The 2Π ← X2Π electronic spectra of C8H and C10H in the gas phase

Abstract

The 2Π ← X 2Π electronic transition of linear C8H/C8D and C10H/C10D has been detected in the gas phase. The carbon radical chains were produced at low temperatures in a pulsed slit nozzle, incorporating a discharge in a high pressure expansion. Cavity ring down spectroscopy is used as a sensitive technique to observe the band systems in absorption. The 000 band of the 2Π3/2 ← X 2Π3/2 electronic transition of C8H in the gas phase has its origin near 15 973.5 cm−1, whereas that of C10H is around 14 000 cm−1. Some transitions involving vibrational excitation in the upper 2Π electronic state have been also detected. These measurements were undertaken because carbon chains are among the appealing candidates as carriers of diffuse interstellar bands; the observed origin bands do not show matches with the hitherto reported wavelengths. However, these gas phase data now provide a firm basis for a specific astronomical search.

Electronic spectra of C6H+ and C6H3+ in the gas phase

“…The spectra have been recorded by a pulsed cavity ringdown technique using a free jet expansion discharge with a slit nozzle [10]. The molecules were produced in a pulsed plasma, which was generated by applying 600 -900 V to a mixture of 1% HCCH or DCCD diluted in argon or helium.…”

C6H and C6D: Electronic spectra and Renner-Teller analysis

“…42,43 This large difference predicts a relatively large R-T effect (probably ε > 0.9) in the X 2 ground state of C 8 H as well. On the other hand, as a longer chain, C 8 H has more bending vibrational modes and a smaller vibrational energy for the CCC bending mode.…”

Construction of interstellar cumulenes and heterocumulenes: Mass Spectrometric Studies

“…Interestingly, highly unsaturated hydrocarbons have been nominated as possible candidates to explain these spectroscopic characteristics. Linear carbon chains of the types C n , C n H, C n H 2 , and C n H 4 (where n may be as high as 12), polycyclic aromatic hydrocarbons (PAHs) and even buckminster fullerenes have been investigated as possibilities (Leach, 1995;Linnartz et al, 1998).…”