IR/Raman spectra and symmetry

  • Thread starter greisen
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Main Question or Discussion Point

hi,

I am trying to interpret some data which have been calculated for IR/Raman but I don't know how to interpret them exactly. The schema says
mode \nu
1 b_u 82
1 a_g 216
2 b_g 239

I presume that the u/g are gerade/ungerade from the bonding/antibonding wave functions but how to assign these informations into stretch, bend etc. Is there a table where one can look these values up?

How to proceed any help appreciated. Thanks in advance.

Best regards,
 

Answers and Replies

hi,

I am trying to interpret some data which have been calculated for IR/Raman but I don't know how to interpret them exactly. The schema says
mode \nu
1 b_u 82
1 a_g 216
2 b_g 239

I presume that the u/g are gerade/ungerade from the bonding/antibonding wave functions but how to assign these informations into stretch, bend etc. Is there a table where one can look these values up?

How to proceed any help appreciated. Thanks in advance.

Best regards,
You have to find out the symmetry of the system and then look at the character table for that point group. The meanings of a and b etc are all in the character table and will tell you which motions (bend, stretch) are raman active and which are not.
 
76
0
hi,

A character table - is it possible to find that online or does one have to consult a certain book?
 

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