Microwave chirality discrimination in enantiomeric liquids

Abstract

Chirality discrimination is of a fundamental interest in biology, chemistry, and metamaterial studies. In optics, near-field plasmon-resonance spectroscopy with superchiral probing fields is effectively applicable for analyses of large biomolecules with chiral properties. We show possibility for microwave near-field chirality discrimination analysis based on magnon-resonance spectroscopy. Newly developed capabilities in microwave sensing using magnetoelectric (ME) probing fields originated from multiresonance magnetic-dipolar-mode (MDM) oscillations in quasi-2D yttrium-irongarnet (YIG) disks, provide a potential for unprecedented measurements of chemical and biological objects. We report on microwave near-field chirality discrimination for aqueous D-and L-glucose solutions. The shown ME-field sensing is addressed to microwave biomedical diagnostics and pathogen detection and to deepening our understanding of microwave-biosystem interactions. It can be also important for an analysis and design of microwave chiral metamaterials.Many molecules in chemistry and biology are chiral. Biologically active molecules in amino acids (the building blocks of proteins) and sugars are chiral molecules. Chiral discrimination in a mixture of chiral molecules is among the most important and difficult tasks in biophysics and chemistry. In this connection, development of a technique that offers improved chiral analysis and better understanding of interactions of electromagnetic fields with chiral materials remains an important goal. Traditional chiroptical spectroscopy arises from the effect of interference between the electric-dipole transition moment and the weak magnetic-dipole transition moment that is detected when a chiral molecule is irradiated with alternating right-or left-circularly polarized light [1 -3]. For localized (subwavelength) chiroptical biosensing, special plasmonic structures with left-and right-handed superchiral probing fields are effectively used [4 -6].The measured forms of chiroptical intensity are inversely proportional to the wavelength of the probing radiation. That is why use of microwave radiation to detect chirality was considered as a non-solvable problem. Surprisingly, a new microwave technique based on chirality-sensitive three-wave mixing to identify the enantiomers of chiral molecules, was demonstrated in Ref. [7]. This technique departs from traditional (optical) electromagnetic methods for detecting and identifying the handedness of molecules. Because it does not depend on a weak magnetic-dipole transition moment, the chiral signal is nearly as large as that of the applied microwaves. This conceptually new method to detect chirality is applicable, however, to cold gas-phase molecules. Based on the three-wave technique for molecules sampled in the gas phase [7], one cannot study handedness properties of liquid structures in microwaves, attractive for biological applications. Microwaves are attractive for biological applications because of their sensitivity to water and dielectric contrast. As a ...

Ultrafast chirality: the road to efficient chiral measurements

“…88 It has been recently brought to our attention that interesting opportunities for efficient enantiodiscrimination (although not directly related to electric-dipole approximation methods) arise from the possibility of applying magneto-electric probing fields to near-field microwave spectroscopy. 149 3.4 Enantio-sensitive non-linear wave-mixing PXCD and EMWS are not the only two relatives in the family of enantio-sensitive phenomena which occur in the electricdipole approximation and follow Rule 1. Although PXCD and EMWS are resonant processes, and oscillations take place in the absence of the driving field, the pseudoscalar g can loosely be interpreted as a second order susceptibility w (2) .…”

Magnetoelectric Near Fields

“…The frequency  is defined based on both, spin and orbital, momentums of the fields of MDM oscillations. It was shown experimentally that the chiral structure of near-field ME provides the potential for microwave chirality discrimination in chemical and biological objects [103].…”

Quantization of magnetoelectric fields

“…In Ref. [97], we have experimental observation of microwave chirality discrimination in liquid samples due to MDM eigenstate chirality. There is an evident correspondence between topological edge modes of MDM oscillations and "external" chirality of inserted objects.…”

“…Numerous studies of these properties for MDM structures, both numerical and experimental, are shown in Refs. [35,65,96,97].…”