According to Kasha, H-type aggregates are blue shifted while J-type aggregates are red shifted from the monomer. This implies if both types of aggregations coexist in a polymer the excitation energy of H-type has to be greater than that of J-type. However, some people assign the opposite.
@Hugh
Thank you for your response. Here are two examples.
Figure 2c and 5d of the paper by Shu Hu et al, on 'Effect of Thermal Annealing on Conformation of MEH-PPV Chains in Polymer Matrix: Coexistence of H- and J-Aggregates' and Table 2 of M. Guesmi's paper, 'Impact of alkoxy side chains on morphology and excitonic coupling in PPE-PPV copolymer thin films'.
Figure 2c of Shu Hu et al. is an emission profile, as is the data of Table 2 of M. Guesmi's paper.
Yes they are both emission profiles.
My intention was not to ask only for absorbance, but for emission too.
I think Kasha's principle applies for emissions too.
In that case I can not justify the assignments those people do.
The relative position of the emission peaks depends on the relative amounts of excited state relaxation, leading to Stoke's shift of the emission.
Yes!
And H aggregates undergo more excited state relaxations than J's leading to larger Stokes' shift of H-aggregates.
This may imply emission peaks of H-type are blue-shifted than J-types.
So, I still can not justify the assignment those people do.
Or that they are more red shifted?
Article Fluorescent J-aggregates of cyanine dyes: basic research and...
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