•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.
Molecular opacities for exoplanets Bernath, Peter F.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
04/2014, Letnik:
372, Številka:
2014
Journal Article
Recenzirano
Odprti dostop
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.
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.
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.
New rotational line strengths for the C2 Swan system (dΠg3–aΠu3) have been calculated for vibrational bands with v′=0–10 and v″=0–9, and J values up to J=34–96, using previous observations in 33 ...vibrational bands. Line positions from several sources were combined with the results from recent deperturbation studies of the v′=4 and v′=6 levels, and a weighted global least squares fit was performed. The updated molecular constants are reported. The line strengths are based on a recent ab initio calculation of the transition dipole moment function. A line list has been made available, including observed and calculated line positions, Einstein A coefficients and oscillator strengths (f-values). The line list will be useful for astronomers, combustion scientists and materials scientists who utilize C2 Swan spectra. Einstein A coefficients and f-values were also calculated for the vibrational bands of the Swan system.
► Line positions from several previous studies of the C2 Swan system are combined. ► Molecular constants have been recalculated including v′=4 and v′=6 perturbations. ► Rotational line intensities are calculated as Einstein A and f-values. ► Vibrational band Einstein Av′v″ and fv′v″ values are calculated. ► We give a line list up to v′=10, v″=9 with intensities for obs. and calc. lines.
•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).
High-resolution infrared spectra of the symmetric top isobutane CH(CH3)3 were assigned with the help of ab initio calculations. The strong parallel band ν5(a1) with an origin at 1396.54741(76) cm–1 ...and the ν4(a1) mode, the CH2 scissors, at 1478.20363(41) cm–1 were rotationally analyzed. The bands in the C–H stretching region were assigned with the help of an anharmonic calculation and a local mode analysis.
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