Measured Optical Absorption Cross Sections of TiO

A laboratory emission spectrum of TiO in the visible and near-infrared regions (476–1176 nm) has been calibrated and corrected. High-resolution experimental absorption cross sections for TiO with natural isotopic abundance are provided at a temperature of about 2300 K. These cross sections have been compared with those derived from the ExoMol line list. The experimental cross sections can be used directly as a template for cross correlation TiO detection in hot Jupiter exoplanets

Cyclohexane Vibrations: High Resolution Spectra And Anharmonic Local Mode Calculations

High resolution infrared absorption spectra of cyclohexane (C$_6$H$_{12}$) 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 $\nu_{27}$ (e$_{\rm{u}}$) and $\nu_{14}$ (a$_{\rm{2u}}$) CH$_2$ scissor modes at 1452.9 cm$^{-1}$ 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 CH$_2$ scissor vibrations, and an anharmonic local mode calculation was needed to interpret the spectra. The 4 main strong allowed C-H stretching modes appear as two e$_{\rm{u}}$ a$_{\rm{2u}}$ pairs near at 2862 cm$^{-1}$ 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

Empirical line lists and absorption cross sections for methane at high temperature

Hot methane is found in many "cool" sub-stellar astronomical sources including brown dwarfs and exoplanets, as well as in combustion environments on Earth. We report on the first high-resolution laboratory absorption spectra of hot methane at temperatures up to 1200 K. Our observations are compared to the latest theoretical spectral predictions and recent brown dwarf spectra. The expectation that millions of weak absorption lines combine to form a continuum, not seen at room temperature, is confirmed. Our high-resolution transmittance spectra account for both the emission and absorption of methane at elevated temperatures. From these spectra, we obtain an empirical line list and continuum that is able to account for the absorption of methane in high temperature environments at both high and low resolution. Great advances have recently been made in the theoretical prediction of hot methane, and our experimental measurements highlight the progress made and the problems that still remain.Comment: 9 pages, 5 figures and 3 tables. For associated online data see http://dx.doi.org/10.1088/0004-637X/813/1/1

Spectroscopic Constants and Line Positions for TiO Singlet States

consistent set of spectroscopic constants for the a1Δ,d1Σ+,b1Π,c1Φ, and f1Δ states of 48Ti16O has been determined from analysis of the b1Π–a1Δ,b1Π–d1Σ+,c1Φ–a1Δ, and f1Δ–a1Δ systems. Three Fourier transform emission spectra have been used for the analysis. New bands of the b1Π–a1Δ and c1Φ–a1Δ systems have been fitted. The first analysis of the c1Φ–a1Δ system using Fourier transform spectra is also provided. Extensive and improved line positions are measured. TiO is prominent in the spectra of oxygen-rich cool stellar objects and may be present in hot-Jupiter exoplanet atmospheres

Fourier Transform Spectroscopy of the A3Π–X3Σ− Transition of OH+

The OH+ ion is of critical importance to the chemistry in the interstellar medium and is a prerequisite for the generation of more complex chemical species. Submillimeter and ultraviolet observations rely on high quality laboratory spectra. Recent measurements of the fundamental vibrational band and previously unanalyzed Fourier transform spectra of the near-ultraviolet A3Π-X 3Σ- electronic spectrum, acquired at the National Solar Observatory at Kitt Peak in 1989, provide an excellent opportunity to perform a global fit of the available data. These new optical data are approximately four times more precise as compared to the previous values. The fit to the new data provides updated molecular constants, which are necessary to predict the OH+ transition frequencies accurately to support future observations. These new constants are the first published using the modern effective Hamiltonian for a linear molecule. These new molecular constants allow for easy simulation of transition frequencies and spectra using the PGOPHER program. The new constants improve simulations of higher J-value infrared transitions, and represent an improvement of an order of magnitude for some constants pertaining to the optical transitions. © 2017. The American Astronomical Society

Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra

New red and violet system line lists for the CN isotopologues 13C14N and 12C15N have been generated. These new transition data are combined with those previously derived for 12C14N, and applied to the determination of CNO abundances in the solar photosphere and in four red giant stars: Arcturus, the bright very low-metallicity star HD 122563, and carbon-enhanced metal-poor stars HD 196944 and HD 201626. When lines of both red and violet system lines are detectable in a star, their derived N abundances are in good agreement. The mean N abundances determined in this work generally are also in accord with published values.Comment: ApJS, in press, 37 pages, 7 figures, 3 table