For molecules without a center of symmetry, each vibrational mode may be IR active, Raman active, both, or neither.
32.
The frequency of the vibrational modes depends on the speed of sound in air, which varies with air density.
33.
Mass spectrometry detects the difference in an isotope's mass, while infrared spectroscopy detects the difference in the isotope's vibrational modes.
34.
The fraction of molecules occupying a given vibrational mode at a given temperature can be calculated using the Boltzmann distribution.
35.
The vibrational modes are restricted to part of the substrate and are thus not fully delocalized, unlike phonon vibrational modes.
36.
The vibrational modes are restricted to part of the substrate and are thus not fully delocalized, unlike phonon vibrational modes.
37.
For example, vibrational modes in a crystal, known as phonons, are associated with slow density fluctuations of the crystal's atoms.
38.
Here we can think of the Debye energy as the maximum energy associated with the vibrational modes of the lattice.
39.
When tuned near an electronic transition ( resonance ), the vibrational modes associated with that transition exhibit increased Raman scattering intensity.
40.
Raman active fibers, such as aramid and carbon, have vibrational modes that show a shift in Raman frequency with applied stress.
