Search results for "vibration"
showing 10 items of 823 documents
Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon
2012
Raman signal is monitored after 248 nm photodissociation of formaldehyde in solid Ar at temperatures of 9–30 K. Rotational transitions J = 2 ← 0 for para-H2 fragments and J = 3 ← 1 for ortho-H2 are observed as sharp peaks at 347.2 cm−1 and 578.3 cm−1, respectively, which both are accompanied by a broader shoulder band that shows a split structure. The rovibrational spectrum of CO fragments has transitions at 2136.5 cm−1, 2138.3 cm−1, 2139.9 cm−1, and 2149 cm−1. To explain the observations, we performed adiabatic rotational potential calculations to simulate the Raman spectrum. The simulations indicate that the splitting of rotational transitions is a site effect, where H2 molecules can resi…
Differential Cross Sections and Product Rovibrational Distributions for (16)O + (32)O2 and (18)O + (36)O2 Collisions.
2015
We report rotationally resolved opacity functions, product rotational distributions, and differential cross sections for the (16)O + (16)O(16)O (v = 0,j = 1) → (16)O(16)O (v' = 0,j') + (16)O and (18)O + (18)O(18)O (v = 0,j = 1) → (18)O(18)O (v' = 0,j') + (18)O collisions calculated by a time-independent quantum mechanical method employing one of the latest potential energy surface of ozone [ Dawes ; et al. J. Chem. Phys. 2013 , 139 , 201103 ]. The results obtained for both collisional systems in the energy range 0.001-0.2 eV are examined, and interesting mass scaling effects have been discovered. The shapes of product angular distributions suggest a transition from an indirect to a direct s…
Identification of Precious Artefacts: The Sonic Imprint for Small Artefacts
2010
Identification of artworks is mainly based on a few characteristics which can be observed using non-invasive tools (sight, touch, simple instruments), the investigated properties being geometry, weight, colours, texture, etc. Nowadays, technology allows reproducing all these characteristics to such an extent that even expert conservators can be deceived: in particular at the present time even the geometry of an artwork can be easily reproduced with the help of laser scanner analysis and with a rapid prototyping machine or a computer numerical control (CNC) milling machine. We propose a new tool, the Sonic Imprint, producing a code capable of identifying a rigid artefact from its vibrational…
Electronic and vibrational properties of meso-tetraphenylporphyrin on silver substrates.
2014
The electronic and vibrational properties of meso-tetraphenylporphyrin (mtpp) on silver substrates are investigated using UV–vis and surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Whereas the vibrational signatures associated with the tetrapyrrole backbone exhibit minor variations throughout sequences of consecutively recorded SERRS spectra, the C═C stretching vibrational modes localized on the meso-phenyl moieties of mtpp exhibit noticeable intensity fluctuations, masked in the average SERRS response. We attribute the observed vibrational-state-specific blinking events to conformational changes in mtpp, namely, torsional flexibility which mediates the coupling between th…
Robotic face milling path correction and vibration reduction
2015
In this paper the developed method for off-line compensation of tool deflections and vibration reduction when milling aluminum with an industrial robot is presented. The efficiency of this approach is verified with high precision measurements of deflections using a laser tracker. The compensation method is based on the static milling process model which can predict the mean value components of the tool forces and the passive damping system mounted on the spindle to reduce vibrations. With a process model such as the one presented in this paper and estimates of the robot's joint stiffness values, the tool path can be adjusted to counteract deflections of the tool during milling operations. T…
Contribution of vibrational modalities for navigation in virtual environments
2016
The virtual environment navigation may induces the simulator sickness depending on conditions and user’s profile. The potential virtual reality multimodality may provide solutions to these problems while improving the sense of presence. In this context, the objective of this research is to determine what is the impact of vibrational modalities for navigation in virtual environments on the simulation.A taxonomy of navigation methods is proposed. It results in 4 types, specific egocentric, specific exocentric, abstract egocentric and abstract exocentric. First we simulate rumble strip vibrations during a driving simulation. The experimentation exposed that these vibrations make driver more aw…
Complexes of HXeY with HX (Y, X = F, Cl, Br, I) : Symmetry-Adapted Perturbation Theory Study and Anharmonic Vibrational Analysis
2023
A comprehensive analysis of the intermolecular interaction energy and anharmonic vibrations of 41 structures of the HXeY· · · HX (X, Y = F, Cl, Br, I) family of noble-gas-compound complexes for all possible combinations of Y and X was conducted. New structures were identified, and their interaction energies were studied by means of symmetry-adapted perturbation theory, up to secondorder corrections: this provided insight into the physical nature of the interaction in the complexes. The energy components were discussed, in connection to anharmonic frequency analysis. The results show that the induction and dispersion corrections were the main driving forces of the interaction, and that their…
Collisional shifting and broadening coefficients for the rovibrational anisotropic S(J) lines of nitrogen studied by inverse Raman spectroscopy
1996
0377-0486; Line shifting and broadening coefficients of the anisotropic S(J) lines (v = 0, J --> v = 1, J + 2) of the nitrogen molecule were measured at room temperature using high-resolution stimulated Raman spectroscopy. A rotational quantum number dependence of the S(J) line shifts was observed. In order to avoid an asymmetry of experimental origin, a suitable theoretical profile was fitted to the experimental lineshapes. This study allows the testing of the theoretical methods for calculating the line broadening coefficients in anisotropic Raman scattering, which have already been used in the analysis of infrared absorption data. The behaviour of the modified sum rule and the RPA (rando…
<title>Scanning probe microscopy of nanocrystalline iridium oxide thin films</title>
2003
Structural investigations of nanocrystalline iridium oxide thin films, prepared by dc magnetron sputtering technique were performed by scanning probe microscopy (SPM). SPM studies, using both atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), indicate that the thin films are composed of grains with a size of about 20-50 nm. Fine crystallinity and small RMS microroughness of the films, being well below 2 nm, make iridium oxide thin films promising candidates for nanolithographic applications. The possibility to perform nanolithograhpic processes at a scale of less than 150 nm was successfully examined in AFM and STM modes.© (2003) COPYRIGHT SPIE--The International Societ…
Raman study of crystals
1997
In this work we present a polarized Raman study of single crystals for several values of the concentration made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range . In each of the spectra we found two bands at about 590 and , probably associated with the existence of structures in the solid solutions.