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Showing 1 - 10 of 33 results
• Updated 2 months ago - 6,599 words
Since there is a field distribution of E o at the surface of M o, it can be said that there is a field distribution at the surface of M 1 . Since there will be a change in size of the field this means that the electromagnetic wave will have change in amplitude by ρ 0 *ρ 1 and a phase factor of $$e^-jk2d$$, creating additional fields. If λ is the wavelength of the laser light, a is the radius of the beam, and f is the focal length of the lens, then the radius of the region is
http://chemwiki.ucdavis.edu/Analytical_Chemistry/Instrumental_Analysis/Lasers
• Updated 2 months ago - 2,029 words
Figure 1, above, starts with a negative ion sputter source, which commonly consists of a stream of Cesium ions (Cs + ) with energies of 2-3 keV focused on the surface of a solid sample in order to transfer enough energy to the target material to produce free atoms and ions of the sample material.
http://chemwiki.ucdavis.edu/Analytical_Chemistry/Instrumental_Analysis/Mass_Spectrometry/Accelerator_Mass_Spectroscopy
• Updated 2 months ago - 3,060 words
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…
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Raman_Spectroscopy/Raman%3A_Theory
• Updated 2 months ago - 2,745 words
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 + …
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Combination_Bands%2C_Overtones_and_Fermi_Resonances
• Updated 2 months ago - 1,152 words
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.
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Magnetic_Resonance_Spectroscopies/Electron_Paramagnetic_Resonance/Parallel_Mode_EPR%3A_Theory_and_Application
• Updated 2 months ago - 2,247 words
3) Chemical shift of each protons is predicted by 1 H chemical shift ranges (Fig.1): chemical shift of methyl groups (H a ) : 1-2 ppm (?H a =1.1 ppm); chemical shift of -CH- groups (H b ) moves to downfield due to effect on aldehyde groups:2-3ppm ( ?H b =2.4 ppm); chemical shift of aldehyde groups (H c ):9-10 ppm (?H c =9.6 ppm)
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Magnetic_Resonance_Spectroscopies/Nuclear_Magnetic_Resonance/NMR%3A_Experimental/NMR%3A_Interpretation
• Updated 2 months ago - 7,849 words
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.
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Fundamentals/Selection_rules_and_transition_moment_integral
• Updated 2 months ago - 4,455 words
basic Aniline Fluorescence of certain compounds have been used a detection of end points in acid-base titrations.An example of this type of fluorescence seen in compound as a function of pH is the phenolic form of 1-naphthol-4-sulfonic acid.This compound is not detectable with the eye because it occurs in the ultraviolet region, but with an addition of a base, it becomes converted to a phenolate ion, the emission band shifts to the visible wavelength where it can be visually seen.Acid dissociat…
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Electronic_Spectroscopy%3A_Theory
• Updated 2 months ago - 439 words
Sodium azide is used as a source of azide anion which is a strong nucleophile that readily displaces suitable leaving groups. For a detailed description of how to quench sodium azide see the Health and Safety provided by Northeastern University: http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/. It can be quenched by nitrous acid With stirring add a 20% solution of sodium nitrite containing 1.5 g of sodium nitrite per gram of azide
http://chemwiki.ucdavis.edu/VV_Lab_Techniques/Reagent_Specific_Hazards/Sodium_Azide
• Updated 2 months ago - 1,688 words
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.
http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Magnetic_Resonance_Spectroscopies/Electron_Paramagnetic_Resonance/EPR%3A_Interpretation
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