Anion Photoelectron Spectroscopy and Density Functional Theory Studies of AuC _\mathitn ^-\textbf/0 ( \mathitn =3 - 8): Odd-Even Alternation in Electron Binding Energies and Structures

We measured the photoelectron spectra of AuC _n ^- ( n = 3 - 8) and conducted theoretical study on the structures and properties of AuC _n ^-/0 ( n = 3 - 8). It is found that the photoelectron spectra of AuC _n ^- exhibit odd-even alternation. The spectral features of AuC _3 ^- , AuC _5 ^- , and AuC _7 ^- are much broader than those of AuC _4 ^- , AuC _6 ^- , and AuC _8 ^- . The vertical detachment energies of AuC _3 ^- , AuC _5 ^- , and AuC _7 ^- are lower than those of AuC _4 ^- , AuC _6 ^- , and AuC _8 ^- . The most stable structures of AuC _n ^- ( n = 3 - 8) are chain structures. The most stable structures of neutral AuC _n ( n = 3 - 8) are linear structures except that those of AuC _3 and AuC _5 are slightly bent. The calculated \angle AuCC angles, Au - C bond lengths, and the charges on Au atom also show odd-even alternations, consistent with the experimental observations.