The　ground-state　electronic/geometrical　structures　ofthe　threeclassical　isomers　C　(　s　)(15)-C-84,　C　(2)(13)-C-84,　and　C　(2)(8)-C-84　as　well　as　the　correspondingembedded　derivatives　U@C　(　s　)(15)-C-84,　YCN@C　(2)(13)-C-84,　and　U@C　(2)(8)-C-84　havebeen　calculated　at　the　density　functional　theory　(DFT)　level.　Then,the　isomers　of　C-84　were　theoretically　identified　by　X-rayphotoelectron　spectroscopy　(XPS)　and　near　X-ray　absorption　fine-structurespectroscopy　(NEXAFS).　The　spectral　components　of　total　spectra　forcarbon　atoms　in　various　local　environments　have　been　investigated.The　ultraviolet-visible　(UV-vis)　absorption　spectroscopiesof　U@C　(　s　)(15)-C-84,　YCN@C　(2)(13)-C-84,　and　U@C　(2)(8)-C-84　have　also　been　performedutilizing　time-dependent　(TD)　DFT　calculations.　The　UV-visspectra　are　in　good　agreement　with　the　experimental　results.　Thesespectra　provide　an　effective　method　for　the　identification　of　isomers.The　results　of　this　study　can　offer　useful　data　for　further　experimentaland　theoretical　studies　using　X-ray　and　UV-vis　spectroscopymethods　on　freshly　synthesized　fullerene　isomers　and　their　derivatives.