aldol addition/ condensation and IR

[sara...@gmail.com]

I am examining the IR spectrum of the product from an aldol addition/
condensation reaction, trying to determine if it is 2-benzylidene
cyclohexanone or trans-4-phenyl-3-butene-2-one.

The only difference in the molecules is what is attached to the
"styrene" group... in the first, it can be seen as a cyclohexanone
attached to a styrene, and in the second, an acetone attached to a
styrene. What would the differences be on the IR spec?

I am examining the 2 spectra on SDBS, and it seems that many of the
peaks in the 2-benzylidene cyclohexanone are broader. It also seems
that the carbonyl is shifted slightly upfield. The intensity of the
3000 region is also much more on this molecule. Can anyone help me
understand why?

Thanks