This PDF file contains the front matter associated with SPIE Proceedings Volume 12201, including the Title Page, Copyright information, Table of Contents, and Conference Committee Page.

Hollow cathode plasmas are common extreme ultraviolet (EUV) lamps used for material characterization. However, the relatively high pressure of the plasma can affect downstream instruments, as well as absorb the EUV. EUV windows are difficult to fabricate due to EUV’s strong interaction with all materials. We present a carbon nanotube (CNT) microfabricated window composed of multiple high aspect-ratio columns in parallel. The open areas allow wide bandpass transmission, while the walls restrict gas flow. We model the CNT window transmission as a weight function on the light from of a Mcpherson 629-like hollow cathode helium plasma in visible wavelengths. We model the CNT window differential pumping as a series of columns between two chambers of different pressures.

Graphite and diamond are the two most common allotropes of solid carbon. Graphite is abundant in nature, diamond is much less abundant and has very much demanded characteristics such as its hardness and its properties as semiconductor: wide bandgap (5.45 eV) and high thermal conductivity (22W/cmK). Chemical vapor deposition (CVD) is often used by the industry to grow diamonds. However, nanodiamonds can also be produced by inducing the phase transition from the sp² layered structure of graphite to the sp³ cubic structure of diamond using UV radiation. The emission of photoelectrons results in a redistribution of the electrons from the graphite π bands to the interlayer band and a distortion of the graphitic lattice that drives at the sp² to sp³ transition. In this contribution, further details on the distribution and structure of the nanodiamonds produced by this means are provided.

The high blood glucose levels associated with diabetes affect various cells and proteins in the body. In response to high blood glucose collagen and keratin proteins experience glycation. This work aims to establish if the intrinsic fluorescence of collagen and keratin could be used to monitor the glycation of said compounds, and thus offer an alternative method to monitoring long term glycaemic control. We have studied the evolution of the intrinsic fluorescence of both compounds in response to glucose in vitro, using steady state and time-resolved fluorescence spectroscopy techniques. Changes in the intrinsic fluorescence of both collagen and keratin were observed. For collagen, contrary to the traditional fluorescence intensity decay measurement at arbitrarily selected excitation and detection wavelengths, we conducted systematic wavelength- and time-resolved measurements to achieve time-resolved emission spectra (TRES). These showed changes in the intrinsic fluorescence kinetics, caused by both collagen aggregation and glycation. In keratin, the addition of glucose caused an increase in the fluorescence intensity at the characteristic wavelength of 460 nm, due to faster formation of new cross-links. The results also suggest that glucose may cause the formation of two new fluorescent complexes with peak fluorescence at ~525 nm and ~575 nm. In conclusion, monitoring the intrinsic fluorescence of collagen or keratin could be used as a method to monitor long term glycaemic control in patients with diabetes.

In the current study, we report the growth of rare earth Er-doped Ga₂O₃ nanostructures on Ga₂O₃- seeded Si substrate by employing chemical bath deposition (CBD) and RF magnetron sputtering techniques. A thin layer (~50 nm) of Ga₂O₃ is deposited on p-Si substrate with the optimize deposition temperature and Ar:O₂ flow rate to create a favourable template for growing high quality nanostructures on it. After growing the Er-doped Ga₂O₃ nanostructures, thermal annealing is performed at 800°C to achieve thermodynamically stable β-phase of Ga₂O₃. The effect of Er doping on structural, optical and luminescence properties of Ga₂O₃ nanostructures has been successfully investigated by employing FEGSEM, XRD, UV-VIS and PL. XRD studies confirms the polycrystalline β-phase monoclinic structure of Ga₂O₃ for both undoped and Er-doped nanostructures with dominant <-111> plane. Top view images of FEGSEM depict the large area growth of rod/wire like structures of Ga₂O₃ on thin Ga₂O₃ deposited Si substrate and confirm the formation of heterojunction between Ga₂O₃ and Si. Deconvoluted PL spectra shows two broad peaks within the wavelength range of 260 nm to 460 nm, which are associated with near band emission and three different types of oxygen vacancies present in β-Ga₂O₃, respectively. The change in optical absorbance and corresponding energy band gap of undoped and Er-doped nanostructures are analysed in detail by using UV-VIS spectroscopy and such energy bandgap values lie with the range of 4.4 eV-4.7 eV. Finally, current-voltage characteristics of undoped and Er-doped Ga₂O₃/Si heterojunction has been studied and such heterojunctions can be a potential candidate for the fabrication of several optoelectronic devices as well as high power applications.

Recently the application of far ultraviolet (UVC 200-230nm) optical radiation for disinfection of occupied spaces has seen a growing interest. Filtered excimer krypton-chloride (KrCl) lamps, which emit predominantly at 222 nm, have been shown to provide similar or better pathogen reduction rates, while being safe for human eye and skin exposure at much higher dose levels than the typical 254 nm radiation. This opens new opportunities to provide disinfection of air and surfaces while people are present. The installations of 222 nm light fixtures are professionally planned using adopted light planning software. In order to achieve reasonable accurate radiation distribution models and predict the applied UV dose levels, the reflectance of the materials found in the space needs to be considered. Unfortunately, there is very little literature on the reflectance of interior building materials in the UV. The paper presents a simplified setup for collecting reflectance data, using an existing polytetrafluoroethylene (PTFE) sphere, a 222 nm radiometer, and a filtered excimer KrCl lamp. Common building materials have been investigated with this method and most of them showed a diffuse reflectance of about 10%. Reflectance measurements were also made by the National Institute for Standards and Technology (NIST) for the purpose of validating the method. Advantages and disadvantages of the applied method are discussed.

In this paper, a direct and cost-effective sol-gel method to produce stable titanium dioxide and titanium oxynitride photoresists is described. This approach is compatible with many photolithographic techniques. We show that laser interference lithography and nanosphere lithography can be used, respectively, to obtain homogeneous TiO₂ diffraction gratings and periodic nanopillars over large areas. Further developments permit to transform TiO₂ microstructured based sol-gel to TiN metallic microstructured layer, with good optical properties, by using an innovative rapid thermal nitridation process, which opens the way towards plasmonics and NIR filters based on periodic metallic microstructured layers. Further technological processes were conducted to produce micro and nanostructured TiO₂ and TiN layers from a NanoImprint approach.
This work demonstrates the versatility of this complete process of soft chemistry new process of patterning TiO₂ and TiN thin films avoiding expensive processes (etching, lift-off…) while preserving their diffractive properties and a high thermal stability, up to 1000°C. It is thus compatible to various types of substrates (of different shape and size). These results open up the opportunity to develop a cost-effective and low time-consuming approach to address different fields of cutting-edge applications (metasurfaces, sensors, luxury and decorative industry…).

Gallium oxide (Ga2O3) is an emerging wideband semiconductor which can be utilize in solar-blind photodetector and high power electronics application. Having a large bandgap and high breakdown field makes Ga2O3 material suitable for these device applications. However, the physical and the optical properties of Ga2O3 can be tailored by changing the annealing ambient and temperature, and understanding how the annealing atmosphere can affect these properties is crucial for designing a next generation optoelectronic devices. Moreover, the presence of defects and impurities can also affect the device parameters. Thus, in this work, we have investigated the influence of post deposition annealing atmosphere on the morphological, structural, and optical properties of Ga2O3 films. The prepared samples were further went through thermal annealing at 800°C for 30 mins in nitrogen (N2), and oxygen (O2) ambient to achieve β-phase of Ga2O3. The structural properties of all the samples were studied by atomic force microscopy, and x-ray diffraction while the optical properties were studies by UV-visible, and photoluminescence spectroscopy. We have found monoclinic β-phase in the polycrystalline annealed Ga2O3 samples. The optical band gap of films were increased after annealing and highest band gap is obtained to 5.44eV in N2 annealed sample as compared to as-deposited sample (4.56eV). A broad photoluminescence spectrum ranged from 350 to 480 nm was observed, which further deconvoluted in three peaks at around 378 nm, 399 nm, and 422 nm in as-deposited sample. The same peaks with broad photoluminescence spectrum was found to be blue shifted for annealed samples as compared to the as-deposited. This study will open a new direction in future deep-UV photodetector fabrication.

NASA’s Dragonfly mission will sample surface materials from multiple sites on Saturn’s largest moon, Titan, in exploration of its potential for prebiotic chemistry. We are developing and delivering a compact pulsed UV laser transmitter, developed in-house at NASA’s Goddard Space Flight Center, capable of directing programmable 266 nm pulse energies to a small sample of surface material for laser desorption mass spectrometry (LDMS) performed by the on-board Dragonfly Mass Spectrometer (DraMS). The mail goal for this effort was to develop a flight-capable, two-part design, employing a remotely located fiber coupled pumping source, and a UV transmitter unit that can operate in short bursts with minimal change in laser pulse characteristics such as beam quality, pointing, energy, and pulse width. The DraMS UV source will require a 7+ year transit to the Saturn system; where upon deployment on Titan’s surface, must demonstrate a combination of survivability, reliability, operational capability, and performance yet developed in a flight-qualified solid-state laser transmitter. Once Dragonfly is safely operational, the Titan Hydrocarbon Analysis Nanosecond Optical Source (THANOS) UV laser will perform for 3+ years in Titan’s extreme surface and atmospheric conditions in several locations.