External Field Effect on Electronic and Vibrational Properties of Carotenoids

Abstract

Resonance Raman spectroscopy is one of the most popular molecular spectroscopy methods. Using this technique, carbon-carbon (CC) vibration can be well investigated and give much information on π-conjugated system. The CC vibration has a strong dependence on the π-electron band gap, which is able to be characterized by absorption spectroscopy. Electron-phonon coupling will strongly influence the Raman intensity and shows sensitivity to the surrounding environment. Through electron-phonon coupling, CC vibration can be modulated by the π-electron band gap. In this review, we present our absorption and Raman-scattering observations of all-trans-beta-carotene from different environment such as temperature, pressure, solvents, and phase transition. The relationship between π-electron band gap and CC vibration is studied. With the decreasing of the π-electron energy, the modulation on CC vibration and electron-phonon coupling is enhanced leading to spectral red-shift. This review has significant importance in understanding the resonance Raman scattering, structural properties of polyenes, and the physics behind it. The results are also valuable for the development of fine-quality photoelectric device.

Quantification of Plasma Dopamine in Depressed Patients Using Silver-Enriched Silicon Nanowires as SERS-Active Substrates

“…75,76 Furthermore, the polarizability, polarity, and other properties of the solvent can impact the induced dipole moment of the analyte molecule, thereby causing a Raman shift. 77 Actually, we observed Raman shift differences between solution states (ethanol, serum, extracted plasma) in reference to DA powder samples at 870, 1011, 1146, 1290, and 1456 cm −1 (Figure S4). These differences are likely due to varying intermolecular interactions in different solvents affecting the protonation or deprotonation of hydroxyl and amine groups of DA.…”

Enhancing the Refractive Index of Polymers with a Plant‐Based Pigment

“…We suspect that these differences arise from changes in the local electronic environment in solution and the solid state. [37] While pure BC has attractive optical properties, it is difficult to process because it is very brittle and weak, breaking into a powder with even gentle handling. We hypothesized that dispersing BC in a polymer matrix could maintain a high index of refraction while improving its processibility.…”

“…We suspect that these differences arise from changes in the local electronic environment in solution and the solid state. [ 37 ]…”

Study of Microplastics and Inorganic Contaminants in Mussels from the Montenegrin Coast, Adriatic Sea

“…Some spectral features are common to all the acquired spectra, such as the peaks around 2900 cm −1 , ascribed to C-H vibrations, and the intense contribution due to the underlying silicon substrate at 521 cm −1 . However, certain specific bands, indicated by the arrows, appear only in the Orahovac sample and they are attributed to the presence of carotenoids [37]. In fact, the most intense band (v 1 ) at 1520 cm −1 comes from C=C vibrations of the polyene chain, which depends on π-electron conjugation and molecular configuration, while the v 2 band at about 1155 cm −1 is associated with C-C stretching coupled with C-C in-plane bending modes [38].…”