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Vibrational Microspectroscopy for the Analysis of Surfaces and Particles on Surfaces
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
When in situ studies are not conceivable due to sampling or instrumental factors, sometimes the microscopic surface component under study can be physically or chemically removed and then prepared for transmission infrared microspectroscopy. Consider the following example involving the chemical removal of a microscopic blemish found on the surface a cigarette paper.12 The area around the blemish was washed with methylene chloride onto an infrared window, and the infrared spectrum of a 20 × 100 μm area of the residue concentrate was obtained using an infrared microscope accessory in the transmission mode. The spectrum of the residue indicated an aliphatic hydrocarbon that is characteristic of lubricants, and its identification allowed the source of the blemish to be traced to a leaking oil line involved in the manufacture of the paper.
Crystalline and Two-Phase Materials
Published in Solomon Musikant, Optical Materials, 2020
Diamond is an exotic crystalline material. The well-known diamond crystal structure is shown in Fig. 3.7. A single crystal natural diamond has been used as an infrared window in an IR sensor for one of the probes to the planet Venus. Diamond does not have to be of gem quality to be optically useful. Suitable natural diamonds are available and, although expensive, these are much cheaper than gem quality stones. Diamond’s outstanding optical property is its longwave cutoff, beyond 200 μm. Diamond is a cubic crystal and has no intrinsic birefringence. However, internal strains are manifested as birefringence (strain birefringence).
Principles of Polymer Optical Fibers
Published in Marcelo Martins Werneck, Regina Célia da Silva Barros Allil, Plastic Optical Fiber Sensors, 2019
Ricardo Oliveira, Lúcia Bilro, Rogério N. Nogueira
As described previously, SM behavior in SI-POFs has only been reported at the infrared window. This is due to the compromise between the core radius and refractive index contrast that need to be balanced in order to have a normalized frequency lower than 2.405, making it particularly difficult when the operating wavelength is shorter. One clear advantage of mPOFs when compared with SI-POFs is the ease of the manipulation of the fiber structure. Therefore, by manipulating the hole dimensions and their arrangement, it is possible to easily produce a fiber with SM behavior at the visible region (van Eijkelenborg et al., 2001; Zagari et al., 2004).
Variability and trends in land surface longwave radiation fluxes from six satellite and reanalysis products
Published in International Journal of Digital Earth, 2023
Jianglei Xu, Shunlin Liang, Tao He, Han Ma, Yufang Zhang, Guodong Zhang, Hui Liang
The CERES instrument provides TOA radiometric observations from three broadband channels: a shortwave channel (0.3–5 μm), total channel (0.3–200 μm), and infrared window channel (8–12 μm) (Wielicki et al. 1996). These observations provide an accurate constraint for CERES-SYN TOA radiation derived using scene-dependent angular directional models. To estimate the daily mean longwave radiation flux, the CERES-SYN product used cloud profile data from Terra and Aqua MODIS cloud observations, Cloudsat radar, and CALIPSO Lidar profile data to determine cloud characteristics (Kato et al. 2011; Minnis et al. 2008). These cloud products were derived from NASA’s polar orbiting satellite cluster. Considering that polar orbiters hardly detect diurnal variations in clouds, geostationary satellite-derived cloud properties were additionally used to improve their capability (Doelling et al. 2013). CERES-SYN SLR flux data were calculated using the Fu–Liou radiative transfer model based on these cloud profile data (Doelling et al. 2016). The CERES-SYN (Edition 4.1) SLR dataset used in this study is a gap-free product, with an hourly temporal resolution and 1° spatial resolution from March 2000 to December 2021.
Optical properties of diamond-like carbon films prepared by pulsed laser deposition onto 3D surface substrate
Published in Surface Engineering, 2021
Yimin Lu, Guojun Huang, Sai Wang, Lin Xi, Chaowei Mi, Shuyun Wang, Yong Cheng
In this research, PLD (pulsed laser deposition), one of the PVD technologies, was tried to prepare optical DLC film onto the 3D curved silicon substrate. Silicon is a kind of MIR window in the infrared field, and the protective and reflective DLC film for the curved infrared window has the potential values in the infrared detection like deep space exploration. However, the spatial distribution of the plume induced by laser is believed to be a forward-directed cone-shape, which is disadvantageous seriously to grow uniform film. Therefore, a novel deposition setup that could carry out three-dimensional motion was designed and founded to reduce this adverse effect. The measurements indicated that this deposition setup could reduce the thickness deviation on the 3D curved surface based on the optimized simulation from the theoretical model, and the DLC film was homogeneous. This reported research offered a way to resolve the problem of the non-uniformity in the PLD-grown coatings and improved the practicability of the PLD technology in the optical field.
Research on heat reflective coating technology of asphalt pavement
Published in International Journal of Pavement Engineering, 2022
Yuanzhao Chen, Zhenxia Li, Siqing Ding, Xiaolan Yang, Tengteng Guo
Functional fillers refer to the materials that are involved in cooling function in the coating, and play a decisive role in the heat reflection performance of the coating. As the main functional filler, Titanium dioxide has the characteristics of high refractive index, strong light scattering ability, high UV shielding, strong stability and oxidation resistance, high reflectance ratio to near-infrared radiation and significant shielding of solar thermal radiation. However, in view of the high cost of titanium dioxide, diatomite and hollow glass beads, which also have a cooling function, were used to replace some titanium dioxide in the coating to reduce costs. Due to the weak absorption ability of the atmosphere in the wavelength range of 8 ∼ 13.5 μm, and the infrared radiation intensity in the atmosphere is mainly derived from the radiation of water vapour, CO2, O3 and suspended particles in the atmosphere by studying the relationship between the infrared radiation intensity and the wavelength and direction, in which the absorption ability of CO2 and water vapour in the wavelength range of 8 ∼ 13.5 μm is weak, so the external radiation in this range has a strong penetrating power on the atmosphere, which can send energy directly to the outer space; this wavelength range is called ‘infrared window’ or ‘atmospheric window’ in related fields (Li 2016). According to Kirchhoff’s law, a good absorber must also be a good emitter. The absorption peak of silica at 1100 cm−1 (wavelength about 9 μm) is strong and wide so that it can absorb the solar radiation in the wavelength range of 8 ∼ 13.5 μm, and then emit it to the external space through the atmospheric window, to reduce the temperature of asphalt pavement and alleviate the heat island effect in cities. Thus, silica was also added as the functional filler. Additives