I most uses, "an" would be the only correct article.
Interested in Language
There was an excess of men over women.
I think both 'an excess of ' and 'the excess of' would be correct here and mean almost the same thing.
'an excess of' implies that the excess could be slight, large, etc.
'the excess of' is because of the "of-phrase".
Am I right?
You said "The excess of women" refers to a specific occurrence/situation.", but look at the following quote -- isn't it talking about "a specific occurrence/situation"?
Also, as was the case in the white
population, the sex ratio among Barbadian blacks was the norm.
That is, there was an excess of women over men in both racial
groups, a pattern which emerged in the last decades of the
seventeenth century, making Barbados quite unlike other
Caribbean islands, where there was an excess of men over women
in both racial groups.