Global Assignment and Extension of Millimeter- and Submillimeter-wave Spectral Database of 13C1-methyl Formate (H13COOCH3) in the Ground and First Excited States

A compilation of the available spectroscopic millimeter- and submillimeter-wave data of the ground and first excited states of ¹³C₁-methyl formate (H¹³COOCH₃) has been carried out. The exhaustive analysis of the available transition lines of H¹³COOCH₃ has led to the assignment of 7457 spectral lines by means of a global fit of 45 parameters, using the Rho-Axis Method and the BELGI-Cs code, with a resulting unitless standard deviation of 0.57. Over 1600 lines are included for the first time in the fit. In addition, the line strengths of spectral lines are also calculated using the most recent experimental measurement of the electric dipole moment. In conclusion, the present study represents a notable improvement with respect to previous H¹³COOCH₃ spectral analyses. Therefore, the better accuracy of the present analysis may help the future identification of new H¹³COOCH₃ lines in the interstellar and circumstellar media, and may contribute to decrease some of the spectral confusion due to these species in astronomical surveys.