scholarly journals Bandgap Engineering and Near-Infrared-II Optical Properties of Monolayer MoS2: A First-Principle Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Ke Yang ◽  
Tianyu Liu ◽  
Xiao-Dong Zhang
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Infrared Region ◽  
Bandgap Engineering ◽  
Vacancy Defects ◽  
Fundamental Properties ◽  
Two Dimensional Materials ◽  
Poor Stability ◽  
Crucial Characteristic

The fluorescence-based optical imaging in the second near-infrared region (NIR-II, 1,000–1,700 nm) has broad applications in the biomedical field, but it is still difficult to find new NIR-II fluorescence materials in the two dimension. As a crucial characteristic of the electronic structure, the band structure determines the fundamental properties of two-dimensional materials, such as their optical excitations and electronic transportation. Therefore, we calculated the electronic structures and optical properties of different crystalline phases (1T phase and 2H phase) of pure monolayer MoS2 films and found that the 1T phase has better absorption and thus better fluorescence in the NIR-II window. However, its poor stability makes the 1T-phase MoS2 less useful in vivo bioimaging. By introducing vacancy defects and doping with foreign atoms, we successfully tuned the bandgap of the monolayer 2H-MoS2 and activated it in the NIR-II. Our results show that by engineering the vacancy defects, the bandgap of the 2H phase can be tailored to around 1 eV, and there are three candidates of vacancy structures that exhibit strong absorption in the NIR-II.

In Vivo Fluorescence Imaging with Ag2S Quantum Dots in the Second Near-Infrared Region

2012 ◽  
Vol 51 (39) ◽  
pp. 9818-9821 ◽  
Author(s):  
Guosong Hong ◽  
Joshua T. Robinson ◽  
Yejun Zhang ◽  
Shuo Diao ◽  
Alexander L. Antaris ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Fluorescence Imaging ◽  
Near Infrared ◽  
Infrared Region ◽  
In Vivo Fluorescence ◽  
In Vivo Fluorescence Imaging ◽  
Near Infrared Region ◽  
Ag2s Quantum Dots

scholarly journals Multi-layered tissue head phantoms for noninvasive optical diagnostics

2015 ◽  
Vol 08 (03) ◽  
pp. 1541005 ◽  
Author(s):  
M. S. Wróbel ◽  
A. P. Popov ◽  
A. V. Bykov ◽  
M. Kinnunen ◽  
M. Jędrzejewska-Szczerska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Optical Measurement ◽  
Human Head ◽  
Medical Diagnostics ◽  
Optical Parameters ◽  
Measurement Systems ◽  
Tissue Phantoms ◽  
Optical And Mechanical Properties

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate specific tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with specific optical properties of each layer. However, such a structure is not always addressed in the present-day phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coefficient [Formula: see text] and absorption coefficient μa) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide ( ZnO ) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching was found between optical properties of phantoms and the corresponding values found in the literature.

scholarly journals Optical properties of spray pyrolysis deposited Cds:Al thin films

2015 ◽  
Vol 39 (1) ◽  
pp. 25-30 ◽  
Author(s):  
A Hasnat Rubel ◽  
J Podder
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Spray Pyrolysis ◽  
Near Infrared ◽  
Visible Region ◽  
Cadmium Sulphide ◽  
Infrared Region ◽  
Photo Detectors ◽  
Direct Energy ◽  
Academy Of Sciences

Aluminium doped cadmium sulphide thin films were prepared on glass substrate using aqueous solution of cadmium sulphide and thiourea salts by spray pyrolysis deposition (SPD) technique. Its optical properties were analyzed as a function of doping concentration. The direct energy band-gap of Al-doped CdS films was estimated in the range of 2.25 to 2.48 eV. The optical spectra of Cd1-xAlxS ternary system exhibit high absorption near visible region and transmission throughout the near-infrared region (600 - 1200 nm). Thus so obtained hetero-junction films are suitable for fabrication of photo detectors, solar cells and other optoelectronics devices.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 25-30, 2015

Influence of Blood Glucose Level on the Scattering Coefficient of the Skin in Near-Infrared Spectroscopy

2011 ◽  
Author(s):  
Sachiko Kessoku ◽  
Katsuhiko Maruo ◽  
Shinpei Okawa ◽  
Kazuto Masamoto ◽  
Yukio Yamada
Keyword(s):  
Optical Properties ◽  
Infrared Spectroscopy ◽  
Blood Glucose ◽  
Blood Glucose Level ◽  
Glucose Level ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Monitoring Methods ◽  
Absorbance Spectra

Various non-invasive glucose monitoring methods using near-infrared spectroscopy have been investigated although no method has been successful so far. Our previous study has proposed a new promising method utilizing numerically generated absorbance spectra instead of the experimentally acquired absorbance spectra. The method suggests that the correct estimation of the optical properties is very important for numerically generating the absorbance spectra. The purpose of this study is to measure the change in the optical properties of the skin with the change in the blood glucose level in vivo. By measuring the reflectances of light incident on the skin surface at two distances from the incident point, the optical properties of the skin can be estimated. The estimation is a kind of the inverse problem based on the simulation of light propagation in the skin. Phantom experiments have verified the method and in vivo experiments are to be performed.

Synthesis and optical properties of emission-tunable PbS/CdS core–shell quantum dots for in vivo fluorescence imaging in the second near-infrared window

RSC Advances ◽  
2014 ◽  
Vol 4 (77) ◽  
pp. 41164-41171 ◽  
Author(s):  
Yoshikazu Tsukasaki ◽  
Masatoshi Morimatsu ◽  
Goro Nishimura ◽  
Takao Sakata ◽  
Hidehiro Yasuda ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Fluorescence Imaging ◽  
Near Infrared ◽  
Core Shell ◽  
Cds Quantum Dots ◽  
In Vivo Fluorescence ◽  
In Vivo Fluorescence Imaging ◽  
Infrared Window

This paper describes the synthesis and optical properties of PbS/CdS quantum dots for in vivo fluorescence imaging.

scholarly journals Optical investigation of bovine grey and white matters in visible and near-infrared ranges

2021 ◽  
Vol 27 (1) ◽  
pp. 99-107
Author(s):  
Ali Shahin ◽  
Wesam Bachir ◽  
Moustafa Sayem El-Daher
Keyword(s):  
Optical Properties ◽  
Absorption Coefficient ◽  
Wavelength Range ◽  
Grey Matter ◽  
Near Infrared ◽  
Biological Tissues ◽  
Integrating Sphere ◽  
Visible Range ◽  
Optical Investigation

Abstract Introduction: Due to enormous interests for laser in medicine and biology, optical properties characterization of different tissue have be affecting in development processes. In addition, the optical properties of biological tissues could be influenced by storage methods. Thus, optical properties of bovine white and grey tissues preserved by formalin have been characterized over a wide wavelength spectrum varied between 440 nm and 1000 nm. Materials and Methods: To that end, a single integrating sphere system was assembled for spectroscopic characterization and an inverse adding-doubling algorithm was used to retrieve optical coefficients, i.e. reduced scattering and absorption coefficients. Results: White matter has shown a strong scattering property in comparison to grey matter. On the other hand, the grey matter has absorbed light extensively. In comparison, the reduced scattering profile for both tissue types turned out to be consistent with prior works that characterized optical coefficients in vivo. On the contrary, absorption coefficient behavior has a different feature. Conclusion: Formalin could change the tissue’s optical properties because of the alteration of tissue’s structure and components. The absence of hemoglobin that seeps out due to the use of a formalin could reduce the absorption coefficient over the visible range. Both the water replacement by formalin could reduce the refractive index of a stored tissue and the absence of hemoglobin that scatters light over the presented wavelength range should diminish the reduced scattering coefficients over that wavelength range.

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