Уширение и сдвиг линий основной колебательно-вращательной полосы молекул фтористого водорода молекулами SF-=SUB=-6-=/SUB=- и H-=SUB=-2-=/SUB=-

Foreign gas broadening and shift of the vibration-rotation lines in the fundamental band of hydrogen fluoride have been investigated. Using mathematical modeling of measuring the absorption of radiation of an electric discharge HF laser, the possibility of correct calculations of both broadening and shift of HF lines by foreign gases were determined. Measurements for two foreign gases (Ar and N2 for which there are literature data) were made in order to test this approach. The obtained results have been well matched with existing literature data. After that, measurements were carried out on two transitions P(7) and P(8) for SF6 (for which neither broadening nor the shift are known) and for H2 (only broadening is known for overtone band). The obtained results were compared with scarce literature data.

New Temperature and Metallicity Scale of Cool Giants from K-band Spectra

We present here quantitative diagnostic tools for cool giants that employ low-resolution near-infrared spectroscopy in the K-band for stellar population studies. In this study, a total of 260 cool giants (177 stars observed with X-shooter and 83 stars observed with NIFS) are used covering a wider metallicity range than in earlier works. We measure equivalent widths of some of the selected important K-band spectral features like Na I, Fe I and 12CO after degrading the spectral resolution (R∼ 1200) to investigate the spectral behavior with fundamental parameters (e.g. effective temperature and metallicity). We derive empirical relations to measure effective temperature using the 12CO first-overtone band at 2.29 μm and 2.32 μm and show a detailed quantitative metallicity dependence of these correlations. We find that the empirical relations based on solar-neighborhood stars can incorporate large uncertainty in evaluating Teff for metal-poor or metal-rich stars. Furthermore, we explore all the spectral lines to establish the empirical relation with metallicity and find that the quadratic fit of the combination of Na I and 12CO at 2.29 μm lines yields a reliable empirical relation at [Fe/H] ≤ –0.4 dex, while a linear fit of any line offers a good metallicity scale for stars having [Fe/H] ≥ 0.0 dex.

Vertical wind profiling from troposphere to the lower mesosphere based on high resolution heterodyne near-infrared spectroradiometry

We propose a new technique of remote wind measurements based on Doppler analysis of a CO2 absorption line in the 1.605 μm overtone band measured in the direct Sun observation geometry. Heterodyne spectroradiometric measurements of the solar radiation passed through the atmosphere provides an unprecedented spectral resolution up to λ/δλ ~ 107–108 with a signal-to-noise ratio more than 100. The shape of the individual rotational line profile provides unambiguous relationship between offset from the line centre and altitude where a respective part of the line profile is formed. Therefore, an inverse problem may be posed in order to retrieve vertical distribution of wind, with retrievals vertical resolution compromised by a spectral resolution and signal-to-noise ratio of the measurements. A close coincidence between measured and synthetic absorption line is reached, with retrieved wind profile between the surface and 50 km being in a good agreement with reanalysis models. This method may pose an alternative to widely employed lidar and radar techniques.

Search for H3+ isotopologues toward CRL 2136 IRS 1

Context. Deuterated interstellar molecules frequently have abundances relative to their main isotopologues much higher than the overall elemental D-to-H ratio in the cold dense interstellar medium. H3+ and its isotopologues play a key role in the deuterium fractionation; however, the abundances of these isotopologues have not been measured empirically with respect to H3+ to date. Aims. Our aim was to constrain the relative abundances of H2D+ and D3+ in the cold outer envelope of the hot core CRL 2136 IRS 1. Methods. We carried out three observations targeting H3+ and its isotopologues using the spectrographs CRIRES at the VLT, iSHELL at IRTF, and EXES on board SOFIA. In addition, the CO overtone band at 2.3 μm was observed by iSHELL to characterize the gas on the line of sight. Results. The H3+ ion was detected toward CRL 2136 IRS 1 as in previous observations. Spectroscopy of lines of H2D+ and D3+ resulted in non-detections. The 3σ upper limits of N(H2D+)/N(H3+) and N(D3+)/N(H3+) are 0.24 and 0.13, respectively. The population diagram for CO is reproduced by two components of warm gas with the temperatures 58 and 530 K, assuming a local thermodynamic equilibrium (LTE) distribution of the rotational levels. Cold gas (<20 K) makes only a minor contribution to the CO molecular column toward CRL 2136 IRS 1. Conclusions. The critical conditions for deuterium fractionation in a dense cloud are low temperature and CO depletion. Given the revised cloud properties, it is no surprise that H3+ isotopologues are not detected toward CRL 2136 IRS 1. The result is consistent with our current understanding of how deuterium fractionation proceeds.

Изотопные эффекты в спектрах комплексов с водородной связью. Экспериментальное и теоретическое изучение спектра ИК поглощения комплекса (-=SUP=-12-=/SUP=-CH-=SUB=-3-=/SUB=-)-=SUB=-2-=/SUB=--=SUP=-13-=/SUP=-CO...НF

IR absorption spectra of mixtures (^12CH_3) $$_{2}^{{13}}$$ CO/HF and free (^12CH_3) $$_{2}^{{13}}$$ CO molecules are recorded in the region of 4000−800 cm^−1 with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution of 0.05 cm^−1. Absorption bands of the (^12CH_3) $$_{2}^{{13}}$$ CO…HF complex are obtained by subtracting the absorption bands of free HF and acetone molecules and absorption lines of atmospheric water from the experimental spectrum of mixtures. Spectral characteristics of the 2ν(^13C=O) overtone band of free acetone were also recorded. Comparison of the spectral data obtained with the analogous data measured earlier for the (^12CH_3) $$_{2}^{{12}}$$ CO…HF complex shows changes in the absorption spectra of complexes caused by ^12C → ^13C isotopic substitution. The frequencies and intensities for absorption bands of both complexes are calculated using the perturbation theory and methods MP2/6-311++G(2d,2p) and MP2/6-311++G(3df,3pd) with allowance for the error of superposition of basis functions of the monomers. The calculated results are in good agreement with the experimental data and are used to interpret the observed spectra. The influence of anharmonic effects on the frequencies and intensities of the strongest ν(H–F) and ν(^13C=O) bands is examined with the help of variational calculations. It is shown that, unlike the (^12CH_3) $$_{2}^{{12}}$$ CO…HF complex, the 2ν(^13C=O)/ν(H–F) resonance is virtually absent in the (^12CH_3) $$_{2}^{{13}}$$ CO…HF complex.