The hole burning spectroscopy of the C₃Ar van der Waals complex

Yen-Chu Hsu^1,2*, Yi-Jen Wang²

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

* Presenter:Yen-Chu Hsu, email:ychsu@po.iams.sinica.edu.tw

The C₃Ar van der Waals complex has been studied under supersonic expansion conditions by laser-induced fluorescence and hole burning techniques. The spectrum of the complex consists of a number of pairs of bands accompanying each of the bands of the A-X system of C₃,^1,2 other than the perturbed 000-000 band. In this work the two longest wavelength pairs are assumed to form a vibrational progression with an upper state frequency of about 12 cm^-1. Somewhat unexpectedly, the two lowest pairs exhibit very different dynamics. The two members of the lowest pair have more diffuse rotational structure; also compared to the next pair, their upper states predissociate into lower (by about 100 ^-1) vibrational states of the C₃ fragment. A hole burning experiment has been carried out which proves that the lowest pair indeed belongs to C₃Ar, and arises from its ground vibrational level. Band contour calculations of the rotational envelopes show that the two lowest rotational pairs have the same upper state symmetries and the rotational constant B' of one member is unusually large, indicating the prescene of Coriolis coupling within the pairs. The 12 cm^-1 vibrational frequency is tentatively assigned as two quanta of the out-of-plane bending vibration, based on the analogy of the ground-state vibrational frequency. Band contour simulations of the hole burning spectra will be presented and discussed.

References,
1. G. Zhang, B.-G. Lin, S.-M. Wen, and Y.-C. Hsu, J. Chem. Phys. 120, 3189-3200(2004).
2. A. J. Merer, Y.-C. Hsu, Y.-R. Chen, and Y.-J. Wang, J. Chem. Phys. 143, 194304(2015).

Keywords: structure and dynamics of van der Waals complex, predissociation, atomic and molecular interaction