Coherent multi-electron transfer

Theoretical notions rest on electrochemical electron transfer but the novel environments have also disclosed new electron transfer phenomena. Switching or negative differential resistance, quite different from electrochemical electron transfer at semi-infinite electrode surfaces is immediately conspicuous. Coherent, multi-electron transfer in a single in situ STM event is another non-traditional electron transfer phenomenon. 

In this chapter we describe advances in the femtosecond time-resolved multiphoton photoemission spectroscopy (TR-MPP) as a method for probing electronic structure and ultrafast interfacial charge transfer dynamics of adsorbate-covered solid surfaces. The focus is on surface science-based approaches that combine ultrafast optical pump probe excitation to induce nonlinear multi-photon photoemission (MPP) from clean or adsorbate covered single crystal surfaces. The photoemitted electrons transmit spectroscopic and dynamical information, which is captured by their energy analysis in real or reciprocal space. We examine how photoelectron spectroscopy and microscopy yield information on the unoccupied molecular structure, electron transfer and relaxation processes, light induced chemical and physical transformations and the evolution of coherent single particle and collective excitations at solid surfaces. 

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