Rotational and hyperfine analysis of the A²∑⁺ - X₁²π_3/2 and B²∑^- - X₁²π_3/2 transitions of AuS

Abstract

We have recorded the ${\text{A}}^2{\mathrm{\Sigma }}^{+}-{{\text{X}}_1}^2{\mathrm{\Pi }}_{3/2}$ (0,0) and ${\text{B}}^2{\mathrm{\Sigma }}^{-}-{{\text{X}}_1}^2{\mathrm{\Pi }}_{3/2}$ (0,0) bands of gold monosulphide (AuS) at sub-Doppler resolution by intermodulated fluorescence spectroscopy. These two red-degraded bands lie at 642.3  and 613.8 nm, respectively. The high resolution of the experiment enabled the accurate determination of the rotational, fine and ¹⁹⁷Au hyperfine constants of the two excited states for the first time. The Fermi contact dipolar and electric quadrupolar interactions in the upper states can be understood in terms of the electronic configurations from which they arise. The signs of the spin–rotation parameters, γ(A²Σ⁺) = −0.080821(24) cm⁻¹ and γ(B²Σ⁻) = 0.136427(20) cm⁻¹, suggest that the fine structures of these states arise primarily by interactions with inverted ²Π states lying at higher energy.

GRAPHICAL ABSTRACT

KEYWORDS:

• Gold sulfide
• AuS
• electronic spectroscopy
• hyperfine

Acknowledgment

The authors are grateful to Timothy C. Steimle (Arizona State Univ.) for helpful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Science Foundation under Grants CHE-1265741 and CHE-1565969.