High-Resolution Spectroscopic Studies and Theory of Parity Violation in Chiral Molecules

Abstract

We review the high-resolution spectroscopic approach toward the study of intramolecular dynamics, emphasizing molecular parity violation. Theoretical work in the past decade has shown that parity-violating potentials in chiral molecules are much larger (typically one to two orders of magnitude) than anticipated on the basis of older theories. This makes experimental approaches toward small molecular parity-violating effects promising. The concepts and results of intramolecular dynamics derived from spectroscopy are analyzed as a sequence of symmetry breakings. We summarize the concepts of symmetry breakings (de facto and de lege) in view of parity violation in chiral molecules. The experimental schemes and the current status of spectroscopic experiments on molecular parity violation are established. We discuss the promises of detecting and accurately measuring parity-violating energy differences Delta(pv) E on the order of 10(11) J mol(1) (approximately 100 aeV) in enantiomers of chiral molecules with regard to their contribution to fundamental physics in the framework of the standard model of particle physics and more speculative future fundamental symmetry tests such as for the combined charge conjugation, parity, and time-reversal (CPT) symmetry violation.

Quantum stochastic resonance in parity violating chiral molecules

“…In this situation, C v = C (0) v in the linear response regime. Table 1 shows a short list of selected chiral molecules 10 with the orders of magnitude of their corresponding temperatures T st at which QSR would appear together with the critical temperatures T c defined in eqn (7) associated with C (0) v . Notice the different orders of magnitude of T c and T st in the cases where the tunneling splitting is much greater than e PV .…”

“…4,5 Although the weak interaction has been extensively studied and observed in atoms, 6,7 it has only been predicted in molecules. Electroweak quantum chemistry calculations predict the PVED to be between 10 À13 and 10 À21 eV [8][9][10][11] but no conclusive energy difference has been reported, for instance, in experimental spectroscopic studies of the CHBrClF molecule reaching an energy resolution of about 10 À15 eV. 12 It is however noticeable the experimental results of Wang et al 13,14 in which a chiral discriminating phase transition without conformational changes was obtained at temperature 77-300 K for D/L-alanine and valine.…”

Forbidden Vibrational Transitions in Cold Molecular Ions: Experimental Observation and Potential Applications

“…To that end, radiation sources with a smaller bandwidth as well as new non-destructive detection schemes based on quantum logic applicable to single-molecule experiments should be employed. [20] Looking even further into the future, experiments with polyatomic molecular ions could be envisioned that would allow studying the influence of the parity-violating weak interaction on chiral molecules [21] and its possible ramification on the homochirality found in biomolecules. [22] …”

An alternative route to detect parity violating energy differences through Bose–Einstein condensation of chiral molecules

“…This system has e PV E 2.5 Â 10 À14 eV, d E 5 Â 10 À17 eV and the tunneling time is B40 s (see Table 2 of ref. 13). Its subcritical density, n sc , is about 10 10 cm À3 , which is of the order of the critical densities.…”

“…This plot clearly shows the overall shoulder-type structure as well as the subcritical maximum for different chiral molecules, characterized by the splitting D. This splitting is representative of molecules such as, for example, H 2 S 2 , CHBrClF and H 2 Se 2 . 13 …”