•Review of requirements and calculations for line lists for astronomical and atmospheric applications.•MOLLIST (Molecular Line Lists, Intensities and Spectra) data compilation is presented.•Units ...used in line lists and their conversion are discussed.
The simulation of astronomical spectra of cool stars, brown dwarfs and exoplanets requires high resolution line lists and absorption cross sections of many molecules. Similar data sets are needed for the Earth’s atmosphere and other planets in our solar system. The requirements for line lists are reviewed and methods used to create them are discussed. Equations to convert between different units are provided. The MoLLIST (Molecular Line Lists, Intensities and Spectra) data compilation is presented and used as an example.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cool red giant stars exhibit absorption bands of calcium monochloride (CaCl) in the optical region. In this work, the bands of CaCl corresponding to the A2Π − X2Σ+ transition with v′≤ 4 and v″ ≤ 4, ...and B2Σ+ − X2Σ+ transition with v′≤ 2 and v″ ≤ 2 are rotationally analyzed with PGOPHER, a multipurpose program for simulating and fitting molecular spectra. All bands were analyzed using high-resolution absorption spectra collected at the National Solar Observatory in 1985, calibrated with atomic lines from a high-resolution emission spectrum obtained in a separate hollow cathode experiment. The results are compared with previous laser-induced fluorescence measurements. Overall, the accuracy of spectroscopic constants for the A2Π and B2Σ+ states is improved. Scaled transition dipole moment calculations were used to obtain line strengths. Line lists are provided with Einstein A coefficients and oscillator strengths, which can be used to determine CaCl stellar abundances. Additionally, isotope splittings allowed us to estimate band origins for the 40Ca37Cl isotopologue based on band-head positions.
Molecular opacities for exoplanets Bernath, Peter F.
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
04/2014, Volume:
372, Issue:
2014
Journal Article
Peer reviewed
Open access
Spectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanets are reviewed based on existing measurements and model ...predictions for hot Jupiters and super-Earths. Molecular opacities needed to simulate astronomical observations can be obtained from laboratory measurements, ab initio calculations or a combination of the two approaches. This discussion article focuses mainly on laboratory measurements of hot molecules as needed for exoplanet spectroscopy.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Abstract
The ZrO
B
1
Π–
X
1
Σ
+
,
B
1
Π–
A
1
Δ, and
C
1
Σ
+
–
X
1
Σ
+
band systems are important opacity sources in the near-infrared and optical spectra of S-type stars. A total of 21 rovibronic ...bands with
v
″ ≤ 7 and
v
′
≤
5
were observed and fit for the
B
1
Π–
X
1
Σ
+
transition, five bands for the
90
ZrO
B
1
Π–
A
1
Δ transition and one band for the
90
ZrO
C
1
Σ
+
–
X
1
Σ
+
transition. All band systems were analyzed using high-temperature, high-resolution emission spectra collected at the National Solar Observatory (Kitt Peak). A modern spectroscopic analysis was performed using the PGOPHER program to provide updated spectroscopic constants. In general, we improve the accuracy of the line positions reported in the literature and slightly extend the vibrational analysis. Equilibrium molecular constants were then derived and combined with new ab initio calculations of transition dipole moment functions to produce line lists with line strengths.
The ZrO B1Π—X1Σ+ transition is an important opacity source in the near-infrared and optical spectrum of S-type stars. The 0–0, 0–1, 0–2, 1–0, 1–2, 1–3, 2–0, 2–1, 2–3, 2–4, 3–1, 3–4, and 4–2 bands of ...the 90Zr16O B1Π—X1Σ+ transition are reanalyzed using a high-temperature (2390 K) high-resolution (0.04 cm−1) emission spectrum collected at the National Solar Observatory (Kitt Peak). A modern spectroscopic analysis was performed using the PGOPHER program to provide updated spectroscopic constants and to produce a high-precision line list with line strengths based on an ab initio calculation of the transition dipole moment.
SCISAT-1, also known as the Atmospheric Chemistry Experiment, is a satellite mission for remote sensing of the Earth's atmosphere, launched on 12 August 2003. The primary instrument on the satellite ...is a 0.02 cm(-1) resolution Fourier-transform spectrometer operating in the mid-IR (750-4400 cm(-1)). We describe the approach developed for the retrieval of atmospheric temperature and pressure from the troposphere to the lower thermosphere as well as the strategy for the retrievals of volume-mixing ratio profiles of atmospheric species.
Spectra of hot methane were recorded using a tube furnace and a high-resolution Fourier transform spectrometer. We obtained experimental absorption spectra in the 1.85-1.11 m near-infrared region at ...eight temperatures ranging from 295 K up to 1000 K. We have converted these into an atlas of absorption cross sections at each temperature for the methane tetradecad, icosad and triacontad polyads, excluding some spectral intervals either strongly contaminated by water or due to baseline fringes. On the theoretical side, the spectra were simulated from the ab initio-based Reims-Tomsk TheoReTS line list for the same experimental conditions. This line list has been constructed by global variational calculations from potential energy and dipole moment surfaces followed by empirical line position corrections deduced from previously published analyses. The comparisons showed very good overall agreement between observations and theory at high spectral resolution for the tetradecad and icosad and at medium or low resolution above this range. A full set of the theoretical absorption cross sections is also included. Detailed temperature dependence of the methane absorption enables the efficient method of remotely probing the temperature of distant astronomical objects based on a comparison of relative signals in carefully selected spectral intervals. This first combined experimental and theoretical easy-to-use cross-section library in the near-infrared should be of major interest for the interpretation of current and future astronomical observations up to a resolving power of 100,000-300,000 in the range 6400-7600 cm−1 and a resolving power of 5000-10,000 in the higher wavenumber range up to 9000 cm−1.
High-resolution infrared absorption spectra of cyclohexane have been recorded from 1100 to 4000 cm–1 at room temperature and 241 K. Cyclohexane is an oblate symmetric top with D 3d symmetry. A ...rotational analysis was obtained for the ν27 (eu) and ν14 (a2u) CH2 scissor modes at 1452.9 and 1456.4 cm–1, respectively. Several combination modes were also assigned and rotationally analyzed. The C–H stretching modes are perturbed by overtone and combination modes of the CH2 scissor vibrations, and an anharmonic local mode calculation was needed to interpret the spectra. The four main strong allowed C–H stretching modes appear as two a2u eu pairs near at 2862 and 2933 cm–1. The Fermi-resonance local mode model coupling terms give physical insight into the effects that organize the cyclohexane vibrational energy levels. The unstrained cyclohexane molecule is a useful paradigm for six-membered rings in larger chemical and biological systems.
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Trends in atmospheric HFC-23 (CHF3) and HFC-134a abundances Fernando, Anton M.; Bernath, Peter F.; Boone, Christopher D.
Journal of Quantitative Spectroscopy & Radiative Transfer/Journal of quantitative spectroscopy & radiative transfer,
November 2019, 2019-11-00, Volume:
238
Journal Article
Peer reviewed
Open access
•Linear trends of atmospheric HFC-134a and CHF3 from ACE-FTS data.•Description of HFC-134a and CHF3 retrievals.•Comparison with Advanced Global Atmospheric Gases Experiment (AGAGE) data.
The Montreal ...Protocol banned the production of major ozone depleting substances such as chlorofluorocarbons (CFCs) to protect the Earth’s ozone layer. The resulting increased production and emissions of CFC-replacement hydrofluorocarbons (HFCs) has caused a dramatic increase in their atmospheric abundances. Although these HFCs do not contribute directly to the depletion of the ozone layer because they contain no chlorine, they are powerful greenhouse gases with large global warming potentials. In January 2019, the Kigali Amendment to the Montreal Protocol came into force to phase out long-lived HFCs. The two most abundant HFCs in the atmosphere, HFC-134a (CF3CH2F) and HFC-23 (CHF3), are measured from orbit by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). These measurements will be useful for monitoring the Kigali Amendment to the Montreal Protocol. Analysis of the ACE-FTS measurements provides near-global distributions and confirms the rapid increase in HFC-134a (4.9 ± 0.1 ppt per year) and HFC-23 (0.75 ± 0.02 ppt per year) volume mixing ratios (VMRs).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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