Interstellar glycolamide: A comprehensive rotational study and an astronomical search in Sgr B2(N)

Abstract

Context. Glycolamide is a glycine isomer and also one of the simplest derivatives of acetamide (e.g., one hydrogen atom is replaced with a hydroxyl group), which is a known interstellar molecule. Aims. In this context, the aim of our work is to provide direct experimental frequencies of the ground vibrational state of glycolamide in the centimeter-, millimeter- and submillimeter-wavelength regions in order to enable its identification in the interstellar medium. Methods. We employed a battery of state-of-the-art rotational spectroscopic techniques in the frequency and time domain to measure the frequencies of glycolamide. We used the spectral line survey named Exploring Molecular Complexity with ALMA (EMoCA), which was performed toward the star forming region Sgr B2(N) with ALMA to search for glycolamide in space. We also searched for glycolamide toward Sgr B2(N) with the Effelsberg radio telescope. The astronomical spectra were analyzed under the local thermodynamic equilibrium approximation. We used the gas-grain chemical kinetics model MAGICKAL to interpret the results of the astronomical observations. Results. About 1500 transitions have been newly assigned up to 460 GHz to the most stable conformer, and a precise set of spectroscopic constants was determined. Spectral features of glycolamide were then searched for in the prominent hot molecular core Sgr B2(N2). We report the nondetection of glycolamide toward this source with an abundance at least six and five times lower than that of acetamide and glycolaldehyde, respectively. Our astrochemical model suggests that glycolamide may be present in this source at a level just below the upper limit, which was derived from the EMoCA survey. We could also not detect the molecule in the region’s extended molecular envelope, which was probed with the Effelsberg telescope. We find an upper limit to its column density that is similar to the column densities obtained earlier for acetamide and glycolaldehyde with the Green Bank Telescope.

Submillimeter-wave spectroscopy of and interstellar search for thioacetaldehyde

“…Figure 1 displays three frequency ranges that illustrate the non-detection. The LTE synthetic spectrum used to derive the upper limit to the column density of thioacetaldehyde is displayed in red and was computed assuming the same parameters (temperature, emission size, linewidth, and velocity offset with respect to the systemic velocity) as the ones we derived for acetaldehyde with the EMoCA survey [37]. These parameters are listed in Table 3, along with the parameters derived previously for methanol and methyl mercaptan in Sgr B2(N2) using the same survey [38].…”

Formation of interstellar cyanoacetamide: a rotational and computational study

“…For observations in low-frequency regions such as those available for the Green Bank Telescope (GBT) or the Effelsberg 100 m Radio Telescope, the hyperfine structure could be a drawback for interpreting the astronomical spectra. The Effelsberg observatory, for instance, has the capability to search for transitions in the microwave region such as the lines we aim to provide in this work (Sanz-Novo et al 2020). For some interstellar molecules such as cyanoallene and methanimine, the interpretation of the hyperfine pattern was moreover crucial for its conclusive identification in the ISM (Lovas et al 2006;Godfrey et al 1973).…”

“…The correlation-consistent polarized valence triple-ζ, aug-cc-pVTZ basis set including diffuse functions was used in these computations (Dunning 1989;Woon & Dunning 1993). Subsequently, the structures were reoptimized at the MP2 level (second-order Møller-Plesset perturbation theory) (Møller & Plesset 1934) and using a double-hybrid density functional (B2PLYPD) with long-range dispersion interactions (Schwabe & Grimme 2007). At the respective optimized geometries, harmonic vibrational frequencies were calculated to apply zero-point-energy corrections to the electronic energy.…”

“…These molecules are very interesting from a prebiotic point of view because the amide linkage is an essential feature in proteins. In current astronomical research, great efforts have been made to study more complex members of these molecular systems, such as glycolamide (CH 2 (OH)C(O)NH 2 ) (Sanz-Novo et al 2020).…”

Rotational spectroscopic study and astronomical search for propiolamide in Sgr B2(N)

“…The microwave spectrum of this compound was recently published (Alonso et al 2018), but the millimeter wave spectrum is still missing. On the other hand, this is not the case of glycolamide, a glycine isomer, whose millimeter wave spectrum was recorded very recently (Sanz-Novo et al 2020).…”