scholarly journals Recent advances in measurement of the water vapour continuum in the far-infrared spectral region

2012 ◽  
Vol 370 (1968) ◽  
pp. 2637-2655 ◽  
Author(s):  
Paul D. Green ◽  
Stuart M. Newman ◽  
Ralph J. Beeby ◽  
Jonathan E. Murray ◽  
Juliet C. Pickering ◽  
...  
Keyword(s):  
Water Vapour ◽  
Spectral Band ◽  
Far Infrared ◽  
Ir Radiation ◽  
Continuum Absorption ◽  
Pure Rotation ◽  
Wide Range ◽  
Infrared Spectral ◽  
Research Aircraft ◽  
The Continuum

We present a new derivation of the foreign-broadened water vapour continuum in the far-infrared (far-IR) pure rotation band between 24 μm and 120 μm (85–420 cm −1 ) from field data collected in flight campaigns of the Continuum Absorption by Visible and IR radiation and Atmospheric Relevance (CAVIAR) project with Imperial College's Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) far-IR spectro-radiometer instrument onboard the Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft; and compare this new derivation with those recently published in the literature in this spectral band. This new dataset validates the current Mlawer–Tobin-Clough–Kneizys–Davies (MT-CKD) 2.5 model parametrization above 300 cm −1 , but indicates the need to strengthen the parametrization below 300 cm −1 , by up to 50 per cent at 100 cm −1 . Data recorded at a number of flight altitudes have allowed measurements within a wide range of column water vapour environments, greatly increasing the sensitivity of this analysis to the continuum strength.

scholarly journals Development and recent evaluation of the MT_CKD model of continuum absorption

2012 ◽  
Vol 370 (1968) ◽  
pp. 2520-2556 ◽  
Author(s):  
Eli J. Mlawer ◽  
Vivienne H. Payne ◽  
Jean-Luc Moncet ◽  
Jennifer S. Delamere ◽  
Matthew J. Alvarado ◽  
...  
Keyword(s):  
Water Vapour ◽  
Line Shape ◽  
Mathematical Formulation ◽  
Field Measurements ◽  
Continuum Absorption ◽  
Semi Empirical ◽  
Vapour Molecule ◽  
Primary Agent ◽  
The Continuum

Water vapour continuum absorption is an important contributor to the Earth's radiative cooling and energy balance. Here, we describe the development and status of the MT_CKD (MlawerTobinCloughKneizysDavies) water vapour continuum absorption model. The perspective adopted in developing the MT_CKD model has been to constrain the model so that it is consistent with quality analyses of spectral atmospheric and laboratory measurements of the foreign and self continuum. For field measurements, only cases for which the characterization of the atmospheric state has been highly scrutinized have been used. Continuum coefficients in spectral regions that have not been subject to compelling analyses are determined by a mathematical formulation of the spectral shape associated with each water vapour monomer line. This formulation, which is based on continuum values in spectral regions in which the coefficients are well constrained by measurements, is applied consistently to all water vapour monomer lines from the microwave to the visible. The results are summed-up (separately for the foreign and self) to obtain continuum coefficients from 0 to 20 000 cm −1 . For each water vapour line, the MT_CKD line shape formulation consists of two components: exponentially decaying far wings of the line plus a contribution from a water vapour molecule undergoing a weak interaction with a second molecule. In the MT_CKD model, the first component is the primary agent for the continuum between water vapour bands, while the second component is responsible for the majority of the continuum within water vapour bands. The MT_CKD model should be regarded as a semi-empirical model with strong constraints provided by the known physics. Keeping the MT_CKD continuum consistent with current observational studies necessitates periodic updates to the water vapour continuum coefficients. In addition to providing details on the MT_CKD line shape formulation, we describe the most recent update to the model, MT_CKD_2.5, which is based on an analysis of satellite- and ground-based observations from 2385 to 2600 cm −1 (approx. 4 μm).

scholarly journals Airborne and satellite remote sensing of the mid-infrared water vapour continuum

2012 ◽  
Vol 370 (1968) ◽  
pp. 2611-2636 ◽  
Author(s):  
Stuart M. Newman ◽  
Paul D. Green ◽  
Igor V. Ptashnik ◽  
Tom D. Gardiner ◽  
Marc D. Coleman ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
Weather Forecasting ◽  
Field Measurements ◽  
Atmospheric Models ◽  
Atmospheric Measurements ◽  
Continuum Absorption ◽  
Infrared Radiance ◽  
Research Aircraft ◽  
Absorption Field

Remote sensing of the atmosphere from space plays an increasingly important role in weather forecasting. Exploiting observations from the latest generation of weather satellites relies on an accurate knowledge of fundamental spectroscopy, including the water vapour continuum absorption. Field campaigns involving the Facility for Airborne Atmospheric Measurements research aircraft have collected a comprehensive dataset, comprising remotely sensed infrared radiance observations collocated with accurate measurements of the temperature and humidity structure of the atmosphere. These field measurements have been used to validate the strength of the infrared water vapour continuum in comparison with the latest laboratory measurements. The recent substantial changes to self-continuum coefficients in the widely used MT_CKD (Mlawer–Tobin–Clough–Kneizys–Davies) model between 2400 and 3200 cm −1 are shown to be appropriate and in agreement with field measurements. Results for the foreign continuum in the 1300–2000 cm −1 band suggest a weak temperature dependence that is not currently included in atmospheric models. A one-dimensional variational retrieval experiment is performed that shows a small positive benefit from using new laboratory-derived continuum coefficients for humidity retrievals.

scholarly journals Nonlinear Absorption and Far-Infrared Generation Under the Excitation of Ammonia Molecules by Strong IR Radiation

1988 ◽  
Vol 8 (2-4) ◽  
pp. 193-209 ◽  
Author(s):  
G. N. Makarov ◽  
M. V. Sotnikov ◽  
V. V. Tyakht
Keyword(s):  
Far Infrared ◽  
Laser Frequency ◽  
Rotational Transition ◽  
Pulse Radiation ◽  
Ir Radiation ◽  
Wide Range ◽  
Experimental Errors ◽  
Bottle Neck ◽  
Fitting Parameters ◽  
High Absorption

We have investigated the excitation of N14H3 molecules (the pressure is 10−2 − 1 Torr) under the effect of pulse radiation of the CO2-laser in a wide range of fluences (Φ = 10−3−10 J/cm2) and detunings of the laser frequency from the absorption lines of the vibrational-rotational transition of the ammonia band ν2. It is shown that the efficient excitation of ammonia under the influence of nonresonance IR radiation is due to the power broadening. In this case the calculation, which employs no fitting parameters, describes the experimental results within experimental errors. It is shown that the abnormally high absorption of ammonia in the case of resonance pumping is associated with an intense FIR generation which leads to elimination of the rotational bottle neck under the excitation of molecules.

Monitoring the chemical changes in fingermark residue over time using synchrotron infrared spectroscopy

2021 ◽  
Author(s):  
Rhiannon Boseley ◽  
Jitraporn Vongsvivut ◽  
Dominique Appadoo ◽  
Mark Hackett ◽  
Simon Lewis
Keyword(s):  
Water Vapour ◽  
Time Course ◽  
Far Infrared ◽  
Attenuated Total Reflection ◽  
Rate Of Change ◽  
High Spectral Resolution ◽  
Ir Radiation ◽  
Ftir Microscopy ◽  
Chemical Changes ◽  
Over Time

Degradation of fingermark residue has a major impact on the successful forensic detection of latent fingermarks. The time course of degradation has been previously explored with bulk chemical analyses, but little is known about chemical alterations at the micron-scale. Here we report the use of synchrotron-sourced attenuated total reflection-Fourier transform infrared (ATR-FTIR) microscopy to provide spatio-temporal resolution of chemical changes within fingermark droplets, as a function of time since deposition. Eccrine and sebaceous material within natural fingermark droplets were imaged on the micron scales at hourly intervals for the first 6 – 12 hours after deposition, revealing that substantial dehydration occurred within the first 8 hours. Changes to lipid material was more varied, with samples exhibiting an increase or decrease in lipid concentration due to the degradation and redistribution of this material. Across 12 donors, it was noticeable that the initial chemical composition and morphology of the droplet varied greatly, which appeared to influence on the rate of change of the droplet over time. Further, this study attempted to quantify the total water content within fingermark samples. The wide-spread nature and strength of the absorption of Terahertz/Far-infrared (THz/Far-IR) radiation by water vapour molecules were exploited for this purpose, using THz/Far-IR spectroscopy. Upon heating, water confined in natural fingermarks was evaporated and expanded in a vacuum chamber equipped with multipass optics. The amount of water vapour was then quantified by high-spectral resolution analysis, and fingermarks were observed to lose approximately 14 – 20 µg of water. The combination of both ATR-FTIR and Far-IR highlight important implications for experimental design in fingermark research, and operational practices used by law enforcement agencies.

scholarly journals The foreign-continuum absorption of water vapour in the far-infrared (50–500 cm−1)

2021 ◽  
Vol 261 ◽  
pp. 107486
Author(s):  
Aleksandra O. Koroleva ◽  
Tatyana A. Odintsova ◽  
Mikhail Yu. Tretyakov ◽  
Olivier Pirali ◽  
Alain Campargue
Keyword(s):  
Water Vapour ◽  
Far Infrared ◽  
Continuum Absorption

scholarly journals The water vapour self- and water–nitrogen continuum absorption in the 1000 and 2500 cm −1 atmospheric windows

2012 ◽  
Vol 370 (1968) ◽  
pp. 2578-2589 ◽  
Author(s):  
Yu. I. Baranov ◽  
W. J. Lafferty
Keyword(s):  
Experimental Data ◽  
Water Vapour ◽  
Continuum Model ◽  
Pure Water ◽  
Laboratory Data ◽  
The Other ◽  
Continuum Absorption ◽  
Infrared Spectrometer ◽  
Atmospheric Windows ◽  
The Continuum

The pure water vapour and water–nitrogen continuum absorption in the 1000 and 2500 cm −1 atmospheric windows has been studied using a 2 m base-length White-type multi-pass cell coupled with a BOMEM DA3-002 Fourier transform infrared spectrometer. The measurements were carried out at the National Institute of Standards and Technology (NIST, Gaithersburg, MD) over the course of several years (2004, 2006–2007, 2009). New data on the H 2 O:N 2 continuum in the 1000 cm −1 window are presented and summarized along with the other experimental results and the continuum model. The experimental data reported on the water vapour continuum in these atmospheric windows basically agree with the most reliable laboratory data from the other sources. The MT_CKD (MlawerTobinCloughKneizysDavies) continuum model significantly departs from the experimental data in both windows. The deviation observed includes the continuum magnitude, spectral behaviour and temperature dependence. In the 2500 cm −1 region, the model does not allow for the nitrogen fundamental collision-induced absorption (CIA) band intensity enhancement caused by H 2 O:N 2 collisions and underestimates the actual absorption by over two orders of magnitude. The water vapour continuum interpretation as a typical CIA spectrum is reviewed and discussed.

scholarly journals Mapping large-scale-structure evolution over cosmic times

2021 ◽  
Author(s):  
Marta B. Silva ◽  
Ely D. Kovetz ◽  
Garrett K. Keating ◽  
Azadeh Moradinezhad Dizgah ◽  
Matthieu Bethermin ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Far Infrared ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Structure Evolution ◽  
Intensity Mapping ◽  
Wide Range

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

scholarly journals Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinchao Tong ◽  
Fei Suo ◽  
Tianning Zhang ◽  
Zhiming Huang ◽  
Junhao Chu ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
High Performance ◽  
Room Temperature ◽  
Spectral Band ◽  
High Capacity ◽  
Terahertz Wave ◽  
Semiconductor Surface ◽  
Wide Range ◽  
Low Sensitivity ◽  
Air Interfaces

AbstractHigh-performance uncooled millimetre and terahertz wave detectors are required as a building block for a wide range of applications. The state-of-the-art technologies, however, are plagued by low sensitivity, narrow spectral bandwidth, and complicated architecture. Here, we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature operation. By making a nanogroove array in the grown InSb layer, strong millimetre and terahertz wave surface plasmon polaritons can be generated at the InSb–air interfaces, which results in significant improvement in detecting performance. A noise equivalent power (NEP) of 2.2 × 10−14 W Hz−1/2 or a detectivity (D*) of 2.7 × 1012 cm Hz1/2 W−1 at 1.75 mm (0.171 THz) is achieved at room temperature. By lowering the temperature to the thermoelectric cooling available 200 K, the corresponding NEP and D* of the nanogroove device can be improved to 3.8 × 10−15 W Hz−1/2 and 1.6 × 1013 cm Hz1/2 W−1, respectively. In addition, such a single device can perform broad spectral band detection from 0.9 mm (0.330 THz) to 9.4 mm (0.032 THz). Fast responses of 3.5 µs and 780 ns are achieved at room temperature and 200 K, respectively. Such high-performance millimetre and terahertz wave photodetectors are useful for wide applications such as high capacity communications, walk-through security, biological diagnosis, spectroscopy, and remote sensing. In addition, the integration of plasmonic semiconductor nanostructures paves a way for realizing high performance and multifunctional long-wavelength optoelectrical devices.

scholarly journals Continuum modeling perspectives of non-Fourier heat conduction in biological systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ákos Sudár ◽  
Gergely Futaki ◽  
Róbert Kovács
Keyword(s):  
Biological Systems ◽  
Phase Lag ◽  
Dual Phase ◽  
Continuum Modeling ◽  
Biological Origin ◽  
Ultrasound Surgery ◽  
Thermal Models ◽  
Wide Range ◽  
Fourier Heat Conduction ◽  
The Continuum

Abstract The thermal modeling of biological systems is increasingly important in the development of more advanced and more precise techniques such as ultrasound surgery. One of the primary barriers is the complexity of biological materials: the geometrical, structural, and material properties vary in a wide range. In the present paper, we focus on the continuum modeling of heterogeneous materials of biological origin. There are numerous examples in the literature for non-Fourier thermal models. However, as we realized, they are associated with a few common misconceptions. Therefore, we first aim to clarify the basic concepts of non-Fourier thermal models. These concepts are demonstrated by revisiting two experiments from the literature in which the Cattaneo–Vernotte and the dual phase lag models are utilized. Our investigation revealed that these non-Fourier models are based on misinterpretations of the measured data, and the seeming deviation from Fourier’s law originates from the source terms and boundary conditions.

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