15min:

SIEGHARD ALBERT AND MARTIN QUACK, Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland.

Space-based observatories like the Infrared Space Observatory (ISO) and satellite missions like Cassini to Titan give us new insights into interstellar and planetary chemistry, the synthesis of ``prebiotic'' molecules and thus their role in the origin of life. One of the most challenging tasks is the identification of molecules which are important in the synthesis of biomolecules like DNA. A prominent species is pyrimidine (C₄H₄¹⁴N₂). Pyrimidine has not yet been unambiguously identified in the interstellar medium by microwave spectroscopy. For that reason we provide new high resolution infrared spectra of pyrimidine which may make it possible to confirm the detection of extraterrestial pyrimidine in the infrared region. We have recorded the spectrum of pyrimidine in the region 600-3600~cm^-1 with our Zürich Bruker 2001 prototype Fourier transform infrared spectrometer\footnote S.~Albert, K.K. Albert, and M.~Quack, Trends in Optics and Photonics 84, 177 (2003). with an instrumental resolution of 0.0008~cm^-1, essentially Doppler-limited, with Doppler widths ranging from 0.0008 to 0.0015~cm^-1. The analysis of the bands located at _c=714.54106~cm^-1 ( ₄) and _c=803.97947~cm^-1 ( _10b) will be discussed. The _6b band rotationally assigned by Kisiel et al. was also analysed ( _c=620.54976~cm^-1). In addition, we have measured the rovibrationally resolved FTIR spectra of other aromatic compounds containing heteroatoms like aniline (C₆H₇N), phenol (C₆H₆O), and benzaldehyde (C₇H₆O) in the range 600-1300~cm^-1. We will show an initial assignment of these spectra, which are rather complicated due to the excitation of inversion and torsion modes. In this context we will discuss the absorption features in the region between 650 and 1000~cm^-1 detected in the ISO spectra from the proto-planetary nebula CRL~618.