Molecular vs. Atomic Absorption Spectroscopy

[foolishone]

Does anyone know the difference between molecular absorption spectroscopy and atomic absorption spectroscopy? I know AAS destroys the sample, but I need to know another diffference? I tried searching but can't really find anything about MAS. Is there another name for MAS?

 

Thanks,

 

fo

[Dak]

afaik, MAS is usually reffered to by the type of wavelength it's adsorbing, eg infra-red adsorption spectroscopy, UV-AS, or just electromagnetic adsorption spectroscopy, so you might want to search for terms such as those...

 

i think AAS measures the adsorption of the constituent atoms across a region of the EM spectrum, whilst MAS measures the adsorption of the molecule across a region of the EM spectrum.

 

I dont think AAS can identify substances, unless they are elements... i know it's used to identify heavy metals, but you can't, say, ID cannabis using AAS (tho i might be wrong)

[swansont]

Just to note, adsorption and absorption are two distinct processes.

[swansont]

I know AAS destroys the sample

 

I assume you mean that in order to use AAS on a sample, you have to atomize it; simply absorbing a photon isn't going to do anything to destroy the atom itself.

 

AAS is only going to involve electronic transitions, as there are no vibrational or rotational states to interrogate. It can tell you the constituent atoms but not how they were originally arranged.

[jdurg]

I assume you mean that in order to use AAS on a sample, you have to atomize it; simply absorbing a photon isn't going to do anything to destroy the atom itself.

 

AAS is only going to involve electronic transitions, as there are no vibrational or rotational states to interrogate. It can tell you the constituent atoms but not how they were originally arranged.

 

Exactly. MAS will tell you that Carbon atom 1 was bound to oxygen atom 2, while AAS will only tell you that you have two oxygen atoms and one carbon atom but not how they were arranged.