The Electronic and Pure Rotational Spectra of the PCN Free Radical
Abstract
Optical, millimeter-wave and Fourier transform microwave (FTMW) spectra of the PCN free radical have been observed in the laboratory. Laser-induced fluorescence (LIF) studies at the University of Kentucky showed that PCN can be produced in an electric discharge using phosphorus trichloride/cyanogen or phosphorus/cyanogen precursor mixtures in argon. The observed LIF spectrum of PCN in the near-ultraviolet was assigned as the 3Π - 3Σ- electronic transition and single vibronic level emission spectra show activity in the ν1(CN stretch) = 1991 cm-1 and ν3(PC stretch) = 658 cm-1 vibrational modes. The pure rotational spectrum was measured at the University of Arizona by direct absorption and FTMW emission techniques. Twenty-four rotational transitions were measured in the frequency range of 137 to 413 GHz, as well as three rotational transitions from 19 to 34 GHz. Each transition is split into three fine-structure components, due to spin-rotation and spin-spin interactions. Below 277 GHz, hyperfine interactions due to the phosphorus nuclear spin of I = 1/2 are evident, spitting each line into doublets. In the microwave region, nitrogen hyperfine structure further splits each line into three components. The rotational, fine-structure, phosphorus and nitrogen hyperfine constants and the molecular structure have been determined. Given the recent detections of HCP and CCP, PCN is a possible interstellar/circumstellar species.
- Publication:
-
American Astronomical Society Meeting Abstracts #212
- Pub Date:
- May 2008
- Bibcode:
- 2008AAS...212.0319Z