Investigation on Solar Absorption and Thermal Emittance of Al Films Deposited by Magnetron Sputtering

A metal layer with high reflectance is widely used as the bottom mirror of smart radiation devices. Reduced solar absorption and enhanced emittance tunability are required for smart radiation devices applied in aerospace. Thus, reducing the absorption in the metal is also necessary. Here, Al films have been prepared by direct current magnetron sputtering on the fused silica substrate. The structure, morphology, and optical properties of the films have been analyzed at various deposition temperatures and deposition times. The spectrum absorption tends to increase with the increase of surface roughness due to the agglomeration and size increase of Al particles, which has been further demonstrated by the simulated results. The optimized Al film exhibits small solar absorption of 0.14 and low emittance of 0.02, which benefits the application for smart radiation devices and solar reflectors.

A proposal for wide range wavelength switching process using optical force

Optomechanical wavelength up-conversion based on optical force and core-shell scattering effects are used to control light coupling between two waveguides. This system consists of two parallel optical waveguides with 20 µm lengths suspended on a silica substrate embedded with Ag/Si/SiO2 core-shell nanoparticles. By mid-IR plane wave illumination with different intensities and different wavelengths on nanoparticles, scattering would increase and result in an improvement in attractive gradient optical force exerted on waveguides. Via bending waveguides toward each other, visible light propagating in the first waveguide would couple to another. PDMS as a polymer is used to reduce the required power for bending waveguides. Results reveal that when waveguides’ gap equilibrium is 400 nm and wavelengths of control and probe lights are 4.5 µm and 0.45 µm respectively, about 10.75 mW/µm2 power is needed to bend waveguides for total coupling of light between waveguides. The efficiency of the coupled waveguides system is %43.

Development of Pure Silica CHA Membranes for CO2 Separation

Thin pure-silica chabazite (Si-CHA) membranes have been synthesized by using a secondary growth method on a porous silica substrate. A CO2 permeance of 2.62 × 10−6 mol m−2 s−1 Pa−1 with a CO2/CH4 permeance ratio of 62 was obtained through a Si-CHA membrane crystallized for 8 h using a parent gel of H2O/SiO2 ratio of 4.6. The CO2 permeance through the Si-CHA membrane on a porous silica substrate was twice as high as that through the membrane synthesized on a porous alumina substrate, which displayed a similar zeolite layer thickness.

Low-coherence photonic method of electrochemical processes monitoring

We present an advanced multimodality characterization platform for simultaneous optical and electrochemical measurements of ferrocyanides. Specifically, we combined a fiber-optic Fabry–Perot interferometer with a three-electrode electrochemical setup to demonstrate a proof-of-principle of this hybrid characterization approach, and obtained feasibility data in its monitoring of electrochemical reactions in a boron-doped diamond film deposited on a silica substrate. The film plays the dual role of being the working electrode in the electrochemical reaction, as well as affording the reflectivity to enable the optical interferometry measurements. Optical responses during the redox reactions of the electrochemical process are presented. This work proves that simultaneous opto-electrochemical measurements of liquids are possible.

Graphene Oxide-Gold Star Construct on Triangular Electrodes for Alzheimer’s Disease Identification

Nanotechnology is playing a major role in the field of medical diagnosis, in particular with the biosensor and bioimaging. It improves the performance of the desired system dramatically by displaying higher selectivity and sensitivity. Carbon nanomaterial, gold nanostructure, magnetite nanoparticle, and silica substrate are the most popular nanomaterials greatly contributed to make the affordable and effective biosensor at low-cost. This research work is introducing a new sensing strategy with graphene oxide-constructed triangular electrodes to diagnose Alzheimer’s disease (AD). MicroRNA-137 (miRNA-137) was found as a suitable biomarker for AD, and the sensing method was established here to detect miRNA-137 on the complementary sequence. To enhance the immobilization of capture miRNA-137, gold nanostar (GNS) was conjugated with capture miRNA and immobilized on the GO-modified surface through an amine linker. This immobilization process enhanced the hybridization of the target and reaches the detection limit at 10 fM with the sensitivity of 1 fM on the linear curve with a regression coefficient of 0.9038. Further control sequences of miRNA-21 and single and triple base mismatched miRNA-137 did not show a significant response in current changes, indicating the specific miRNA-137 detection for diagnosing AD.

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

<p>Van der Waals heterojunction involving graphene (Gr) with transition metal dichalcogenides (TMDs) is regard as a promising structure for their outstanding performance in optical and optoelectronic response. The electron-hole thermalization has been deemed to be the main reason for the sub-bandgap-excitation charge transfer from Gr to TMDs. However, the role of the intricate interlayer interaction of the Gr and the TMDs still require intensive investigation. Here, we have investigated the photocarrier dynamics in 5-layer PtSe₂/Gr heterojunction by using time-resolved optical pump and terahertz probe spectroscopy. Interestingly, after photoexcitation, electron transfer from PtSe₂ to Gr in PtSe₂/Gr/substrate heterojunction has been demonstrated successfully, by contrast, no observable charge transfer occurs in the Gr/PtSe₂/substrate heterostructure. The prominent difference for the different stacking sequence between Gr and PtSe₂ can be ascribed to the effective built-in field introduced by fused silica substrate. A physical picture accounting for built-in electric field introduced by substrate has been proposed to interpret the charge transfer process in the TMD/Gr heterostructure–the substrate built-in electric field plays a dominated role for controlling the charge transfer pathway in the TMDs/Gr heterojunction. This study not only shed the light to the substrate engineering but also provide a new insight into the dynamic in Gr/TMDs heterojunction, which provides a new method to optimize the performance of photodetection. </p>

Hot Carrier Transfer in graphene/PtSe2 Heterostructure Tuned by Built-in Electric Field

<p>Van der Waals heterojunction involving graphene (Gr) with transition metal dichalcogenides (TMDs) is regard as a promising structure for their outstanding performance in optical and optoelectronic response. The electron-hole thermalization has been deemed to be the main reason for the sub-bandgap-excitation charge transfer from Gr to TMDs. However, the role of the intricate interlayer interaction of the Gr and the TMDs still require intensive investigation. Here, we have investigated the photocarrier dynamics in 5-layer PtSe₂/Gr heterojunction by using time-resolved optical pump and terahertz probe spectroscopy. Interestingly, after photoexcitation, electron transfer from PtSe₂ to Gr in PtSe₂/Gr/substrate heterojunction has been demonstrated successfully, by contrast, no observable charge transfer occurs in the Gr/PtSe₂/substrate heterostructure. The prominent difference for the different stacking sequence between Gr and PtSe₂ can be ascribed to the effective built-in field introduced by fused silica substrate. A physical picture accounting for built-in electric field introduced by substrate has been proposed to interpret the charge transfer process in the TMD/Gr heterostructure–the substrate built-in electric field plays a dominated role for controlling the charge transfer pathway in the TMDs/Gr heterojunction. This study not only shed the light to the substrate engineering but also provide a new insight into the dynamic in Gr/TMDs heterojunction, which provides a new method to optimize the performance of photodetection. </p>