According to traditional quantum chemistry involving only the electromagnetic force the ground state energies of the enantiomers of chiral molecules as well as the energies of equivalent excited quantum states are exactly identical by symmetry. When the parity violating weak "nuclear" force causing beta-decay is included in the "electroweak quantum chemistry", one predicts an energy difference Δ_pvE₀ between the ground states of enantiomers and a corresponding reaction enthalpy Δ_pvH₀^Θ for the stereomutation reaction converting P and M enantiomers in the case of axially chiral molecules, [1, 2]:

P = M         Δ_pvH₀^Θ = E₀(M) - E₀(P) = N_AΔ_pvE₀       (1)

We report the first successful high-resolution analyses of the Fourier transform infrared (FTIR) spectrum of trisulfane. A band centered at 861.0292 cm^-1 can be assigned unambiguously to the chiral trans conformer by means of ground state combination differences in comparison with known rotational spectra. A second band near 864.698 cm^-1 is tentatively assigned to the cis conformer by comparison with theory. The results are discussed in relation to their importance for experimental attempts to measure the parity violating energy difference Δ_pvE between the ground states of enantiomers of chiral molecules, [3, 4].

[1] M. Quack Fundamental Symmetries and Symmetry Violations from High-Resolution Spectroscopy, Vol. 1, pp. 659-722 in Handbook of High Resolution Spectroscopy, M. Quack and F. Merkt eds., Wiley Chichester 2011.
[2] C. Fabri, L. Horny, M. Quack, ChemPhysChem, 2015, 16, 3584.
[3] P. Dietiker, E. Miloglyadov, M. Quack, A. Schneider, and G. Seyfang, Journal of Chemical Physics 2015 143, 244305.
[4] S. Albert, I. Bolotova, Z. Chen, C. Fabri, M. Quack, G. Seyfang, D. Zindel, Physical Chemistry Chemical Physics 2017, 19, 11738.