Natalia Drichko

BEDT-TTF-based organic conductors host a number of ground states, tuned by electron repulsion. Knowledge of the charge distribution on the molecular sites in these materials is key to understanding the origin of different ground states. We survey and discuss the C=C stretching modes in BEDT-TTF based molecular conductors, which are extremely crucial in the characterization of charge-ordered insulators and are recently linked to superconductivity in some compounds. Focusing on the known examples of BEDT-TTF+0.5 salts, we analyze the reliability of the C=C stretching modes for the determination of charge ordering and absolute site charge. Considering the charge-ordered states, a prominent shift in frequency of 141 cm−1 per elementary charge e for ν27(b1u) and 98 cm−1/e for ν2(ag) can be clearly observed; however, the distribution resulting from different compounds spans over 20 cm−1. For nominal BEDT-TTF+0.5 compounds, the distribution of the resonance also extends around 20 cm−1, yielding an unexpectedly large uncertainty of Δρ ≈ (±0.04)e, which is presumably due to the influence of small differences in the structure. This highlights the limitations of charge–frequency relations to detect small deviations in absolute charge values on molecular lattice sites and emphasizes the use of the relations to estimate charge-ordering, rather than absolute site charge.

Previously, we reported that microplastic volatile organic compounds are present within the Chrysaora chesapeakei of Chesapeake Bay, MD. In this study, we report the presence of contaminants of emerging concern (CECs) on the hydrophobic surface of microplastic (MP) particles extracted from the C. chesapeakei, detected by Raman spectroscopy and identified by Wiley’s KnowItAll Software with IR & Raman Spectral Libraries. C. chesapeakei encounters various microplastics and emerging contaminants as it floats through the depths of the Patuxent River water column. This study identifies subsuming CECs found directly on microplastics from within C. chesapeakei in the wild using Raman spectroscopy. Among the extracted microplastics, some of the emerging contaminants found on the different microplastics were pesticides, pharmaceuticals, minerals, food derivatives, wastewater treatment chemicals, hormones, and recreational drugs. Our results represent the first of such findings in C. chesapeakei, obtained directly from the field, and indicate C. chesapeakei’s relationship with microplastics, with this species serving as a vector of emerging contaminants through the marine food web. This paper further illustrates a relationship between different types of plastics that attract dissimilar types of emerging pollutants in the same surrounding environmental conditions, underscoring the urgent need for further research to fully understand and mitigate the risks that MPs coexist with contaminants.

Weyl semimetals are characterized by an electronic structure with linearly dispersed nodes and distinguished chirality, protected by broken inversion or time reversal symmetry. The intercalated transition metal dichalcogenide V$_{1/3}$NbS$_2$ is proposed as a Weyl semimetal. In this study, we report polarization-resolved magnetic and electronic Raman scattering of this material, probing both the magnetic order and the electronic structure. The electronic scattering reveals a linear with frequency continuum of excitations, as the signature of electronic transitions within the proposed Weyl nodes in a two-dimensional electronic structure. Additionally, two-magnon excitations of V moments are observed near 15 meV in the magnetically ordered phase below 50 K. These excitations are well reproduced by calculations based on the Fleury-Loudon theory using spin wave exchange parameters derived from the neutron scattering data of this material and confirm the antiferromagnetic character of the order. These magnetic and electronic scattering, observed in the same spectra, provide independent spectroscopic evidence for a collinear antiferromagnetic Weyl semimetal state in V$_{1/3}$NbS$_2$.