The Vibrational Predissociation and Intramolecular Vibrational Redistribution of the C₃Ar van der Waals Complex Studied by Fragment Emission

Sheng-Chang Hsiao^1*, Yen-Chu Hsu^1,2

¹Department of Physics, National Central University, Taoyuan, Taiwan
²Institute of Atomic and Molecular Sciences,Academia Sinica, Taipei, Taiwan

* Presenter:Sheng-Chang Hsiao, email:j1997616@gmail.com

The emission spectra of 12 vibrational levels of the first electronically excited state of C₃Ar have been recorded in the spectral region of 379.5-381.2 nm. These 12 vibrational levels lie at ~1600 cm^-1 with the C₃ vibrational assignments of 0 8^- 0, 0 4⁺0, and 0 0 2. The emission primarily consists of the Ã-(X ̃ )bands of the C₃ fragments. The collected emission spectral intensity of a given C₃ fragment can be used to build the distribution of the fragment branching ratio versus the energy of its translational and rotational motion released after the predissociation. Some of the distributions follow the momentum gap law or energy gap law, but not some others, and the latter cannot be described with Gaussian functions either. In this work, we propose a Franck-Condon type picture to explain the observed fragment distributions. Since the lifetimes of these vibrational levels are generally short (≦50ps) due to the vibrational predissociation, it allowed us to observe the early stage of the intramolecular vibrational relaxation pathways within the complex.

Keywords: van der Waals complex, vibrational predissociation, Atom-Molecular Optical Physics