Apply glow effect to individual text character

Hello,

I would like to apply the glow effect to an individual character in a string using the range selector. The result would be that each character would momentarily 'glow' sequentially.

Its important this is done as part of an expression rather than a masked effect or otherwise.

I can obviously loop through each character but I'm stuck on how to apply an effect to that individual character that isn't within the list of useable properties.

Thanks.