RT Journal Article T1 Rotational spectrum of 13C2-methyl formate (HCOO13CH3) anddetection of the two 13C-methyl formate in Orion A1 Kleiner, I. A1 Carvajal Zaera, Miguel A1 Margulès, L. A1 Tercero, B. A1 Demyk, K. A1 Guillemin, J. C. A1 Lattanzi, V. A1 Walters, A. A1 Demaison, J. A1 Wlodarczak, G. A1 Huet, Thérèse R. A1 Møllendal, H. A1 Ilyushin, V. V. A1 Cernicharo, J. AB Laboratory measurements and analysis of the microwave and millimeter-wave spectra of potential interstellar moleculesare a prerequisite for their subsequent identification by radioastronomical techniques. The spectral analysis provides spectroscopicparameters that are used in the assignment procedure of the laboratory spectra, and that also predict the frequencies of transitions notmeasured in the laboratory with a high degree of precision.Aims. An experimental laboratory study and its theoretical analysis is presented for 13C2-methyl formate (HCOO13CH3) allowing asearch for this isotopologue in the Orion molecular cloud. The 13C1-methyl formate (H13COOCH3) molecule was also searched forin this interstellar cloud, using previously published spectroscopic data.Methods. The experimental spectra of 13C2-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 CH3 internal rotation andthe coupling between internal rotation and global rotation into account.Results. Twenty-seven spectroscopic constants of 13C2-methyl formate have been obtained from a fit of 936 transitions of the groundtorsional state with a standard (unitless) deviation of 1.08. A prediction of line positions and intensities is also produced. This predictionallowed us to identify 230 13C2-methyl formate lines in the Orion interstellar molecular cloud.We refitted all previously publishedground state transitions of the 13C1-methyl formate molecule in order to provide a prediction of its ground state spectrum. 234 linesof 13C1-methyl formate were detected in the Orion interstellar cloud using that prediction. PB EDP Sciences SN 0004-6361 YR 2009 FD 2009-06 LK http://hdl.handle.net/10272/5424 UL http://hdl.handle.net/10272/5424 LA eng NO Carvajal Zaera, M., Margulès, L., Tercero, B., Demyk, K.,Kleiner, I., Guillemin, J. C., Lattanzi, V., Walters, A., Demaison, J., Wlodarczak, G., Huet, T. R., Ilyushin, V. V., Møllendal, H., Cernicharo, J.: "Rotational spectrum of 13C2-methyl formate (HCOO13CH3) and detection of the two 13C-methyl formate in Orion". Astronomy and Astrophysics. Vol. 500, n. 3, p. 1109-1118 (2009). ISSN 0004-6361 DS Repositorio Institucional de la Universidad de Huelva RD 30 may 2026