Quantum dynamics of laser-induced desorption from metal and semiconductor surfaces, and related phenomena

Abstract

Recent progress towards a quantum theory of laser-induced desorption and related phenomena is reviewed, for specific examples. These comprise the photodesorption of NO from Pt(111), the scanning tunnelling microscope and laser-induced desorption and switching of H at Si(100), and the electron stimulated desorption and dissociation of CO at Ru(0001). The theoretical methods used for nuclear dynamics range from open-system density matrix theory over nonadiabatically coupled multi-state models to electron–nuclear wavepackets. Also, aspects of time-dependent spectroscopy to probe ultrafast nonadiabatic processes at surfaces will be considered for the example of two-photon photoemission of solvated electrons in ice layers on Cu(111).

Femtosecond-laser-driven molecular dynamics on surfaces: Photodesorption of molecular oxygen from Ag(110)

“…Within a good approximation, a linear increase with the laser fluence of the vibrational and translational energies of the desorbed molecules is observed. This is considered to be one of the hallmarks of DIMET [5]. Finally, it is worth noting that we also observe few dissociation events for molecules initially adsorbed in the H110 well.…”

“…Laser driven photochemistry has proven to be a useful tool for promoting reactions at surfaces or even as a way to open new reaction channels not accessible by thermal activation [1][2][3][4][5]. In particular, one important reaction is the photodesorption of a molecule from a metal surface.…”

Charge transmission through single molecules: Effects of nonequilibrium molecular vibrations and photoinduced transitions

“…The latter mechanism is discussed for many years in the field dealing with photo-desorption of molecules attached to metal surfaces. Here, one standardly distinguishes between desorption induced by electronic transitions (DIET) working in the low flux cw-range, and desorption induced by multiple electronic transitions (DIMET), where intensive but short (some hundred fs long) laser pulses are used (see [64] for a recent overview). For the DIMET mechanism the excited state of the metal surface is well described by an effective electron gas and an effective lattice temperatures changing in the range of some thousands of Kelvin but on a time-interval of a few ps.…”

The Role of Charge Localization in Current‐Driven Dynamics

“…While these efforts have focused on understanding the static conductivity of the molecular moiety, the importance of current‐driven dynamical events has also been recently demonstrated 1,26–31 . Coupling between the electronic states of the molecule and the continua of states present in the electrodes results in the formation of electronic resonances characterized by a finite lifetime and an energy shift.…”

“…[20][21][22][23][24][25] While these efforts have focused on understanding the static conductivity of the molecular moiety, the importance of current-driven dynamical events has also been recently demonstrated. 1, [26][27][28][29][30][31] Coupling between the electronic states of the molecule and the continua of states present in the electrodes results in the formation of electronic resonances characterized by a finite lifetime and an energy shift. Provided that these resonance states are energetically close to the Fermi level, they can provide a pathway for current transmission at low bias voltages and contribute to inelastic transport.…”