A vibration excitation system (VES) in a form of an active coupling is proposed, designed and manufactured. The system is equipped with a set of piezoelectric stack actuators uniformly distributed around the rotor axis and positioned parallel to each other. The actuator arrangement allows an axial displacement of the coupling halves as well as their rotation about any transverse axis. Through the application of the VES an aimed vibration excitation is realised in a co-rotating coordinate system, which enables a non-invasive and precise modal analysis of rotating components. As an example, the VES is applied for the characterisation of the structural dynamic behaviour of a generic steel rotor at different rotational speeds. The first results are promising for both stationary and rotating conditions.
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http://dx.doi.org/10.3390/s19010092 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
December 2024
Institute for Theoretical and Applied Electromagnetics RAS, Moscow 125412, Russia; Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia.
In this study, we have investigated the surface-enhanced Raman scattering (SERS) spectra of myoglobin on silver substrates with different morphology. The aim was to determine the optimal parameters of analyte and substrate preparation for obtaining of high-amplitude SERS spectra of proteins. It is shown that not only the morphology of the silver film, but also the method of analyte molecules deposition on the SERS substrate plays an important role.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden.
Vibrational polaritons are formed by strong coupling of molecular vibrations and photon modes in an optical cavity. Experiments have demonstrated that vibrational strong coupling can change molecular properties and even affect chemical reactivity. However, the interactions in a molecular ensemble are complex, and the exact mechanisms that lead to modifications are not fully understood yet.
View Article and Find Full Text PDFNanoscale Adv
December 2024
Institute of Science and Technology, TNU-University of Sciences Thai Nguyen Vietnam
This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu ions using Reisfeld's approximation. Eu-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses.
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Theoretical Chemistry Lab, Unit of Theoretical and Structural Physical Chemistry, Namur Institute of Structured Matter, University of Namur, Rue de Bruxelles, 61, Namur B-5000, Belgium.
The Doktorov's quantum algorithm has been enacted in combination with time-dependent density functional theory (TD-DFT) to simulate the vibronic structure of the UV/visible absorption spectra of the phenol and phenolate molecules. On the one hand, DFT and TD-DFT are employed with classical algorithms to calculate the ground and excited-state electronic structures as well as their vibrational frequencies and normal modes, whereas, on the other hand, quantum algorithms are employed for evaluating the vibrational transition intensities. In comparison to a previous study, , 128, 4369-4377, which demonstrated Doktorov's quantum algorithm as a proof of concept to predict the vibronic structure of ionization spectra, it is applied here to medium-size molecules with more than 30 vibrational normal modes, without accounting for Duschinsky rotations due to software limitations.
View Article and Find Full Text PDFMicromodification in bulk undoped polymethylmethacrylate (PMMA) by single focused (numerical aperture (NA) = 0.25), 1030-nm 250-fs laser pump pulses was explored by pump self-transmittance; optical, 3D-scanning confocal photoluminescence (PL); Raman micro-spectroscopy; and optical polarimetric and interferometric microscopy. Starting from the threshold pulse energy = 0.
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