Discovery of interstellar methyl formate

Brown, Rodney D.; Crofts, Jonathan G.; Gardner, F. F.; Godfrey, Peter D.; Robinson, B. J.; Whiteoak, J. B.

doi:10.1086/181769

Cited by 121 publications

(100 citation statements)

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“…It was identified in different sources since 1975 (Brown et al 1975;Churchwell et al 1975); nearly one thousand lines were detected in the ground-torsional state v t = 0. Its abundance is particularly high in Orion-KL: it was detected up to 900 GHz (Comito et al 2005) far from the maximum of absorption situated around 300 GHz; some lines from the first (Kobayashi et al 2007), and more recently, lines from the second torsional state were detected (Takano et al 2012).…”

Section: Introductionmentioning

confidence: 99%

THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

Haykal¹,

Carvajal²,

Tercero³

et al. 2014

A&A

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Context. An astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range of organic molecules to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict the transitions frequencies very precisely that were not measured in the laboratory. Aims. We present the experimental study and its theoretical analysis for two 13 C-methyl formate isotopologues to detect these two isotopologues for the first time in their excited torsional states, which lie at 130 cm −1 (200 K) in Orion-KL. Methods. New spectra of HCOO 13 CH 3 ( 13 C 2 ) methyl formate were recorded with the mm-and submm-wave spectrometer in Lille from 50 to 940 GHz. A global fit for v t = 0 and 1 was accomplished with the BELGI program to reproduce the experimental spectra with greater accuracy. Results. We analysed 5728 and 2881 new lines for v t = 0 and 1 for HCOO 13 CH 3 . These new lines were globally fitted with 846 previously published lines for v t = 0. In consequence, 52 parameters of the RAM Hamiltonian were accurately determined and the value of the barrier height (V 3 = 369.93168(395) cm −1 ) was improved. We report the detection of the first excited torsional states (v t = 1) in Orion-KL for the 13 C 2 and 13 C 1 methyl formate based on the present analysis and previously published data. We provide column densities, isotopic abundances, and vibrational temperatures for these species. Conclusions. Following this work, accurate prediction can be provided. This permits detecting 135 features of the first excited torsional states of 13 C-methyl formate isotopologues in Orion-KL in the 80−280 GHz frequency range, without missing lines.

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Section: Introductionmentioning

confidence: 99%

THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

Haykal¹,

Carvajal²,

Tercero³

et al. 2014

A&A

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“…Methyl formate may provide a connection to acetic acid (CH 3 COOH) and even to glycine (NH 2 CH 2 COOH), the simplest biologically important amino acid. The first detection of interstellar methyl formate was made by Brown et al (1975) toward the star-forming region Sgr B2. After it has been detected in several hot cores, in three hot corinos (Bottinelli et al 2007), and in comets (Bockelée-Morvan et al 2000;Despois et al 2005;.…”

Section: Introductionmentioning

confidence: 99%

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Modica¹,

Palumbo²

2010

A&A

102

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Context. Methyl formate (HCOOCH 3 ) is a complex organic molecule detected in hot cores and hot corinos. Gas-phase chemistry fails to reproduce its observed abundance, which usually varies between 10 −7 and 10 −9 with respect to H 2 . Aims. Laboratory experiments were performed in order to investigate a solid-state route of methyl formate formation, to obtain an estimate of the amount that can be formed, and to verify whether it can account for the observed abundances. Methods. Several solid samples (16 K) of astrophysical interest were analyzed by infrared spectroscopy in the 4400−400 cm −1 range. The infrared spectral characteristics of frozen methyl formate were studied by deriving their band strength values. The effects produced upon warm-up of the samples were analyzed comparing the spectra taken at different temperatures. In order to study the formation and destruction mechanism of methyl formate in the interstellar ices, a binary mixture of methanol (CH 3 OH) and carbon monoxide (CO) ice and a sample of pure methanol were irradiated at 16 K with 200 keV protons. Methyl formate was identified through its fundamental mode (CH 3 rocking) at about 1160 cm −1 . Results. We present the mid-infrared methyl formate ice spectrum showing both the amorphous (16 K) and the crystalline (110 K) structure. We report novel measurements of the band strength values of the six main methyl formate bands. We prove the formation and the destruction of methyl formate after irradiation of CH 3 OH and a CO:CH 3 OH mixture. Extrapolating our results to the interstellar medium conditions we found that the production timescale of methyl formate agrees well with the evolutionary time of molecular clouds. The comparison with the observational data indicates that the amount of methyl formate formed after irradiation can account for the observed abundances. Conclusions. The present results allow us to suggest that gas phase methyl formate observed in dense molecular clouds is formed in the solid state after cosmic ion irradiation of icy grain mantles containing CO and CH 3 OH and released to the gas phase after desorption of icy mantles.

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“…In 1959 Curl studied the chemical structure and the microwave spectrum of the parent methyl formate and 8 other isotopologues (Curl 1959). In 1975 the parent molecule was detected for the first time in the interstellar medium by Brown et al (1975) and Churchwell et al (1975). Since this discovery, approximately 900 lines of the ground torsional state have been detected in different interstellar molecular clouds, Sgr B2, Orion KL, and W51 e1/e2 (Lovas 2004).…”

Section: Introductionmentioning

confidence: 99%

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion

Carvajal¹,

Margulès

Tercero

et al. 2009

A&A

116

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Context. Laboratory measurements and analysis of the microwave and millimeter-wave spectra of potential interstellar molecules are a prerequisite for their subsequent identification by radioastronomical techniques. The spectral analysis provides spectroscopic parameters that are used in the assignment procedure of the laboratory spectra, and that also predict the frequencies of transitions not measured in the laboratory with a high degree of precision.Aims. An experimental laboratory study and its theoretical analysis is presented for 13 C 2 -methyl formate (HCOO 13 CH 3 ) allowing a search for this isotopologue in the Orion molecular cloud. The 13 C 1 -methyl formate (H 13 COOCH 3 ) molecule was also searched for in this interstellar cloud, using previously published spectroscopic data. Methods. The experimental spectra of 13 C 2 -methyl formate were recorded in the microwave and sub-mm energy ranges (4-20 GHz, 8-80 GHz, 150-700 GHz). The spectra were analyzed using the Rho-Axis Method (RAM), which takes the CH 3 internal rotation and the coupling between internal rotation and global rotation into account. Results. Twenty-seven spectroscopic constants of 13 C 2 -methyl formate have been obtained from a fit of 936 transitions of the ground torsional state with a standard (unitless) deviation of 1.08. A prediction of line positions and intensities is also produced. This prediction allowed us to identify 230 13 C 2 -methyl formate lines in the Orion interstellar molecular cloud. We refitted all previously published ground state transitions of the 13 C 1 -methyl formate molecule in order to provide a prediction of its ground state spectrum. 234 lines of 13 C 1 -methyl formate were detected in the Orion interstellar cloud using that prediction.

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Discovery of interstellar methyl formate

Cited by 121 publications

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THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion

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Discovery of interstellar methyl formate

Cited by 121 publications

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THz spectroscopy and first ISM detection of excited torsional states of13C-methyl formate

THz spectroscopy and first ISM detection of excited torsional states of13C-methyl formate

Formation of methyl formate after cosmic ion irradiation of icy grain mantles

Rotational spectrum of13C2-methyl formate (HCOO13CH3) and detection of the two13C-methyl formate in Orion

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THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

THz spectroscopy and first ISM detection of excited torsional states of¹³C-methyl formate

Rotational spectrum of¹³C₂-methyl formate (HCOO¹³CH₃) and detection of the two¹³C-methyl formate in Orion