorescence intensity (I 500 /I 670 ) in the ratiometric Ag 2 S CDs probes can be used for pH sensing. The results revealed that I 500 /I 670 of Ag 2 S CDs probes was linearly related to pH variation between pH 5.4 and 6.8. Meanwhile, the Ag 2 S CDs probes possessed a good reversibility along with pH changing between 5.0 and 7.0 without any interruption from common metal ions, proteins and other interferences.


RSC Advances ◽  
2017 ◽  
Vol 7 (69) ◽  
pp. 43839-43844 ◽  
Author(s):  
Yefei Tian ◽  
Zhipeng Ran ◽  
Wuli Yang

A novel composite nanoparticle of silica/carbon dots showing tunable fluorescence from green to yellow without excitation wavelength dependence is fabricated.


2014 ◽  
Vol 26 (10) ◽  
pp. 3104-3112 ◽  
Author(s):  
Hui Nie ◽  
Minjie Li ◽  
Quanshun Li ◽  
Shaojun Liang ◽  
Yingying Tan ◽  
...  

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