An algebraic model of Boson realization is proposed to study the vibrational spectra of a tetrahedral molecule, where ten sets of boson creation and annihilation operators are used to construct the Hamiltonian with T d symmetry. There are two schemes in our model. The first scheme provides an eight-parameter fit to the published experimental vibrational eigenvalues of methane with a root-meansquare deviation 11.61 cm −1 . The second scheme, where the bending oscillators are assumed to be harmonic and the interactions between the bending vibrations are neglected, provides a five-parameter fit with a root-mean-square deviation 12.42 cm −1 . * email address: MAZQ@BEPC3.IHEP.AC.CN
The adsorption of aniline on a silver mirror was studied by surface-enhanced Raman scattering (SERS) spectroscopy and density functional theory (DFT) calculation methods. The normal Raman and SERS spectra of pure aniline liquid and its solutions were recorded by a micro-Raman spectrometer with excitation at 514.5 nm. Orientation of the aniline molecule adsorbed on the Ag mirror is discussed. The results indicate that pure aniline is adsorbed on the surface of the Ag mirror with a tilted orientation. The conformer with the nitrogen atom interacting with the metal surface would be dominant. DFT calculations further confirm the experimental results that charge transfer (CT) takes place from the highest occupied molecular orbital(HOMO) of aniline to the singly occupied molecular orbital (SOMO) of the silver surface. In this paper, the frontier molecular orbital theory has been successfully used to explore the interaction between the aniline molecule and the silver surface.
Morpholine is a typical six-membered saturated heterocycle with the molecular formula HN(CH 2 CH 2 ) 2 O. In this work, the conformations of Morpholine in liquid and adsorbed on the surface of gold nanoparticles were studied by means of Raman spectroscopy and theoretical calculations. Ab initio calculations indicate that the energy of the chair conformers of Morpholine is ca. 7.5 kcal/mol lower than the skewboat conformers, which implies that the chair conformers would be favorable in liquid Morpholine. Comparison of the observed Raman spectra of liquid Morpholine, its solution, and the predicted spectra of the chair conformers (equatorial and axial) revealed that both of the chair conformers coexist in its liquid, and the content of the equatorialchair conformer may reduce in the solution. Considering the concentration-dependent Surface-Enhanced Raman Scattering (SERS) spectral profile, the surface selection rule, and the theoretical calculations, it has been inferred that at higher concentrations Morpholine is vertically chemisorbed on gold nanoparticles through the N atom of the ring, and the dominant conformation adsorbed is the axial-chair conformer. However, at the dilute concentrations, Morpholine is gradually flatly chemisorbed on the gold nanoparticles through the N atom, and the Morpholine may be deprotonated. Furthermore, the predicted spectra agree with the experimental ones very well, which confirms the results above.
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