THE SPECTRUM OF THE ICCH DIMER IN THE $3330 CM^{-1}$ REGION.

Abstract

We have obtained the ICCH dimmer spectrum in the fundamental C-H stretch region ($3330 cm^{-1}$) using molecular beam, optothermal detection. Only one A,B hybrid band was observed. A simulation of this spectrum was done yielding the following rotational constants: $A=0.106592 cm^{-1}, B^{\prime\prime}=0.010250 cm^{-1}$ and $C^{\prime}=0.009290 cm^{-1}$ for the ground state and for the excited state: $A^{\prime}=0.106582, B^{\prime}=0.010249 cm^{-1}$ and $C^{\prime}=0.009289 cm^{-1}$. The position of the lines is accurately predicted by the rigid rotor model, but the intensities are not. Especially at low J unresolved hyperfine structure is present. We have calculated the vibrationally averaged geometries which are consistent with the measured rotational constants. We tentatively assign to the dimer a T shaped geometry, based on the relative intensities for the A and B type transitions.