Investigating local field tuning Fermi resonance of CS by Raman spectroscopy and DFT calculations.

In the spectroscopic study of polyatomic molecules, Fermi resonance (FR) is a vibrational coupling and energy transfer phenomenon that widely exists intra- and intermolecular. In particular, the FR coupling between the fundamental mode ν and the doubling mode 2ν of the CS molecule has attracted extensive research. In this work, we investigate the effect of local field on tuning the FR of CS.

Stoichiometric Ternary Superhydride LaBeH_{8} as a New Template for High-Temperature Superconductivity at 110 K under 80 GPa.

The search for high-temperature superconducting superhydrides has recently moved into a new phase by going beyond extensively probed binary compounds and focusing on ternary ones with vastly expanded material types and configurations for property optimization. Theoretical and experimental works have revealed promising ternary compounds that superconduct at or above room temperature, but it remains a pressing challenge to synthesize stoichiometric ternary compounds with a well-resolved crystal structure that can host high-temperature superconductivity at submegabar pressures. Here, we report on the successful synthesis of ternary LaBeH_{8} obtained via compression in a diamond anvil cell under 110-130 GPa.

Pressure-induced Fermi resonance between fundamental modes in α-Hydroquinone.

Fermi resonance (FR), a prevalent phenomenon in molecules, has an important effect in spectrum analysis. As an effective way to change the molecular structure and tune symmetry, high-pressure techniques can often induce FR. Hydroquinone (HQ) is a hydrogen-bonded crystal that tends to form a solid inclusion compound with a suitable guest and has wide applications.

Tuning the Fermi resonance of pyridine using ethanol molecules.

The Fermi resonance (FR) phenomenon is prevalent in infrared and Raman spectroscopy, and it can be observed in a variety of molecules. In particular, pyridine is a compound that has two Fermi doublets: ν ∼ ν and ν + ν ∼ ν. To analyze the effect of environmental changes on the FR, this study first investigated the Raman spectra of pyridine mixed with ethanol at different concentrations.

Giant enhancement of superconducting critical temperature in substitutional alloy (La,Ce)H.

A sharp focus of current research on superconducting superhydrides is to raise their critical temperature T at moderate pressures. Here, we report a discovery of giant enhancement of T in CeH obtained via random substitution of half Ce by La, leading to equal-atomic (La,Ce)H alloy stabilized by maximum configurational entropy, containing the LaH unit that is unstable in pure compound form. The synthesized (La,Ce)H alloy exhibits T of 148-178 K in the pressure range of 97-172 GPa, representing up to 80% enhancement of T compared to pure CeH and showcasing the highest T at sub-megabar pressure among the known superhydrides.

Fluorescence-enhanced second harmonic normal Raman scattering in β-carotene.

β-carotene, an important biomolecule from the carotenoid family, plays a vital role in biosystem, the characteristic features of electronic and vibrational spectra will shed light on its photophysical properties. Here, in-situ high pressure Raman spectra of β-carotene are measured up to 26 GPa. Two possible phase transitions are identified at about 7 GPa and 14 GPa, respectively, through analysis of the frequency-pressure relationships.