Knowledge Bank

The absorption spectrum of the weakly bound complex $CO2-Br2$ has been observed by probing the asymmetric stretch of the $CO2$ moiety near $2349cm-1$. Complex was formed by supersonic expansion of the mixture of $CO2$ and bromine vapor with use He as a carrier gas. The $CO2-Br2$ was found to have a linear structure with a Br atom close to the center of mass of the system. The isotope substitution of the other Br provided the splitting of the observed peaks into two. The measured rotational and distortional constants for $\mathrm{<mrow\; data-mjx-texclass="ORD">79</mrow>}Br$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">81</mrow>}Br$ are $B\prime =0.0148044(26),D\prime =6.43(17)\times 10-8,B\prime =0.0146591(26),D\prime =6.01(18)\times ;10-8$, and $B\prime =0.0146765(27),D\prime =6.42(18)\times ;10-8,B\prime =0.0145322(28),D\prime =6.03(19)\times ;10-8$, respectively(in $cm-1$)The experimental values will be compared with ab initio calculation results and the floppiness of the molecule will be discussed.