2014.12
About Instruments Today No. 201
Nanoscience and its Applications
Substrate-Mediated Localized Surface Plasmon Resonance of Gold Nanoparticles and Single Gold Nanowire [ 下載 PDF ]
Li-Yun Wang, Heh-Nan Lin
In recent years, metal nanostructures have attracted great research interests in a wide range of fields including nanophotonic devices, biosensors, etc. due to their remarkable optical properties related to localized surface plasmon resonance (LSPR). When metal nanostructures are located on a dielectric substrate, the strong substrate-mediated effect induces distinct shifts of LSPR peaks and modification of resonance modes. In this article, the substratemediated LSPR modes of gold nanoparticles and nanowires are investigated. The resonance spectra are obtained by dark-field optical microscopy and the resonance modes are analyzed by numerical simulations based on the finitedifference time-domain method. For a spherical gold nanoparticle on a dielectric substrate, the plasmon dipolar and quadrupolar modes can be observed due to the substrate-mediated coupling effect. For the single gold nanowire, only substrate-mediated dipolar coupling modes are observed.
"Using Excimer Laser Treatment to Develop Low-Cost, Ultralow Power Consumption, and High Photo- Response Cadmium Sulfide (CdS) Photoconductors" [ 下載 PDF ]
Keng-Te Lin, Hsuen-Li Chen, Yu-Sheng Lai, Shao-Chin Tseng
In this study we describe a cadmium sulfide (CdS) photoconductor that behaves as a highly sensitive and rapidly responding detector through surface treatment by an excimer laser. Such laser treatment of CdS photoconductors could be conducted in air and completed within a few seconds. The degree of crystallization of CdS films increased and their dislocation defects were removed effectively after treatment with several shots from a KrF excimer laser. At a very low bias voltage, the laser-treated CdS device provided high responsivity and detectivity. Accordingly, KrF laser annealing is a simple and rapid process that can significantly enhance the low-light detection properties of CdS. Our strategy proposed herein appears to hold great potential for ultralow-light image detection with ultralow power consumption.
Single Titanium Oxide Nanodot Ultraviolet Light Sensor Created by Atomic Force Microscopy Nanolithography [ 下載 PDF ]
Li-Yang Hong, Heh-Nan Lin
Recently, semiconductor oxide nanomaterials have drawn much research attention because of their extraordinary physical and chemical properties. Applications in a wide range of research areas have been reported, especially in the field of sensing. In this article, we report on the fabrication of a single titanium oxide nanodot (ND) nanosensor by atomic force microscopy nanolithography. A single titanium nanowire and gold contact electrodes are first created. A titanium oxide ND is then generated, which becomes a metal-oxide-metal structure, and can be used for detecting ultraviolet (UV) light. The detection mechanism is based on the desorption of oxygen molecules on the ND surface upon UV irradiation, which in turn increases the conductance. Two types of nanosensors, namely ohmic and Schottky, have been obtained by selecting oxidation regions in the nanowire and at the gold-titanium interface. The latter has a much higher sensitivity than that of the former. In addition to UV light sensing, the ND sensor can also be used for gas or chemical sensing and becomes a multi-functional nanosensor.
Low Temperatures Process of Inductively Coupled Plasma-Enhanced Atomic Layer Deposition for Fabricating Platinum Nano Thin Films as Photocatalyst [ 下載 PDF ]
Bo-Heng Liu, Hung Ji Huang
The inductively coupled plasma-enhanced atomic layer deposition (PEALD) method was used to fabricate nano Pt thin films at low temperatures with good thermal and chemical stability. The Pt thin metal films deposited on circular glass disk by PEALD can be used as reaction disk in the photocatalytic spinning disk reactor. The deposited Pt thin film has clear 4f peaks (74.3 eV (4f5/2) and 71.1 eV (4f7/2)) in X-ray photoelectron spectra measurements. The X-ray diffraction measurements showed the (111) peak of the fcc structure. The deposited Pt thin film has electric sheet resistance smaller than 12 µΩ cm for films with a thickness greater than 8 nm. The PEALD-deposited Pt thin films were chemically stable under high-temperature light illumination and could serve as catalysts under strongly alkaline conditions (pH = 12) during the long-term oxidization of ammonium ions.
Enhancing Fluorescence Detection Sensitivity [ 下載 PDF ]
Shen-Shou Max Chung, Jia-Hui Deng, Po-Lin Lin, Fu-Jen Kao, James Su
Destructive interference greatly improves the signal-to-noise ratio of fluorescence detection based on stimulated emission, and thus decreases the detection dye concentration limit. We established SE-based detection in longworking- distance settings by implementing pump-probe method with lock-in detection and destructive interference. Results show that we were able to achieve 10 times intensity ratio decrease in the probe beam with destructive interference, which corresponds to 10 times decrease of concentration detection limit. We are now developing the technique's potential for high-resolution 3D biological imaging by stimulated emission optical coherence tomography (SE-OCT), using SE fluorescence as a viable and unique contrast.
Scientifi c Identifi cation of Antiques [ 下載 PDF ]
Yong-Chien Ling
Antiquities are carriers of a nation's invisible history, culture, art, and science, possessing characteristics of national identify, non-renewable, rare, and infinite value. Herein, we use antiquities from royal family of the Shang Dynasty and the Han Dynasty as examples to describe their history, culture, and art background, highlighting that visual inspection, hand contact, and subjective experience of 'traditional identification'. We also describe the instrument technology for 'scientific identification' which is mainly based on chemistry, material, and forensic science as well as scientific attitudes. We propose the construction of communication platform between traditional identification (art and history expert) and scientific identification (technology specialist), complementing each other to verify the identification results for effective dating, authentication, and qualification of antiquities. We hope to help readers' understanding of the antiquities identification and thus provoke citizens to appreciate, love, and conservative antiquities.
Primary Mirror Alignment and Assembly for a Spaceborne Cassegrain Telescope by Using CMM [ 下載 PDF ]
Wei-Cheng Lin, Shenq-Tsong Chang, Yu-Chuan Lin, Ho-Lin Tsay, Sheng-Hsiung Chang, Chen-Peng Chang, Hsu-Pin Pan, Po-Hsuan Huang, Yu-Ting Chang, Ming-Ying Hsu, Ting-Ming Huang
The currently developing spaceborne optical remote sensing payload is a typical Cassegrain telescope with 450 mm clear aperture. The primary mirror is made of ZERODURR glass ceramic blank and lightweighted with hexagonal cell structure at a ratio about 50% for considering both effect of thermal deformation and the mass budget of the rocket. For this mirror, it is critical to reduce the astigmatism caused from the gravity effect, bonding process and the deformation from the mounting to the main structure of the telescope (main plate). In this article, the alignment of primary mirror, MGSE for the alignment and assembly process and the optical performance test for the primary mirror assembly (PMA) are presented. To get the best optical performance of PMA, the bonding position of the bipod flexure relative to primary mirror is a critical issue and shall be analyzed by finite element method (FEM) before alignment and assembly process of PMA. The mechanical shim is the interface between the bipod flexure and main plate. It is used to adjust the bonding position for the bipod flexure relative to primary mirror and also compensate the manufacture tolerances of components and differences of local co-planarity errors to prevent the local stress while bipod flexure is screwed to main plate. After primary mirror assembly process, an optical performance test refer to 'bench test' is used to analyze the astigmatism caused from the gravity effect and the deformation from the mounting or supporter. In an effort to achieve the requirement for the tolerance in PMA, the astigmatism caused from the gravity and deformation by the mounting force can be controlled within P-V 0.02λ at 632.8 nm. The consequence of these demonstrations indicates that the assembly technique for the lightweighted primary mirror meet the critical requirements for PMA of the telescope.
Design of Digital Imaging System for Slit Lamp Microscope [ 下載 PDF ]
Der-Chin Chen, Feng-Ming Yeh, Zi-Wen Lin, Lee Siak Lim
This paper using a field lens and an interface lens designed slit lamp microscope with a TV camera. Image of microscope objective through the field lens and interface lens are transmitted to the TV camera lens, and then imaged by the TV camera lens on the charge-coupled device (CCD) image sensor. Here, we use the function of zemax optics design program to multiple configuration designed, it include a television cameras of digital image and the microscopes bifunctional of slit lamp microscope. TV cameras use 3 million pixels charge-coupled device image sensor, the system required a slit length is 18 mm, the effective focal length is 11.23 mm, the spatial frequency of MTF is 80 lp/mm on the axis greater than 0.6, and the maximum field of view is greater than 0.3, the aberrations less than 5%. The designed result must be satisfy system specifications, make this slit lamp digital imaging system having a good optical quality. Because the illumination and binocular microscope are confocal and coaxial, so can reduce the system volume and easy to adjust when the assembly.
