# Workshop on LABORATORY ASTROPHYSICS: Interstellar Gas, Dust and Ice

28-30 September 2016
Tagungstätte Schloss Ringberg, Kreuth
UTC timezone
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POSTERS

# High Resolution Terahertz-Spectra of the $\nu_2$-Bending Mode of Linear $\text{C}_3$ and its $^{13}\text{C}$-Isotopomers

## Speakers

• Mr. Thomas BUECHLING
• Mr. Alexander BREIER

## Content

Short carbon chains are fundamental for the chemistry of stellar and interstellar ambiences: They are omnipresent throughout the interstellar medium, they likely participate in the formation of long carbon chains and they are products in photo-fragmentation processes of larger species. Triatomic carbon, $\text{C}_3$, exhibits a mid-infrared $\nu_3$ antisymmetric stretching mode and a $\nu_2$-bending vibration at 1.9 THz. The spectroscopic investigation of the $\nu_2$-band is challenging as high resolution radiation sources in the terahertz frequency region became commercially available only recently. In our experiments we used a frequency multiplier chain at 1.8-1.9 THz driven by a 10 GHz synthesizer from Virginia Diodes Inc. to study $\text{C}_3$ molecules produced in a laser ablation source. The carbon chain molecules were cooled to rotational temperatures below 20K in an adiabatically expanding supersonic helium jet. $^{13}\text{C}$-enriched samples were used in order to study the isotopomers of linear $\text{C}_3$. Improved molecular parameters for $^{12}\text{C}^{12}\text{C}^{12}\text{C}$ and for the singly $^{13}\text{C}$-substituted species $^{13}\text{C}^{12}\text{C}^{12}\text{C}$ and $^{12}\text{C}^{13}\text{C}^{12}\text{C}$ were derived, which will foster their future interstellar detections. In addition doubly and triply substituted $^{13}\text{C}$-species were studied to derive an experimental equilibrium structure of $\text{C}_3$. All results were found in excellent agreement with a recent ab initio study by Schröder and Sebald (2016)