The far-infrared spectrum of hydrogen sulfide. The (000) rotational constants of , , and

1983 ◽  
Vol 61 (10) ◽  
pp. 1462-1473 ◽  
Author(s):  
J.-M. Flaud ◽  
C. Camy-Peyret ◽  
J. W. C. Johns
Keyword(s):  
Hydrogen Sulfide ◽  
Signal To Noise Ratio ◽  
Far Infrared ◽  
Infrared Region ◽  
Rotational Constants ◽  
Pure Rotation ◽  
Isotopic Species ◽  
Least Squares Fit ◽  
Rotational Transitions ◽  
Good Signal

The pure rotation spectrum of hydrogen sulfide has been recorded between 50 and 320 cm−1 with a Fourier transform spectrometer at an apodized resolution of 0.005 cm−1. This high resolution and a good signal-to-noise ratio lead to a significant improvement in the accuracy of the wavenumbers of the rotational transitions of the three isotopic species [Formula: see text], [Formula: see text], and [Formula: see text] that were observed in natural abundance. These rotational transitions, together with the available microwave data, have been included in a least squares fit leading to the determination of precise rotational constants for each isotopic species. Finally, these constants have been used to calculate precisely the absorption of natural hydrogen sulfide in the far-infrared region of the spectrum.

Pure Rotation Spectrum of NNO in the Far Infrared Region

1990 ◽  
Vol 45 (6) ◽  
pp. 837-838 ◽  
Author(s):  
Koichi M. T. Yamada
Keyword(s):  
Vibrational State ◽  
Far Infrared ◽  
Infrared Region ◽  
Submillimeter Wave ◽  
Fourier Transform Spectrometer ◽  
Rotational Spectrum ◽  
Precise Data ◽  
Pure Rotation ◽  
Least Squares Fit ◽  
Rotation Spectrum

AbstractThe pure rotational spectrum of NNO has been observed as an impurity in the NO spectrum which has been recorded with a high resolution Fourier transform spectrometer. The observed high-J transitions in the ground vibrational state were analyzed by a least-squares fit together with the available millimeter and submillimeter wave data. It has been proved that the highly precise data of Maki et al. [3] can be used as a wavenumber standard for the far infrared.

Identification of a vibrationally excited level in methyl formate through microwave and far-infrared spectroscopy

2020 ◽  
Vol 98 (6) ◽  
pp. 551-554
Author(s):  
Kaori Kobayashi ◽  
Yusuke Sakai ◽  
Masaharu Fujitake ◽  
Dennis W. Tokaryk ◽  
Brant E. Billinghurst ◽  
...  
Keyword(s):  
Excited States ◽  
Ground State ◽  
Methyl Formate ◽  
Excited Level ◽  
Far Infrared ◽  
Infrared Region ◽  
Far Infrared Spectroscopy ◽  
Interstellar Molecule ◽  
Vibrationally Excited ◽  
Rotational Transitions

Methyl formate (HCOOCH3) is an important interstellar molecule. More than 1000 rotational transitions including those from the ground state, torsionally excited states, and of its isotopologues have been observed towards several astrophysical sources. The laboratory spectra of methyl formate in the microwave spectral region contain many unassigned transitions and many of them are likely to be due to rotational transitions in the low-lying excited states. We report the laboratory identification of new rotational transitions in the COC deformation (ν12) excited state. The identification was made possible by combining the microwave data with rotation–vibration spectra taken in the far-infrared region at the Canadian Light Source synchrotron.

The Molecular Structures of HNC and HCN Derived from the Eight Stable Isotopic Species

1976 ◽  
Vol 31 (11) ◽  
pp. 1394-1397 ◽  
Author(s):  
E. F. Pearson ◽  
R. A. Creswell ◽  
M. Winnewisser ◽  
G. Winnewisser
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Vibrational State ◽  
Molecular Structures ◽  
Rotational Constants ◽  
Ground Vibrational State ◽  
Isotopic Species ◽  
Stable Isotopic ◽  
Rotational Transitions

Abstract Ground vibrational state rotational transitions have been measured for the following isotopic species of HNC: H15NC, H15N13C, DN13C, D15NC and D15N13C. Similar transitions have also been measured for H13C15N and D13C15N. These measurements complete the set of rotational constants for the eight stable isotopic species of the two molecules. Molecular structures are calculated from these data in several ways and are compared with the results of recent ab initio calculations.

scholarly journals IRC +10216 as a spectroscopic laboratory: improved rotational constants for SiC2, its isotopologues, and Si2C

2018 ◽  
Vol 618 ◽  
pp. A4 ◽  
Author(s):  
J. Cernicharo ◽  
M. Guélin ◽  
M. Agúndez ◽  
J. R. Pardo ◽  
S. Massalkhi ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Molecular Species ◽  
Signal To Noise Ratio ◽  
Laboratory Data ◽  
High Spectral Resolution ◽  
Circumstellar Envelope ◽  
Centrifugal Distortion ◽  
Rotational Constants ◽  
Good Signal ◽  
Centrifugal Distortion Constants

This work presents a detailed analysis of the laboratory and astrophysical spectral data available for 28SiC2, 29SiC2, 30SiC2, Si13CC, and Si2C. New data on the rotational lines of these species between 70 and 350 GHz have been obtained with high spectral resolution (195 kHz) with the IRAM 30 m telescope in the direction of the circumstellar envelope IRC +10216. Frequency measurements can reach an accuracy of 50 kHz for features observed with a good signal to noise ratio. From the observed astrophysical lines and the available laboratory data new rotational and centrifugal distortion constants have been derived for all the isotopologues of SiC2, allowing us to predict their spectrum with an estimated accuracy better than 50 kHz below 500 GHz and around 50–100 kHz for the strong lines above 500 GHz. Improved rotational and centrifugal distortion constants have also been obtained for disilicon carbide, Si2C. This work shows that observations of IRC +10216 taken with the IRAM 30 m telescope, with a spectral resolution of 195 kHz, can be used for any molecular species detected in this source to derive, or improve, its rotational constants. Hence, IRC +10216 in addition to be one the richest sources in molecular species in the sky, can also be used as a spectroscopy laboratory in the millimetre and submillimetre domains.

Background subtraction in STEM energy-loss mapping

1984 ◽  
Vol 42 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
K.E. Gorlen ◽  
C.R. Swyt
Keyword(s):  
Energy Loss ◽  
Signal To Noise Ratio ◽  
Statistical Error ◽  
Scanning Transmission Electron Microscope ◽  
Reference Image ◽  
Inverse Power Law ◽  
Transmission Electron ◽  
Least Squares Fit ◽  
Scanning Transmission ◽  
Single Number

The determination of elemental distributions by electron energy loss spectroscopy necessitates removal of the non-characteristic spectral background from a core-edge at each point in the image. In the scanning transmission electron microscope this is made possible by computer controlled data acquisition. Data may be processed by fitting the pre-edge counts, at two or more channels, to an inverse power law, AE-r, where A and r are parameters and E is energy loss. Processing may be performed in real-time so a single number is saved at each pixel. Detailed analysis, shows that the largest contribution to noise comes from statistical error in the least squares fit to the background. If the background shape remains constant over the entire image, the signal-to-noise ratio can be improved by fitting only one parameter. Such an assumption is generally implicit in subtraction of the “reference image” in energy selected micrographs recorded in the CTEM with a Castaing-Henry spectrometer.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

Hagen-Rubens relation beyond far-infrared region

2010 ◽  
Vol 90 (4) ◽  
pp. 44004 ◽  
Author(s):  
F. E. M. Silveira ◽  
S. M. Kurcbart
Keyword(s):  
Far Infrared ◽  
Infrared Region
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