Design and Performance Evaluation of a Deep Ultraviolet LED-Based Ozone Sensor for Semiconductor Industry Applications

Ozone (O3) is a critical gas in various industrial applications, particularly in semiconductor manufacturing, where it is used for wafer cleaning and oxidation processes. Accurate and reliable detection of ozone concentration is essential for process control, ensuring product quality, and safeguarding workplace safety. By studying the UV absorption characteristics of O3 and combining the specific operational needs of semiconductor process gas analysis, a pressure-insensitive ozone gas sensor has been developed. In its optical structure, a straight-through design without corners was adopted, achieving a coupling efficiency of 52% in the gas chamber. This device can operate reliably in a temperature range from 0 °C to 50 °C, with only ±0.3% full-scale error across the entire temperature range. The sensor consists of a deep ultraviolet light-emitting diode in a narrow spectrum centered at 254 nm, a photodetector, and a gas chamber, with dimensions of 85 mm × 25 mm × 35 mm. The performance of the sensor has been meticulously evaluated through simulation and experimental analysis. The sensor's gas detection accuracy is 750 ppb, with a rapid response time (t90) of 7 s, and a limit of detection of 2.26 ppm. It has the potential to be applied in various fields for ozone monitoring, including the semiconductor industry, water treatment facilities, and environmental research.

Recent Developments in Ozone Sensor Technology for Medical Applications

There is increasing interest in the utilisation of medical gases, such as ozone, for the treatment of herniated disks, peripheral artery diseases, and chronic wounds, and for dentistry. Currently, the in situ measurement of the dissolved ozone concentration during the medical procedures in human bodily liquids and tissues is not possible. Further research is necessary to enable the integration of ozone sensors in medical and bioanalytical devices. In the present review, we report selected recent developments in ozone sensor technology (2016–2020). The sensors are subdivided into ozone gas sensors and dissolved ozone sensors. The focus thereby lies upon amperometric and impedimetric as well as optical measurement methods. The progress made in various areas—such as measurement temperature, measurement range, response time, and recovery time—is presented. As inkjet-printing is a new promising technology for embedding sensors in medical and bioanalytical devices, the present review includes a brief overview of the current approaches of inkjet-printed ozone sensors.

The light-oxygen effect in biological cells enhanced by highly localized surface plasmon-polaritons

Here at the first time we suggested that the surface plasmon-polariton phenomenon which it is well described in metallic nanostructures could also be used for explanation of the unexpectedly strong oxidative effects of the low-intensity laser irradiation in living matters (cells, tissues, organism). We demonstrated that the narrow-band laser emitting at 1265 nm could generate significant amount of the reactive oxygen species (ROS) in both HCT116 and CHO-K1 cell cultures. Such cellular ROS effects could be explained through the generation of highly localized plasmon-polaritons on the surface of mitochondrial crista. Our experimental conditions, the low-intensity irradiation, the narrow spectrum band (<4 nm) of the laser and comparably small size bio-structures (~10 μm) were shown to be sufficient for the plasmon-polariton generation and strong laser field confinement enabling the oxidative stress observed.

A photometer array for atmospheric gravity wave measurements on the Lower Atmosphere Ionosphere Coupling Experiment (LAICE) mission

The photometer payload of the lower atmosphere ionosphere coupling experiment CubeSat mission will observe and characterize atmospheric gravity wave (AGW) propagation through the mesosphere/lower thermosphere region of Earth's atmosphere on a global scale. AGW characteristics will be measured via passive observation of airglow emission from atmospheric O₂( b 1 Σ g + ) at 762.0 nm (O₂A) and Herzberg I O₂( A 3 Σ u + - X 3 Σ g - ) at 277.0 nm (O₂HI) under nighttime conditions. The photometer payload consists of a seven-element array of photomultiplier tubes grouped into four channels, which will measure O₂A intensity at two emission wavelengths, O₂HI band intensity at a single emission wavelength, and ambient background intensity at 770.0 nm. AGW horizontal wavelength will be measured from O₂A band airglow perturbations related to rotational temperature and density, while vertical wavelength will be determined from the phase relationship between the O₂HI and O₂A bands. Wave number and wave amplitude will be used to determine the extent of energy and momentum flux associated with the wave. This is important in understanding the global distribution of high frequency waves which carry the bulk of the influence of wave energy and momentum flux from lower altitudes into the mesosphere. This can only be measured from space by nadir viewing. To our knowledge, nadir viewing of mesospheric airglow to quantify intrinsic properties of gravity waves from space has not been performed to date.

Utilization of O4 slant column density to derive aerosol layer height from a spaceborne UV-Visible hyperspectral sensor: Sensitivity and case study

The sensitivities of oxygen-dimer (O₄) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the Linearlized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the Differential Optical Absorption Spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O₄ SCD by 10⁴⁰ molecules²cm^-5, to aerosol types and optical properties are also evaluated and compared. Among the O₄ absorption bands at 340, 360, 380, and 477 nm, the O₄ absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 m for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80% of retrieved aerosol effective heights are within the error range of 1 km compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

Temperature dependent absorption cross-sections of O2-O2 collision pairs between 340 and 630 nm and at atmospherically relevant pressure

The collisions between two oxygen molecules give rise to O4 absorption in the Earth atmosphere. O4 absorption is relevant to atmospheric transmission and Earth's radiation budget. O4 is further used as a reference gas in Differential Optical Absorption Spectroscopy (DOAS) applications to infer properties of clouds and aerosols. The O4 absorption cross section spectrum of bands centered at 343, 360, 380, 446, 477, 532, 577 and 630 nm is investigated in dry air and oxygen as a function of temperature (203-295 K), and at 820 mbar pressure. We characterize the temperature dependent O4 line shape and provide high precision O4 absorption cross section reference spectra that are suitable for atmospheric O4 measurements. The peak absorption cross-section is found to increase at lower temperatures due to a corresponding narrowing of the spectral band width, while the integrated cross-section remains constant (within <3%, the uncertainty of our measurements). The enthalpy of formation is determined to be ΔH(250) = -0.12 ± 0.12 kJ mol(-1), which is essentially zero, and supports previous assignments of O4 as collision induced absorption (CIA). At 203 K, van der Waals complexes (O(2-dimer)) contribute less than 0.14% to the O4 absorption in air. We conclude that O(2-dimer) is not observable in the Earth atmosphere, and as a consequence the atmospheric O4 distribution is for all practical means and purposes independent of temperature, and can be predicted with an accuracy of better than 10(-3) from knowledge of the oxygen concentration profile.

Optical extinction monitor using cw cavity enhanced detection

We present details of an apparatus capable of measuring optical extinction (i.e., scattering and/or absorption) with high precision and sensitivity. The apparatus employs one variant of cavity enhanced detection, specifically cavity attenuated phase shift spectroscopy, using a near-confocal arrangement of two high reflectivity (R approximately 0.9999) mirrors in tandem with an enclosed cell 26 cm in length, a light emitting diode (LED), and a vacuum photodiode detector. The square wave modulated light from the LED passes through the absorption cell and is detected as a distorted wave form which is characterized by a phase shift with respect to the initial modulation. The amount of that phase shift is a function of fixed instrument properties-cell length, mirror reflectivity, and modulation frequency-and of the presence of a scatterer or absorber (air, particles, trace gases, etc.) within the cell. The specific implementation reported here employs a blue LED; the wavelength and spectral bandpass of the measurement are defined by the use of an interference filter centered at 440 nm with a 20 nm wide bandpass. The monitor is enclosed within a standard 19 in. rack-mounted instrumentation box, weighs 10 kg, and uses 70 W of electrical power including a vacuum pump. Measurements of the phase shift induced by Rayleigh scattering from several gases (which range in extinction coefficient from 0.4-32 Mm(-1)) exhibit a highly linear dependence (r(2)=0.999 97) when plotted as the co-tangent of the phase shift versus the expected extinction. Using heterodyne demodulation techniques, we demonstrate a detection limit of 0.04 Mm(-1) (4 x 10(-10) cm(-1)) (2sigma) in 10 s integration time and a base line drift of less than +/-0.1 Mm(-1) over a 24 h period. Detection limits decrease as the square root of integration time out to approximately 150 s.

The Water Vapor Spectrum in the Region 8600-15 000 cm(-1): Experimental and Theoretical Studies for a New Spectral Line Database

New laboratory measurements are presented for the near-infrared and visible spectrum (8600-15 000 cm(-1)) of water vapor. Spectral line parameters, principally intensities and air-broadening coefficients, are derived from Fourier transform spectroscopic measurements at high resolution (0.03 cm(-1)), a range of optical path lengths (5-513 m), and temperatures of both 252 and 296 K. Experimental line parameters are derived for 5034 assigned transitions and thorough error analysis shows parameter errors of less than 2.5% for one-third and less than 5% for over half of the lines. Calculated spectra, derived using these line parameters, reproduce the original spectra to within 2%. A comparison of the line intensities with those in the HITRAN-96 database identifies large errors in the latter with random differences that exceed a factor of two for many lines, and systematic differences between 6 and 26% depending on the water band under consideration. The recent corrections to the HITRAN database by Giver et al. (J. Quant. Spectrosc. Radiat. Transfer 66, 101-105 (2000)) do not remove these discrepancies and the differences change to 6-38%. The new data are expected to substantially increase the calculated absorption of solar energy due to water vapor in climate models. Copyright 2001 Academic Press.

Molecular Constants for the v=0, b(1)Sigma(g)(+) Excited State of O(2): Improved Values Derived from Measurements of the Oxygen A-Band Using Intracavity Laser Spectroscopy

High-resolution intracavity laser spectroscopy (ILS) absorption measurements have been made on the b-X oxygen electronic transition (the A-band) which has bandheads occurring in the region of 13 165 cm(-1). The positions of the lines were determined to an accuracy that is based on calibration with I(2) absorption lines using the Laboratoire Aimé Cotton (Orsay) Atlas as reference. Based on the ILS measurements and the more accurately determined positions given by L. R. Brown and C. Plymate (J. Mol. Spectrosc. 199, 166-179 (2000)) and with the (3)Sigma(g)(-) ground state molecular constants fixed at the values determined by G. Rouillé et al. (J. Mol. Spectrosc. 154, 372-382 (1992)), the following values (in cm(-1)) were found for the molecular constants: T(0)=13122.2524(1); B(0)=1.391244(2); D(0)=5.352(4)x10(-6); and H(0)=-1.2(2)x10(-11). These results are compared with values derived from fits of the line positions listed in several other studies of this transition. Copyright 2001 Academic Press.

Experimental Line Parameters of the Oxygen A Band at 760 nm

To support atmospheric remote sensing applications, line positions, intensities, self- and nitrogen-broadened linewidths and their temperature dependences and pressure-induced shifts in line positions at room temperature were measured up to J' and N' = 22 for the oxygen A band at 13 122 cm(-1). Line intensities were obtained with 1% precisions and 2% absolute accuracies using absorption spectra recorded at Doppler-limited (0.02 cm(-1)) resolution with the McMath Fourier transform spectrometer (FTS) located at Kitt Peak National Observatory/National Solar Observatory in Arizona. The oxygen line positions were calibrated using near-infrared transitions of the 2-0 and 3-0 bands of CO as secondary standards. The intensities and positions of seven H(2)O lines near 13 900 cm(-1) were also remeasured to validate the FTS performance. The O(2) intensities fell within 1% of the values currently assumed for the molecular databases, but it was found that broadening coefficients and line positions should be revised for the A band of molecular oxygen. Copyright 2000 Academic Press.

Visible absorption bands of the (O2)2 collision complex at pressures below 760 Torr

The collision-induced absorption of oxygen in the 540-650-nm wavelength region has been measured ata pressure range from 0 to 730 Torr at T 5 294 K. Pressure-dependent cross sections of the X 3Sigmag(+)+X 3Sigmag alpha 1Deltag(nu =0) + alpha 1Deltag(nu = 1 ) and X 3Simag(+)+ X 3Sigmag+--> alpha 1Deltag(nu =0) + 1 alpha 1Deltag (nu = 0) transitions have been determined by means of cavity-ringdown spectroscopy. Contributions of the overlapping g and d bands of O2 have been evaded, and Rayleigh extinction has been taken into account.