Millimeter‐Wave and Vibrational State Assignments for the Rotational Spectrum of Glycolaldehyde (original) (raw)
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Millimeter and submillimeter wave spectra of 13 C-glycolaldehydes
Astronomy & Astrophysics, 2013
Context. Glycolaldehyde (CH 2 OHCHO) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. Astronomical surveys of interstellar molecules, such as those available with the very sensitive ALMA telescope, require preliminary laboratory investigations of the microwave and submillimeter-wave spectra of molecular species including new isotopologs -to identify these in the interstellar media. Aims. To achieve the detection of the 13 C isotopologs of glycolaldehyde in the interstellar medium, their rotational spectra in the millimeter and submillimeter-wave regions were studied.
The pure rotational spectrum of glycolaldehyde isotopologues observed in natural abundance
Journal of Molecular Spectroscopy, 2013
The pure rotational spectrum of glycolaldehyde has been recorded from 6.5-20 GHz and 25-40 GHz in two pulsed-jet chirped pulse Fourier transform microwave spectrometers. The high phase stability of the spectrometers enables deep signal integration, allowing transitions from the 13 C-substituted, 18 Osubstituted, and deuterium-substituted isotopologues to be observed in natural abundance. Transitions from HCOCH 2 18 OH are reported for the first time. Additional transitions from the 13 C-substituted, deuterium-substituted, and HC 18 OCH 2 OH isotopologues, as well as previously unobserved weak lines from the main isotopologue, have been observed. Transitions from all isotopologues are used with previously reported transitions to refine the spectroscopic parameters for each isotopologue. A Kraitchman analysis was performed using the experimental rotational constants to determine the molecular structure of glycolaldehyde.
The submillimeter spectrum of deuterated glycolaldehydes
Astronomy & Astrophysics, 2012
Context. Glycolaldehyde, a sugar-related interstellar prebiotic molecule, has recently been detected in two star-forming regions, Sgr B2(N) and G31.41+0.31. The detection of this new species increased the list of complex organic molecules detected in the interstellar medium (ISM) and adds another level to the chemical complexity present in space. Besides, this kind of organic molecule is important because it is directly linked to the origin of life. For many years, astronomers have been struggling to understand the origin of this high chemical complexity in the ISM. The study of deuteration may provide crucial hints. Aims. In this context, we have measured the spectra of deuterated isotopologues of glycolaldehyde in the laboratory: the three monodeuterated ones (CH 2 OD-CHO, CHDOH-CHO and CH 2 OH-CDO) and one dideuterated derivative (CHDOH-CDO) in the ground vibrational state. Methods. Previous laboratory work on the D-isotopologues of glycolaldehyde was restricted to less than 26 GHz. We used a solidstate submillimeter-wave spectrometer in Lille with an accuracy for isolated lines better than 30 kHz to acquire new spectroscopic data between 150 and 630 GHz and employed the ASFIT and SPCAT programs for analysis. Results. We measured around 900 new lines for each isotopologue and determined spectroscopic parameters. This allows an accurate prediction in the ALMA range up to 850 GHz Conclusions. This treatment meets the needs for a first astrophysical research, for which we provide an appropriate set of predictions.
Green Bank Telescope Observations of Interstellar Glycolaldehyde: Low-Temperature Sugar
The Astrophysical Journal, 2004
Interstellar glycolaldehyde (CH 2 OHCHO) has been detected with the 100 m Green Bank Telescope (GBT) toward the star-forming region Sagittarius B2(N) by means of the 1 10 -1 01 , 2 11 -2 02 , 3 12 -3 03 , and 4 13 -4 04 rotational transitions at 13.48, 15.18, 17.98, and 22.14 GHz, respectively. An analysis of these four high signal-to-noise ratio rotational transitions yields a glycolaldehyde state temperature of ∼8 K. Previously reported emission-line detections of glycolaldehyde with the NRAO 12 m telescope at millimeter wavelengths (71-103 GHz) are characterized by a state temperature of ∼50 K. By comparison, the GBT detections are surprisingly strong and are seen in emission at 13.48 GHz, emission and absorption at 15.18 GHz, and absorption at 17.98 and 22.14 GHz. We attribute the strong absorption observed by the GBT at the higher frequencies to the correspondingly smaller GBT beams coupling better to the continuum source(s) in Sagittarius B2(N). A possible model for the two-temperature regions of glycolaldehyde is discussed. Subject headings: ISM: abundances -ISM: clouds -ISM: individual (Sagittarius B2(N-LMH)) -ISM: molecules -radio lines: ISM L46 HOLLIS ET AL. Vol. 613
The Spatial Scale of Glycolaldehyde in the Galactic Center
The Astrophysical Journal, 2001
We previously reported the spectral detection of the first interstellar sugar, which is known as glycolaldehyde (CH 2 OHCHO), by observing six separate millimeter-wave rotational transitions with the NRAO 12 m telescope while pointed toward the Sagittarius B2 North hot core source known as the Large Molecule Heimat (LMH) source. In the present BIMA array work, we have spatially mapped Sgr B2 using the 8 08 -7 17 transition of glycolaldehyde at 82.4 GHz. We find that glycolaldehyde has a spatial scale of ≥60Љ unlike its isomers methyl formate and acetic acid, which are concentrated in the LMH source that has a spatial scale of ≤5Љ. We estimate that the relative abundance ratios of (acetic acid) : (glycolaldehyde) : (methyl formate) are ∼1 : 0.5 : 26 within the LMH source. It is likely that the conditions of the LMH source favor the chemically reactive nature of glycolaldehyde over its isomers and other large molecules such as dimethyl ether. The ensuing chemistry leads to glycolaldehyde destruction in the LMH source and glycolaldehyde survival outside of the LMH source in extended cloud extremities. This scenario is supported by comparison of line widths, which shows that glycolaldehyde possesses a factor of 2-3 greater line width than those of other complex molecules that are confined largely to the LMH source.
Microwave Spectroscopy of Astrophysical Molecules
Highlights of Astronomy, 1989
Recent detections of new molecules in dense interstellar clouds, first detections of certain chemical elements in interstellar molecules, and new information on isotopic fractionation of hydrogen in the interstellar medium are discussed in the context of the need for new laboratory data on transition rest frequencies, reaction rates, and branching ratios.
CH 3 GHz Observations of Molecular Clouds along the Galactic Plane
The Astronomical Journal, 2005
Spectra in the CH 2 Π 1/2 , J=1/2, F=1-1 transition at 3335 MHz were obtained in three 5-point crosses centered on the Galactic plane at ℓ = 50 • , 100 • , and 110 • . The lines of sight traverse both Giant Molecular Clouds (GMCs) and local, smaller entities. This transition is a good tracer of low-density molecular gas and the line profiles are very similar to CO(1-0) data at nearly the same resolution. In addition, the CH 3335 MHz line can be used to calibrate the CO-H 2 conversion factor (X CO ) in low-density molecular gas. Although this technique underestimates X CO in GMCs, our results are within a factor of two of X CO values calibrated for GMCs by other techniques. The similarity of CH and CO line profiles, and that of X CO values derived from CH and more traditional techniques, implies that most of the molecular gas along the observed lines of sight is at relatively low densities (n ≤ 10 3 cm −3 ).
Monthly Notices of the Royal Astronomical Society
Glycolaldehyde (CH2OHCHO) is the simplest monosaccharide sugar in the interstellar medium, and it is directly involved in the origin of life via the ‘RNA world’ hypothesis. We present the first detection of glycolaldehyde (CH2OHCHO) towards the hot molecular core G358.93–0.03 MM1 using the Atacama Large Millimeter/Submillimeter Array (ALMA). The calculated column density of CH2OHCHO towards G358.93–0.03 MM1 is (1.52 ± 0.9) × 1016 cm−2 with an excitation temperature of 300 ± 68.5 K. The derived fractional abundance of CH2OHCHO with respect to H2 is (4.90 ± 2.92) × 10−9, which is consistent with that estimated by existing two-phase warm-up chemical models. We discuss the possible formation pathways of CH2OHCHO within the context of hot molecular cores and hot corinos and find that CH2OHCHO is likely formed via the reactions of radical HCO and radical CH2OH on the grain surface of G358.93–0.03 MM1.
Methanol is observed in a wide range of astrophysical sources throughout the universe, and comprehensive databases of the millimeter and THz spectra of CH 3 OH and its principal isotopologues represent important tools for the astronomical community. A previous combined analysis of microwave and millimeter wave spectra of 13 CH 3 OH together with Fourier transform far-infrared spectra was limited to the first two torsional states, m t = 0 and 1, for J values up to 20. The limits on frequency and quantum number coverage have recently been extended by new millimeter and THz measurements on several different spectrometers in the Cologne laboratory in the frequency windows 34-70 GHz, 75-120 GHz, 240-340 GHz, 360-450 GHz and 1.12-1.50 THz. With the new data, the global treatment has now been expanded to include the first three torsional states for J values up to 30. The current 13 CH 3 OH data set contains about 2300 microwave, millimeter-wave, sub-millimeter and THz lines and about 17,100 Fourier-transform far-infrared lines, representing the most recent available information in the quantum number ranges J 6 30, K 6 13 and m t 6 2. The transitions have been successfully fitted to within the assigned measurement uncertainties of ±50 kHz for most of the frequency-measured (i.e. MW, MMW, Sub-MMW, THz) lines and ±6 MHz for the FIR lines. A convergent global fit was achieved using 103 adjustable parameters to reach an overall weighted standard deviation of 1.37. Our new C-13 methanol database is improved substantially compared to the existing one , and will be available in the Cologne Database for Molecular Spectroscopy, CDMS (http://www.astro.uni-koeln.de/cdms/), in support of astronomical studies associated with results from HIFI (Heterodyne Instrument for the Far-Infrared) on the Herschel Space Observatory and new observations from SOFIA (Stratospheric Observatory For Infrared Astronomy) and ALMA (Atacama Large Millimeter/Submillimeter Array).