Ab Initio Study of the Rotational‐Torsional Spectrum of Methyl Formate

Senent, María Luisa; Villa, M.; Meléndez, Francisco J.; Domı́nguez-Gómez, R.

doi:10.1086/430201

Cited by 53 publications

(63 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lately new spectroscopic measurements of monodeuterated species HCOOCH 2 D were carried out by Margules et al (2009). Finally, besides the spectroscopic studies mentioned above, the molecular structure of the main isotopologue of methyl formate has been determined from ab initio calculations (Uchimaru et al 2003;Senent et al 2005), which confirmed the experimental values already obtained for the torsional and rotational parameters.…”

Section: Introductionsupporting

confidence: 79%

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

Carvajal¹,

Margulès

Tercero

et al. 2009

A&A

116

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 79%

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

Carvajal¹,

Margulès

Tercero

et al. 2009

A&A

116

View full text Add to dashboard Cite

show abstract

“…The former motion has a large potential barrier V connecting two potential minima of %5000 cm À1 with respect to the global potential minimum (1 cm À1 ¼ 0:695 K ). As a result, methyl formate has two stable conformers, referred to as cis and trans (Senent et al 2005), where the labels correspond to the position of the double-bonded oxygen atom with respect to the methyl (CH 3 ) top. The trans conformer lies as high as 1700 cm À1 above the cis conformer (Senent et al 2005) and is difficult to observe at room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, methyl formate has two stable conformers, referred to as cis and trans (Senent et al 2005), where the labels correspond to the position of the double-bonded oxygen atom with respect to the methyl (CH 3 ) top. The trans conformer lies as high as 1700 cm À1 above the cis conformer (Senent et al 2005) and is difficult to observe at room temperature. On the other hand, the three-fold internal rotation of the methyl group leads to a series of thermally populated torsional levels, each of which is split into two torsional substates, with A and E symmetries.…”

Section: Introductionmentioning

confidence: 99%

The Millimeter‐ and Submillimeter‐Wave Spectrum of¹³C₁‐Methyl Formate (H¹³COOCH₃) in the Ground State

Maeda

Medvedev

Lucia

et al. 2008

ASTROPHYS J SUPPL S

View full text Add to dashboard Cite

A large number of rotational transitions of 13 C 1 -methyl formate in its ground A and E torsional substates were measured in the 110Y380 GHz region with the Fast Scan Submillimeter Spectroscopic Technique (FASSST). Besides strong a-type transitions, many b-type transitions through rotational quantum numbers J 00 ¼ 59 and K 00 a ¼ 16 were newly measured, and some forbidden c-and x-type transitions in the E substate were also assigned. The new lines were analyzed together with previous submillimeter-wave data using an effective rotational-torsional Hamiltonian method designated ''ERHAM'' developed for a molecule with one or two internal rotors. In total, over 4900 transitions of 13 C 1 -methyl formate were analyzed. Systematic deviations due to perturbations were found in Q-branch transitions at high J, and higher order Coriolis-type interaction terms were included to fit the data better. A standard deviation of 86 kHz was obtained by varying 33 parameters. In addition to 13 C 1 -methyl formate, the normal isotopologue was studied anew and some high-K a transitions were newly assigned. The previous data of the normal species in the ground state were reanalyzed with the ERHAM method together with new transitions measured in the present study. The same deviations in Q-branch transitions, not observed in previous studies, were also found in the normal species. Using spectroscopic parameters obtained in this study, predictions have been made for many strong lines of 13 C 1 -methyl formate through 620 GHz in frequency not analyzed in the fit.

show abstract

“…15 For nonrigid molecules, the theory can help in understanding many aspects related to the effects of barriers on the splitting of the levels. [16][17][18] To take all these effects into consideration, the torsional spectrum of EME is studied, in this paper, from a CCSD͑T͒ three-dimensional potential energy surface ͑3D-PES͒ and a flexible variational model. The 3D-PES determi-nation ͑12 atoms; 181 optimized geometries + zero vibrational energy correction͒ has carried out a large computational effort.…”

Section: Introductionmentioning

confidence: 99%

CCSD(T) study of the far-infrared spectrum of ethyl methyl ether

Senent¹,

Ruiz²,

Villa³

et al. 2009

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

Band positions and intensities for the far-infrared bands of ethyl methyl ether are variationally determined from a three-dimensional ͑3D͒ potential energy surface calculated with CCSD͑T͒/ cc-pVTZ theory. For this purpose, the energies of 181 selected geometries computed optimizing 3n − 9 parameters are fitted to a 3D Fourier series depending on three torsional coordinates. The zero point vibrational energy correction and the search of a correct definition of the methyl torsional coordinate are taken into consideration for obtaining very accurate frequencies. In addition, second order perturbation theory is applied on the two molecular conformers, trans and cis-gauche, in order to test the validity of the 3D model. Consequently, a new assignment of previous experimental bands, congruent with the new ab initio results, is proposed. For the most stable trans-conformer, the 30 , 29 , and 28 fundamental transitions, computed at 115.3, 206.5, and 255.2 cm −1 , are correlated with the observed bands at 115.4, 202, and 248 cm −1 . For the cis-gauche the three band positions are computed at 91.0, 192.5, and 243.8 cm −1 . Calculations on the −d 3 isotopomer confirm our assignment. Intensities are determined at room temperature and at 10 K. Structural parameters, potential energy barriers, anharmonic frequencies for the 3n − 9 neglected modes, and rotational parameters ͑rotational and centrifugal distortion constants͒, are also provided.

show abstract

Ab Initio Study of the Rotational‐Torsional Spectrum of Methyl Formate

Cited by 53 publications

References 37 publications

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

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

The Millimeter‐ and Submillimeter‐Wave Spectrum of¹³C₁‐Methyl Formate (H¹³COOCH₃) in the Ground State

CCSD(T) study of the far-infrared spectrum of ethyl methyl ether

Contact Info

Product

Resources

About

Ab Initio Study of the Rotational‐Torsional Spectrum of Methyl Formate

Cited by 53 publications

References 37 publications

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

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

The Millimeter‐ and Submillimeter‐Wave Spectrum of13C1‐Methyl Formate (H13COOCH3) in the Ground State

CCSD(T) study of the far-infrared spectrum of ethyl methyl ether

Contact Info

Product

Resources

About

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

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

The Millimeter‐ and Submillimeter‐Wave Spectrum of¹³C₁‐Methyl Formate (H¹³COOCH₃) in the Ground State