States determined by photoelectron spectroscopy in the perchlorate and perrhenate of TMTSF

Abstract

The photoelectron spectroscopic binding energies of Se 3d_5/2, O 1s, and Cl 2p_3/2 or Re 4f_7/2 have been measured in tetralmethyltetraselenafulvalenium (TMTSF) perchlorate and perrhenate, tetrabutylammonium perchlorate and perrhenate, and potassium perchlorate and perrhenate. It has been found that the binding energies of Se 3d_5/2 are the same in the perchlorate and the perrhenate even though the spectrum is more asymmetrically broadened in the perrhenate. The binding energy of O 1s depends on the cation and on the central atom in the anion. In the organic perrhenates it is at 530.96 eV, whereas in the perchlorates it is at 532.08 eV. In the potassium salts the O 1s binding energies differ by 1.89 eV in the perchlorate and the perrhenate. The binding energies of Cl 2p_3/2 and Re 4f_7/2 differ by 0.84 and zero respectively from those in the potassium salts. The energetic differences among the values for O 1s indicate the extent to which the electronic structure of the TMTSF salts are determined by the electronic structure of the anions. The difference in binding energies between the TMTSF perchlorate and perrhenate is such that the application of pressure to the perrhenate should transfer electrons to the cation and presumably to the conduction band.