![]() ![]() According to Rudman and Post, the monoclinic is the stable form below 225 K and, thus, should be considered to be present at the INS experiment conditions (ca. ![]() In particular, DFT calculations-either periodic or discrete-were found to be highly efficient in predicting the eigenvectors (atomic displacements) for the vibrational normal modes and, thus, to simulate the corresponding INS spectrum (see, e.g., the above-mentioned work from some of the authors ).Ĭarbon tetrachloride is known to form three solid phases on cooling from the liquid at ambient pressure: a face-centered cubic phase Iα, a rhombohedral phase Iβ, and a monoclinic phase II. While the former is an invariant experimental value, the latter is accessible from standard vibrational frequency calculations. The INS intensity of a band associated with a given vibrational mode is proportional to the neutron scattering cross-section of the moving nuclei and to the amplitude of nuclei displacement. In addition, INS spectroscopy is particularly suitable for the computational spectroscopy approach. Large amplitude/low wavenumber modes, including lattice modes, usually problematic for optical spectroscopy, tend to yield intense bands in INS spectra. Due to the absence of selection rules, all vibrational modes are potentially observable through INS spectroscopy. INS spectroscopy provides a unique assessment of the structural dynamics that is not amenable from its optical counterparts, infrared and Raman spectroscopies. ![]()
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