Olga Vaizert

Gas-Phase Electronic Spectra of Carbon-Chain Radicals Compared with Diffuse Interstellar Band Observations

This paper compares laboratory gas-phase spectra of neutral and cationic linear carbon-chain radicals with astronomical diUuse interstellar band (DIB) spectra. The origin bands of the strong electronic tran- sitions of the studied species, (n \ 3¨6),

The 1Πu← X 1Σg+ electronic spectrum of C5 in the gas phase

The origin and three vibronic bands of the 1Πu←X 1Σg+ electronic transition of linear C5 have been observed in the gas phase. The carbon chain is produced in a slit nozzle employing both discharge and ablation techniques. Cavity ring down spectroscopy is used to measure the electronic transition. The origin band is found at 510.94(1) nm, shifted 29 cm−1 to the red of the value in a neon matrix. Intramolecular processes lead to broadening and irregularities in the rotational structure. The relation to astronomical observations is discussed.

The 3Σu−←X 3Σg− electronic spectrum of linear C4 in the gas phase

The 3Σu−←X 3Σg− electronic absorption spectrum of linear C4 has been detected in the gas phase. The origin and several vibronic transitions have been recorded by means of cavity ring down spectroscopy through a supersonic planar plasma. The origin band is found at 26 384.9(2) cm−1 (∼379 nm). A partly rotationally resolved origin band spectrum yields a value of B0′=0.1570(5) cm−1 for the electronically excited 3Σu− state.

The A 3Σ−–X 3Σ− electronic transition of HC6N

A combined matrix and gas phase study is presented to identify the A 3Σ−–X 3Σ− electronic transition of the linear triplet isomer of HC6N and isotopic derivative DC6N. Absorption spectra have been observed in a 6 K neon matrix after mass selective deposition and in the gas phase by cavity ring down spectroscopy through a supersonic planar plasma. The band origin of the 000 A 3Σ−–X 3Σ− electronic transition of HC6N is determined to be at 21 208.60(5) cm−1, shifted ∼30 cm−1 to the blue of the neon matrix value. Rotational analysis indicates that the chain is slightly stretched on electronic excitation, yielding B0′=0.027 92(5) cm−1. Transitions to vibrationally excited levels in the upper A 3Σ− state are observed as well. The results are compared with a rotationally resolved spectrum of the 000 A 3Σu−–X 3Σg− electronic transition of the isoelectronic HC7H species.

Rotationally resolved A2Πu←X 2Πg electronic transition of NC6N+

The rotationally resolved A2Πu←X2Πg electronic origin band spectrum of dicyanodiacetylene cation, NC6N+, has been recorded in the gas phase using frequency-production double modulation spectroscopy in a liquid nitrogen cooled hollow cathode discharge and cavity ring down spectroscopy in a supersonic plasma. The analysis of the complementary results provides accurate molecular parameters for the two spin-orbit components in both electronic states.

Rotationally resolved A3Σu−–X3Σg− electronic transition of NC5N

Abstract The rotationally resolved A 3 Σ u − – X 3 Σ g − electronic spectrum of the NC5N radical has been observed in the gas phase by cavity ring down spectroscopy in a supersonic plasma. The origin band is at ν 00 =22 832.7(1) cm −1 and a rotational analysis gives constants B0″=0.02799(4) and B 0 ′ =0.02778(3) cm −1 . These are compared to the Be values available from structures predicted by density functional theory and show that the molecule has a linear and centro-symmetric NCCCCCN structure.