Rayleigh scattering comes from the dipole oscillating at ω 0 induced in the molecule by the electric field of the incident radiation at frequency ω 0 . Raman scattering arises from the dipole moment oscillating at ω 0 ±ω k produced by the modulation of dipole oscillating at ω 0 with molecular vibration at frequency ω k . In other words, the frequencies we observe in Raman scattering are beat frequencies of the radiation frequency ω 0 and the molecular vibrational frequency ω k . Quantum mechan…
Because the vibrations have nearly the same frequency, the interaction will be affected if one mode undergoes a frequency shift from deuteration or a solvent effect while the other does not.The molecule most studied for this type of resonance (even what Fermi himself used to explain this phenomena), is carbon dioxide, CO 2 . The three fundamental vibrations are v 1 = 1337 cm -1 , v 2 =667 cm -1 , v 3 =2349 cm -1 . The first overtone of v 2 is v 1 + 2v 2 with symmetries σ g + and (σ g + + δ g + …
B is the magnetic field vector, is the Bohr magneton, S z is the z projection of the spin, and is the angle of the applied magnetic field with respect to the symmetry axis of the system in the zx-plane. We have shown that, by taking linear combinations of the and states that show no transitions, we can construct a description of the system that accounts for the transitions observed in the parallel mode EPR spectra of integer spin systems.
The electronic-state configurations for molecules can be described by the primary quantum number n, the angular momentum quantum number Λ, the spin quantum number S, which remains a good quantum number, the quantum number Σ (S, S-1, ..., -S), and the projection of the total angular momentum quantum number onto the molecular symmetry axis Ω, which can be derived as Ω=Λ+Σ.
Thus, the magnetic field is on the x-axis of EPR spectrum; dχ″/dB, the derivative of the imaginary part of the molecular magnetic susceptibility with respect to the external static magnetic field in arbitrary units is on the y-axis. This value contains the chemical information that lies in the interaction between the electron and the electronic structure of the molecule, one can simply take the value of g = g e + Δg as a fingerprint of the molecule.
“RS is similar to IR in that they have regions that are useful for functional group detection and fingerprint regions that permit the identification of specific compounds.” While from the different selection rules of Raman Spectroscopy and IR, we can get the Mutual Exclusion rule , which says that for a molecule with a center of symmetry, no mode can be both IR and Raman Spectroscopy active.
In certain XANES spectra, the rising absorption edge might lead to a sharp intense peak referred as “white line”. The reason is that in the past, X-ray absorption spectra were recorded using photographic plates, and the strong absorption of certain wavelength leads to an unexposed band on the photographic plates which after develops in negative, appear as a white vertical stripe, hence the term “white line”.
Through a careful study of multiple model compounds of known oxidation states and spin configurations, from Ni(I), to low- and high-spin Ni(III) up to Ni(IV), a relationship is derived between the position of the L 3 edge and the ratio of the integrals of the L 3 and L 2 edges.
This rule states that the absorption coefficient is proportional to the square of the transition moment integral, or |<i|H|f>| 2 , where i is the unaffected core energy level before it interferes with the neighboring atoms, H is the interaction, and f is the final state in which the core energy level has been affected and a photoelectron has been ejected.