Achiral CdSe quantum dots exhibit optical activity in the visible region upon post-synthetic ligand exchange with d- or l-cysteine

2013 ◽  
Vol 49 (18) ◽  
pp. 1844 ◽  
Author(s):  
Urice Tohgha ◽  
Krisztina Varga ◽  
Milan Balaz
Keyword(s):  
Quantum Dots ◽  
Optical Activity ◽  
Ligand Exchange ◽  
Visible Region ◽  
Cdse Quantum Dots ◽  
Synthetic Ligand

The in situ ligand exchange linker-assisted assembly of oil-soluble CdSe quantum dots to TiO2 films

2019 ◽  
Vol 475 ◽  
pp. 813-819 ◽  
Author(s):  
Di Zhang ◽  
Pin Ma ◽  
Shuo Wang ◽  
Mingpeng Xia ◽  
Sidong Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ligand Exchange ◽  
Cdse Quantum Dots ◽  
Tio2 Films

The Effect of Quantum Confinement on Optical Properties of CdSe Quantum Dots at Room Temperature

2021 ◽  
Vol 900 ◽  
pp. 121-130
Author(s):  
Roaa Sh. Hammad ◽  
Nidhal M. Abdul-Ameer
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Dot ◽  
Absorption Coefficient ◽  
Imaginary Part ◽  
Room Temperature ◽  
Optical Constants ◽  
Visible Region ◽  
Cdse Quantum Dots ◽  
The Real

CdSe quantum dots possess a tuning energy gap which can control gap values according to the size of the quantum dots, this is made the material able to absorb the wavelengths within visible light. A simple model is provided for the absorption coefficient, optical properties, and optical constants for CdSe quantum dots from the size 10nm to 1nm with the range of visible region between (300-730) nm at room temperature. It turns out that there is an absorption threshold for each wavelength, CdSe quantum dots begin to absorb the visible spectrum of 1.4 nm at room temperature for a wavelength of 300 nm. It has been noted that; when the wavelength is increased, the absorption threshold also increases. This applies to the optical properties and optical constants, where their values start to change from the threshold at 1.4 nm. The obtained results indicate that the range of the absorption coefficient can cover the ultraviolet, visible and to the infrared region when the quantum sizes are relatively large ( the size  9 nm), while the small sizes give small ranges of it, as only the ultraviolet region (the size = 1.4 nm) or part of the visible region ( the size > 1.4 nm ). What resulted from this difference in the results of the absorption coefficient, had a significant impact on the optical properties. Although the material has high transmittance ( reach more 75%), it is considered to have low absorbance ( less than 0.01%), at the same time the reflectivity had been valued between ( 14% to 22%) according to of size dot. The optical conductivity is proportional to quantum dot size, where an increase of it depends on the increasing of quantum dot size. It was also found that the real part of the dielectric constant is much greater than the imaginary part values, this is an indication that; the numbers of polarized charges towards the electric field were much greater than the polarized charges opposite to the direction of the field. It is worth noting that the behaviour of the refractive index is similar to the real part, while the extinction index resembles that of the imaginary part.

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