Spectroscopy Clarification Or Adding Extra Info

[Water]

Basically, a summary of what I learnt for spectroscopy thus far.. Any corrections in terms of theory or adding extra information would be appreciated, as I feel my understanding of this area is still quite vague, somewhat.


Flame Test: By seeing what color is emitted from metals, we can relate to what metal it corresponds to. Limited in metal species and can become not very accurate.

Atomic Emission Spectroscopy: Slightly more sophisticated than Flame Test, the flame's light is emitted through a slit, into a prism which divides the light into an emission spectrum. Through this, we can identify what sample it is.

The two types are based on the atoms becoming excited , and photons are released as the excited returns to ground state, which give us an indication of the light.

Atomic Absorption Spectroscopy: This is the analysis through the absorption of energy by the sample. Can only apply for metal. A wavelength of interest is passed through the sample. Through this, we can detect how much light is absorbed. This is for quantitative analysis.


UV Visible Spectroscopy, is another form of analysis. This is because some metals do not give color, however the theory applies that, with the amount of light that is absorbed and observed, with the correct wave length. We can identify , how concentrated the solution is. This solution is measured against other standard solutions.


Infrared Spectroscopy is the analysis of bending/stretching of molecules. This cannot apply to homonuclear diatomic molecules as the energy to bend the bonds, is not strong enough. This is because strength in wavelength is limited. Also, they are not dipole dipole, so either bonds are not weakened, when energy is enforced. This analysis is is much weaker than both UV Vis and AAS, as it uses a longer wavelength. Different amounts of wavelengths will be able to give an outline of the molecule being analyzed. Such as functional groups and a basic finger print.


Nuclear Magnetic Resonance Spectroscopy is the analysis of the energy required to cause a spin within the molecules. This is measured against a TMS, which acts a reference cell (Though someone can elaborate on it would be nice). Through these chemiical shifts, and peaks, numbering the different environments, we can identify the molecule and its structure.