报告题目：High resolution Spectroscopy of small organic molecules and astrophysical molecules

报 告 人：Isabelle Kleiner Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS et Universités Paris Est-UPEC et Paris Diderot

报告时间：10月28日（星期一）上午 10:30

报告地点：物理系三楼报告厅

报告摘要：The topic of our work concerns mainly molecules containing large amplitude motions and in particular molecules containing one or two methyl (CH₃) internal rotors. One of the goals of our work is to describe with our theoretical method and codes (using effective Hamiltonians describing the rotation-torsion-vibration interactions) the energy levels and then the line positions and intensities for this type of molecules. That way we can provide reliable predictions of line positions and intensities for astrophysical molecules containing one internal rotor CH₃, such as the isotopic species ofmethyl formate HCOOCH₃, methanol CH₃OH, acetic acid CH₃COOH, acetaldehyde CH₃CHO or acetamide CH₃CONH₂. The major new facilities, the Herschel Space Observatory and the Atacama Large Millimeter Array (ALMA), in Chili, now open the sub-millimeter region up to a few THz for astronomical observations by making investigations with unprecedented high sensitivity and resolution. Molecules which undergo internal rotation of a methyl group present thousands of lines in this spectral range and therefore their spectra are particularly important to model. We will show some of the recent results in the microwave, millimeter or infrared range for those molecules. We will also present recent results for the study of a two-top internal rotor, the methyl acetate molecule CH₃-O-C(=O)-CH₃, which has been very recently detected in the interstellar cloud Orion thanks our prediction. Another goal is to get some knowledge of the structural properties of small organic molecules or biomimetic molecules. Fourier transform microwave spectroscopy in the gas phase coupled with high level quantum chemical calculations or ab initio calculations has recently led to the precise and detailed determination of molecular structures for the lowest energy conformers of a number of molecules. In this talk, we will show results from molecules which can be considered as prototypes of odorant molecules, like isoamyl acetate or linalool, an acyclic mono-terpene.