Vibronic structures of the Ã-X̃ and B̃-X̃ bands of the HgAr2 triatomic cluster were investigated by laser-induced fluorescence (LIF) spectroscopy. The LIF spectra of the Ã-X̃ and B̃-X̃ bands of HgAr2 were observed free from hindrance of strong A-X and B-X transitions of HgAr by monitoring the fluorescence in the visible region. The analysis of the vibronic structures led to the fundamental frequencies of ω1=26.3(3), ω2=12.0(5), and ω3=28.1(4) cm-1 for the Ã state and ω1=9.2(3) and ω2=23.8(6) cm-1 for the B̃ state, where subscripts "1," "2," and "3," respectively, denote symmetric stretching, bend, and asymmetric stretching modes. A number in parentheses represents an estimated limit of error (σ). It was found that HgAr2 in the B̃ state predissociates to produce HgAr(A)+Ar. The vibrational and rotational distributions of the HgAr fragment in the A state were derived by observing LIF spectra of the E-A band. Based on these distributions, level energies of HgAr2 in the B̃ state were estimated with respect to those of HgAr in the A state, and then, the dissociation energies (De) of HgAr2 to Hg+Ar+Ar were derived to be 374(2), 540(2), and 249(2) cm-1 for the X̃, Ã, and B̃ states, respectively. The vibronic structure of HgAr2 in the lowest Rydberg (Ẽ) state associated with Hg (7 3S1) was investigated by the optical-optical double resonance spectroscopy via the Ã state. The geometrical structure, in which an outer Ar atom is loosely bound to the Rydberg-type HgAr core, that is close to HgAr+, is proposed for the Ẽ state, and a presence of large amplitude motion of the outer Ar atom is deduced from the obtained fundamental frequencies of ω1=102. 1(3) and ω2=5.4(2) cm-1, where subscripts "1" and "2" denote a stretching mode of the HgAr core and the Ar-Hg-Ar bending mode.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry