I am looking at a paper that takes about thermally excited holes in relation to photocatalytic destruction, another paper with the same substance (TiO2) talks about decomposition of polycarbonates with the same method (thermally excited holes). I'm a little rusty on this topic. Please could someone explain in layman's terms what thermally excited holes are and how they would aid in a decomposition process? Any suggestions would be appreciated. Extracts from abstracts below. Thanks for any help.