Strong main-chain length-dependence for the β-phase formation of oligofluorenes

2015 ◽  
Vol 6 (28) ◽  
pp. 5103-5109 ◽  
Author(s):  
Tomohiro Shiraki ◽  
Shoichiro Shindome ◽  
Fumiyuki Toshimitsu ◽  
Tsuyohiko Fujigaya ◽  
Naotoshi Nakashima

Wide range chain length-oligofluorenes (9–27 mers) have been synthesized and their optical properties are examined. Interestingly, clear chain length dependence appeared in the absorption and fluorescence functions due to β-phase formation that is a characteristic structure of fluorene materials.

2018 ◽  
Vol 9 (17) ◽  
pp. 2295-2301 ◽  
Author(s):  
Yin Zhao ◽  
Hailing Chen ◽  
Lu Yin ◽  
Xiaoxiao Cheng ◽  
Wei Zhang ◽  
...  

An “odd–even” effect for the chiral β-phase of polydialkylfluorene/limonene aggregates was first observed, depending on the odd–even alkyl side chain length.


1971 ◽  
Vol 13 (9) ◽  
pp. 2262-2271 ◽  
Author(s):  
V.N. Tsvetkov ◽  
L.N. Andreyeva ◽  
S.Ya. Magarik ◽  
P.N. Lavrenko ◽  
G.A. Fomin

Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).


2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.


2020 ◽  
Vol 25 (46) ◽  
pp. 4848-4860 ◽  
Author(s):  
Anisha Anand ◽  
Gopinathan Manavalan ◽  
Ranju Prasad Mandal ◽  
Huan-Tsung Chang ◽  
Yi-Ru Chiou ◽  
...  

: The prevention and treatment of various infections caused by microbes through antibiotics are becoming less effective due to antimicrobial resistance. Researches are focused on antimicrobial nanomaterials to inhibit bacterial growth and destroy the cells, to replace conventional antibiotics. Recently, carbon dots (C-Dots) become attractive candidates for a wide range of applications, including the detection and treatment of pathogens. In addition to low toxicity, ease of synthesis and functionalization, and high biocompatibility, C-Dots show excellent optical properties such as multi-emission, high brightness, and photostability. C-Dots have shown great potential in various fields, such as biosensing, nanomedicine, photo-catalysis, and bioimaging. This review focuses on the origin and synthesis of various C-Dots with special emphasis on bacterial detection, the antibacterial effect of CDots, and their mechanism.


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