scholarly journals First observation of the magnetic dipole CO2 absorption band at 3.3 μm in the atmosphere of Mars by the ExoMars Trace Gas Orbiter ACS instrument

2020 ◽  
Vol 639 ◽  
pp. A142 ◽  
Author(s):  
A. Trokhimovskiy ◽  
V. Perevalov ◽  
O. Korablev ◽  
A. F. Fedorova ◽  
K. S. Olsen ◽  
...  
Keyword(s):  
Absorption Band ◽  
Magnetic Dipole ◽  
Atmospheric Chemistry ◽  
Electric Quadrupole ◽  
Optical Path Length ◽  
Trace Gas ◽  
First Year ◽  
Co2 Absorption ◽  
Absorption Bands ◽  
Atmospheric Species

The atmosphere of Mars is dominated by CO2, making it a natural laboratory for studying CO2 spectroscopy. The Atmospheric Chemistry Suite (ACS) on board the ExoMars Trace Gas Orbiter uses solar occultation geometry to search for minor atmospheric species. During the first year of ACS observations, the attention was focused on the spectral range covering the methane ν3 absorption band, 2900–3300 cm−1, which has previously been observed on Mars. No methane was detected by ACS; instead, an improvement of the data processing has led to the identification of 30 weak absorption lines that were missing from spectroscopic databases. Periodic series of absorptions up to ~1.6% deep are observed systematically around the position of the methane Q-branch when the line of sight penetrates below 20 km (creating an optical path length of 300–400 km, with an effective pressure of a few millibar). The observed frequencies of the discovered lines match theoretically computed positions of the P-, Q-, and R-branches of the magnetic dipole and electric quadrupole 01111-00001 (ν2 + ν3) absorption bands of the main CO2 isotopologue; neither band has been measured or computed before. The relative depths of the observed spectral features support the magnetic dipole origin of the band. The contribution of the electric quadrupole absorption is several times smaller. Here we report the first observational evidence of a magnetic dipole CO2 absorption.

First observation of the magnetic dipole CO2 main isotopologue absorption band at 3.3 µm in the atmosphere of Mars by ACS ExoMars

2020 ◽  
Author(s):  
Alexander Trokhimovskiy ◽  
Valery Perevalov ◽  
Oleg Korablev ◽  
Anna Fedorova ◽  
Kevin S. Olsen ◽  
...  
Keyword(s):  
Absorption Band ◽  
Magnetic Dipole ◽  
Atmospheric Chemistry ◽  
Optical Path ◽  
Trace Gas ◽  
First Year ◽  
Co2 Absorption ◽  
Methane Absorption ◽  
Solar Occultation ◽  
Natural Laboratory

<p>The CO2-dominated atmosphere of Mars is an ideal natural laboratory to study the spectroscopy of this gas. The Atmospheric Chemistry Suite (ACS) package onboard the ExoMars 2016 Trace Gas Orbiter (TGO) sounds the atmosphere in solar occultation, allowing, in case of a very clear atmosphere, reaching an optical path of 300-400 km at an effective pressure of a few millibars. During the first year of ACS observations, the focus of attention was kept on the spectral range covering the fundamental methane absorption band, 2900-3300 cm–1. No methane was detected, while a further improvement of the data processing led to the identification of weak periodic absorption lines, missing from spectroscopic databases. The observed frequencies of the lines match theoretically computed positions of the Q, P and R branches of the magnetic dipole 01111-00001 absorption band of the main CO2 isotopologue, never measured or computed before. We will report the first observational evidence of a magnetic dipole CO2 absorption. The data analysis was supported by RSF (project No. 20-42-09035).</p>

scholarly journals Cavity Ring-Down Spectroscopy for Molecular Trace Gas Detection Using A Pulsed DFB QCL Emitting at 6.8 µm

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 74
Author(s):  
Komlan S. Gadedjisso-Tossou ◽  
Lyubomir I. Stoychev ◽  
Messanh A. Mohou ◽  
Humberto Cabrera ◽  
Joseph Niemela ◽  
...  
Keyword(s):  
Optical Path Length ◽  
High Energy ◽  
High Resolution Spectroscopy ◽  
Trace Gas ◽  
Absorption Bands ◽  
Ir Radiation ◽  
Cavity Ring Down Spectroscopy ◽  
Spectral Performance ◽  
Partial Interference ◽  
Cavity Ring Down

A trace gas sensor based on pulsed cavity ring-down spectroscopy (CRDS) was developed for measurement of the ν4 fundamental vibrational band of ammonia (NH3) centered at 1468.898 cm−1. A pulsed distributed feedback quantum cascade laser (DFB-QCL) operating at 6.8 µm (1470.58 cm−1) quite well covered the absorption band of the ammonia and strong fundamental vibrational absorption bands of different molecular gases in this unexplored region. The cavity was partially evacuated down to 0.4 Atm by a turbo-molecular pump to reduce the partial interference between the NH3 spectra and water near the absorption peak of ammonia. A sensitivity of nine parts per billion was reached for a measurement time of 120 s as well as an optical path length of 226 m. The device demonstrated high spectral performance and versatility due to its wide tuning range, narrow linewidth, and comparatively high-energy mid-IR radiation in the relatively unexplored 6.8 µm region, which is very important for high-resolution spectroscopy of a variety of gases.

Temperature and CO2 density distribution in Mars upper atmosphere from the ACS-MIR / TGO solar occultations at 2.7 μm absorption band

2020 ◽  
Author(s):  
Denis Belyaev ◽  
Anna Fedorova ◽  
Alexander Trokhimovskiy ◽  
Oleg Korablev ◽  
Franck Montmessin ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Molecular Diffusion ◽  
Iteration Scheme ◽  
Resolving Power ◽  
Trace Gas ◽  
Spectral Interval ◽  
Absorption Bands ◽  
The Moment ◽  
Infrared Channel

<p>The mid-infrared channel of the Atmospheric Chemistry Suite (ACS-MIR) is a cross-dispersion echelle spectrometer dedicated to solar occultation measurements in the 2.3–4.3 μm wavelength range [1]. The instrumental resolving power λ/Δλ reaches ~30 000, while the altitude resolution is ~1 km. ACS-MIR began regular science operations in April 2018 on board the ExoMars Trace Gas Orbiter (TGO). Each occultation session covers a spectral interval with one or a few CO<sub>2</sub> absorption bands appropriate for the atmospheric density and temperature retrievals.</p><p>In this paper, we present results from data analysis in the 2.65-2.7 μm spectral range hosting strong CO<sub>2</sub> absorption bands detectable up to 180 km. It provides us with unprecedented capability to profile CO<sub>2</sub> from 20 to 180 km, covering the troposphere, the mesosphere and the thermosphere of Mars. The homopause is found around ~130 km and CO<sub>2</sub> mixing ratio decreases from 96% to 20-40% at 180 km due to photolysis and molecular diffusion. A multiple iteration scheme was applied to retrieve CO<sub>2</sub> density and temperature from the rotational absorption lines, while pressure was estimated assuming hydrostatic equilibrium. The vertical profiles coincide well with the simultaneous occultations performed below 100 km by the near-infrared channel ACS-NIR [2]. At the moment, our MIR channel dataset is made of >100 profiles encompassing the second half of MY34 and the beginning of MY35 in both martian hemispheres. The retrievals of density/temperature profiles in IKI are funded by the RSF grant #20-42-09035.</p><p>REFERENCES</p><p>[1] Korablev O. et al., 2018. The Atmospheric Chemistry Suite (ACS) of three spectrometers for the ExoMars 2016 Trace Gas Orbiter. Space Sci. Rev., 214:7. DOI 10.1007/s11214-017-0437-6.</p><p>[2] Fedorova A. et al., 2020. Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season. Science, eaay9522. DOI: 10.1126/science.aay9522.</p>

First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers

2018 ◽  
Author(s):  
Adrian Cernescu ◽  
Michał Szuwarzyński ◽  
Urszula Kwolek ◽  
Karol Wolski ◽  
Paweł Wydro ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Absorption Band ◽  
Spectral Region ◽  
Near Field ◽  
Phospholipid Bilayers ◽  
Model Systems ◽  
Absorption Bands ◽  
Protein Complement ◽  
20 Nm

<div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div>

Magnetic dipole and electric quadrupole rotational structures and chirality inRh105

2004 ◽  
Vol 69 (2) ◽  
Author(s):  
J. A. Alcántara-Núñez ◽  
J. R. B. Oliveira ◽  
E. W. Cybulska ◽  
N. H. Medina ◽  
M. N. Rao ◽  
...  
Keyword(s):  
Magnetic Dipole ◽  
Electric Quadrupole

Intercomparison of Cloud Products based on S5P/TROPOMI Level 1b Data Version 1 and the updated Version 2

2021 ◽  
Author(s):  
Miriam Latsch ◽  
Andreas Richter ◽  
John P. Burrows ◽  
Thomas Wagner ◽  
Holger Sihler ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Recognition Algorithm ◽  
Cloud Fraction ◽  
Trace Gas ◽  
Oxygen Absorption ◽  
Data Sets ◽  
Absorption Bands ◽  
Data Set ◽  
Trace Species ◽  
Retrieval Scheme

&lt;p&gt;The first European Sentinel satellite for monitoring the composition of the Earth&amp;#8217;s atmosphere, the Sentinel 5 Precursor (S5p), carries the TROPOspheric Monitoring Instrument (TROPOMI) to map trace species of the global atmosphere at high spatial resolution. Retrievals of tropospheric trace gas columns from satellite measurements are strongly influenced by clouds. Thus, cloud retrieval algorithms were developed and implemented in the trace gas processing chain to consider this impact.&lt;/p&gt;&lt;p&gt;In this study, different cloud products available for NO&lt;sub&gt;2&lt;/sub&gt; retrievals based on the TROPOMI level 1b data version 1 and an updated TROPOMI level 1b test data set of version 2 (Diagnostic Data Set 2B, DDS2B) are analyzed. The data sets include a) the TROPOMI level 2 OCRA/ROCINN (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks) cloud products CRB (cloud as reflecting boundaries) and CAL (clouds as layers), b) the FRESCO (Fast Retrieval Scheme for Clouds from Oxygen absorption bands) cloud product,&amp;#160; c) the cloud fraction from the NO&lt;sub&gt;2&lt;/sub&gt; fitting window, d) the VIIRS (Visible Infrared Imaging Radiometer Suite) cloud product, and e) the MICRU (Mainz Iterative Cloud Retrieval Utilities) cloud fraction. The cloud products are compared with regard to cloud fraction, cloud height, cloud albedo/optical thickness, flagging and quality indicators in all 4 seasons. In particular, the differences of the cloud products under difficult situations such as snow or ice cover and sun glint are investigated.&lt;/p&gt;&lt;p&gt;We present results of a statistical analysis on a limited data set comparing cloud products from the current and the upcoming lv2 data versions and their approaches. The aim of this study is to better understand TROPOMI cloud products and their quantitative impacts on trace gas retrievals.&lt;/p&gt;

scholarly journals Case studies of the impact of orbital sampling on stratospheric trend detection and derivation of tropical vertical velocities: solar occultation vs. limb emission sounding

2016 ◽  
Vol 16 (18) ◽  
pp. 11521-11534 ◽  
Author(s):  
Luis F. Millán ◽  
Nathaniel J. Livesey ◽  
Michelle L. Santee ◽  
Jessica L. Neu ◽  
Gloria L. Manney ◽  
...  
Keyword(s):  
Case Studies ◽  
Atmospheric Chemistry ◽  
Stratospheric Ozone ◽  
Sampling Bias ◽  
Nonuniform Sampling ◽  
Trend Detection ◽  
Trace Gas ◽  
Uniform Sampling ◽  
Solar Occultation ◽  
The Impact

Abstract. This study investigates the representativeness of two types of orbital sampling applied to stratospheric temperature and trace gas fields. Model fields are sampled using real sampling patterns from the Aura Microwave Limb Sounder (MLS), the HALogen Occultation Experiment (HALOE) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). The MLS sampling acts as a proxy for a dense uniform sampling pattern typical of limb emission sounders, while HALOE and ACE-FTS represent coarse nonuniform sampling patterns characteristic of solar occultation instruments. First, this study revisits the impact of sampling patterns in terms of the sampling bias, as previous studies have done. Then, it quantifies the impact of different sampling patterns on the estimation of trends and their associated detectability. In general, we find that coarse nonuniform sampling patterns may introduce non-negligible errors in the inferred magnitude of temperature and trace gas trends and necessitate considerably longer records for their definitive detection. Lastly, we explore the impact of these sampling patterns on tropical vertical velocities derived from stratospheric water vapor measurements. We find that coarse nonuniform sampling may lead to a biased depiction of the tropical vertical velocities and, hence, to a biased estimation of the impact of the mechanisms that modulate these velocities. These case studies suggest that dense uniform sampling such as that available from limb emission sounders provides much greater fidelity in detecting signals of stratospheric change (for example, fingerprints of greenhouse gas warming and stratospheric ozone recovery) than coarse nonuniform sampling such as that of solar occultation instruments.

scholarly journals Dynamics and composition of the Asian summer monsoon anticyclone

2017 ◽  
Author(s):  
Klaus-Dirk Gottschaldt ◽  
Hans Schlager ◽  
Robert Baumann ◽  
Duy S. Cai ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Atmospheric Chemistry ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Lower Troposphere ◽  
Equatorial Region ◽  
Ozone Production ◽  
Trace Gas ◽  
Asian Summer ◽  
Southern Fringe

Abstract. This study places HALO research aircraft observations in the upper-tropospheric Asian summer monsoon anticyclone (ASMA) obtained during the Earth System Model Validation (ESMVal) campaign in September 2012 into the context of regional, intra-annual variability by hindcasts with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The simulations demonstrate that tropospheric trace gas profiles in the monsoon season are distinct from the rest of the year. Air uplifted from the lower troposphere to the tropopause layer dominates the eastern part of the ASMA’s interior, while the western part is characterised by subsidence down to the mid-troposphere. Soluble compounds are being washed out when uplifted by convection in the eastern part, where lightning simultaneously replenishes reactive nitrogen in the upper troposphere. Net photochemical ozone production is significantly enhanced in the ASMA, contrasted by an ozone depleting regime in the mid-troposphere and more neutral conditions in autumn and winter. An analysis of multiple monsoon seasons in the simulation shows that stratospherically influenced tropopause layer air is regularly entrained at the eastern ASMA flank, and then transported in the southern fringe around the interior region. Observed and simulated tracer-tracer relations reflect photochemical O3 production, as well as in-mixing from the lower troposphere and the tropopause layer. The simulation additionally shows entrainment of clean air from the equatorial region by northerly winds at the western ASMA flank. Although the in situ measurements were performed towards the end of summer, the main ingredients needed for their interpretation are present throughout the monsoon season. A transition between two dynamical modes of the ASMA took place during the HALO ESMVal campaign. Transport barriers of the original anticyclone are overcome effectively when it splits up. Air from the fringe is stirred into the interiors of the new anticyclones and vice versa. Instabilities of this and other types occur quite frequently. Our study emphasises their paramountcy for the trace gas composition of the ASMA and its outflow into regions around the world.

ELECTROWEAK BOSON SELF-COUPLINGS AND THE SCALE OF COMPOSITENESS

1988 ◽  
Vol 03 (01) ◽  
pp. 225-242 ◽  
Author(s):  
J.A. GRIFOLS ◽  
S. PERIS ◽  
J. SOLÅ
Keyword(s):  
Magnetic Dipole ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Weak Boson ◽  
Experimental Rate ◽  
Experimental Constraint ◽  
Electroweak Boson

The experimental constraint on [Formula: see text] and the experimental rate of the process KL→μμ are used to bound hypothetical nonstandard self-interactions of the electroweak bosons. In particular, we give bounds on anomalous magnetic dipole and electric quadrupole moments of the charged weak boson.

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