Knowledge Bank

We are currently developing sources allowing gas phase molecular emission to be recorded by FTS in the Far Infrared region. Our preliminary results were presented last $yeara$. Improvements of the efficiency of our sources result in the observation of lower frequency molecular emission. We illustrate this with two examples. By recording the thermal vibration-rotation emission spectra of few PAH's using a new technique, the emission spectrum of anthracene was extended (for the first time to our knowledge) to its lowest frequency component located at around $87cm-1$. By using a radiofrequency discharge through a flowing mixture of $C2H4$ and $N2$, rotational emission of HCN was detected in the spectral range $30-180cm-1$. Rotational lines in pure bending motion were assigned up to the vibrational level (050). Results on HCN will be compared to those obtained by submillimeter-wave $spectroscopyb$ and infrared $spectroscopyc$.