10.1021/acs.jpcc.6b04955.s001 Tsutomu Ohta Tsutomu Ohta Masahiro Shibuta Masahiro Shibuta Hironori Tsunoyama Hironori Tsunoyama Toyoaki Eguchi Toyoaki Eguchi Atsushi Nakajima Atsushi Nakajima Charge Transfer Complexation of Ta-Encapsulating Ta@Si<sub>16</sub> Superatom with C<sub>60</sub> American Chemical Society 2016 superatomic CT XPS results UPS measurements superatomic charge transfer building block Ta C 60 molecule 720 K C 60 fullerene film heat treatment chemical states C 60 charge Transfer Complexation oxygen exposure ambient oxygen photoelectron spectroscopies chemical robustness 2016-07-08 13:56:01 Journal contribution https://acs.figshare.com/articles/journal_contribution/Charge_Transfer_Complexation_of_Ta-Encapsulating_Ta_Si_sub_16_sub_Superatom_with_C_sub_60_sub_/3474833 The tantalum-encapsulating Si<sub>16</sub> cage nanocluster superatom (Ta@Si<sub>16</sub>) has been a promising candidate for a building block of nanocluster-based functional materials. Its chemical states of Ta@Si<sub>16</sub> deposited on an electron acceptable C<sub>60</sub> fullerene film were evaluated by X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS, respectively). XPS results for Si, Ta, and C showed that Ta@Si<sub>16</sub> combines with a single C<sub>60</sub> molecule to form the superatomic charge transfer (CT) complex, (Ta@Si<sub>16</sub>)<sup>+</sup>C<sub>60</sub><sup>–</sup>. The high thermal and chemical robustness of the superatomic CT complex has been revealed by the XPS and UPS measurements conducted before and after heat treatment and oxygen exposure. Even when heated to 720 K or subjected to ambient oxygen, Ta@Si<sub>16</sub> retained its original framework, forming oxides of Ta@Si<sub>16</sub> superatom.