Baopeng Cao

Tunable Field-Effect Transistor Device with Metallofullerene Nanopeapods

A fine tuning of the band gap of single-wall carbon nanotubes (SWNTs) has been achieved by filling various types of endohedral metallofullerenes into the SWNTs, the so-called nanopeapods. We report various electronic transport properties of fullerene peapods used as the channels of field-effect transistors (FETs) and demonstrate that the metallofullerene peapods can provide the tunable band gaps of the FET channels depending on the type of metallofullerene inserted in the SWNTs. All of the metallofullerene peapods FETs exhibit p- and n-type, the so-called ambipolar carrier transportation by variable gate bias. The ranges of the off state regions of the FET fabricated highly sensitivity with respect to the amount of charge transfer in metallofullerenes, which results in band-gap engineering. Metallofullerene peapods can be used to manipulate the electronic structure of SWNTs in nanometer scale. In such a highly functionalized SWNT, metallofullerene peapods, might be a key material for fabricating and developing sophisticated electronic devices in the future.

Determining C2 binding energies from KERDs for C80+ and C82+ fullerenes and their endohedrals

Abstract Kinetic Energy Release Distributions (KERDs) have been measured for the C2 evaporation from a series of fullerenes including C80+ and its endohedral compounds, Sc3N@C80+ and Ti2@C80+. We have employed Finite Heat Bath Theory (FHBT) to analyze the measured KERDs and to deduce the C2 binding energies. We re-evaluated previously measured binding energies for C82+, La@C82+, and Tb@C82+ in the light of recent findings that fragmentation of fullerene ions proceeds via a very loose transition state. This procedure demonstrates a substantial increase in the binding energy on going from C82+, to La@C82+ & Tb@C82+. The KERDs for all three ions, C80+, Sc3N@C80+, and Ti2@C80+ are nearly overlapping and the C2 binding energies are equal within experimental error. The binding energy deduced for C80+ is surprisingly high. C82+ on the other hand has nearly the same stability as C78+. These results indicate that C80 is a magic number. The results will be discussed in the light of proposed structures for the various compounds and the reliability of data deduced from KERDs.

Ultraviolet Photoelectron Spectroscopy of Two Titanium Metal Atoms Encapsulated Metallofullerenes, Ti2@C80 and Ti2@C84

Abstract Ultraviolet photoelectron spectra (UPS) of Ti2@C80 (mixture of two isomers) and two Ti2@C84 isomers excited by synchrotron radiation light source are presented. The spectra of Ti2@C80 are complicated compared with those of other metallofullerenes, which is considered with an aid of molecular orbital (MO) calculation. The photoelectron spectra of two Ti2@C84 isomers are fairly analogous with each other and show less structure than that of Sc2@C84. This suggests that the symmetry of two isomers differs from D 2d symmetry of Sc2@C84.