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

Abstract

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.

Laboratory Detection of Five New Linear Silicon Carbides: SiC3, SiC5, SiC6, SiC7, and SiC8

“…Linear has recently been detected in the visible by C 5 cavity ringdown spectroscopy (Motylewski et al 1999), and it may be possible to detect the electronic spectra of the silicon carbides here in the same way. The optical bands of have long been observed in the atmospheres of cool SiC 2 stars (Merrill 1926 ;Sanford 1926) and in the laboratory (Butenho † & RohlÐng 1991, and references therein), but the optical spectra of longer silicon carbides have not been reported.…”

An upper limit to the interstellar $\vec{C_5}$ abundance in translucent clouds

“…Is it a spectral signature of the C 5 chain molecule? If yes, we should observe in the same spectra another spectral feature, situated around 5109 Å (Motylewski et al 1999) being of the same equivalent width but a bit broader. To check this we have first averaged 32 of the R = 120 000 spectra acquired at Terskol Observatory.…”

“…Motylewski et al 1999). The spectra of still longer chains are known only from the matrix isolation spectroscopy and are thus difficult to be directly compared to astrophysical spectra.…”

“…The visual spectrum of C 5 consists of four features, discovered in laboratory gas-phase experiments, but only two of them, situated near 4975 and 5109 Å, should be strong enough to allow observational detection (Motylewski et al 1999). The features found in laboratory are narrow and thus high resolution spectral observations are highly desirable.…”

The interstellar $\mathsf{{\vec C}_3}$ chain molecule in different interstellar environments

“…Motylewski et al 1999). The first pure carbon molecule, the two-atom homonuclear C 2 , was discovered by means of near infrared spectroscopy in 1977 by Souza & Lutz in the spectrum of the opaque cloud obscuring the star Cyg OB2 No.…”