Desorption of CO from Ru(001) induced by near-infrared femtosecond laser pulses

Abstract

Irradiation of a Ru͑001͒ surface covered with CO using intense femtosecond laser pulses ͑800 nm, 130 fs͒ leads to desorption of CO with a nonlinear dependence of the yield on the absorbed fluence ͑100-380 J/m 2 ͒. Two-pulse correlation measurements reveal a response time of 20 ps ͑FWHM͒. The lack of an isotope effect together with the strong rise of the phonon temperature ͑2500 K͒ and the specific electronic structure of the adsorbate-substrate system strongly indicate that coupling to phonons is dominant. The experimental findings can be well reproduced within a friction-coupled heat bath model. Yet, pronounced dynamical cooling in desorption, found in the fluence-dependence of the translational energy, and in a non-Arrhenius behavior of the desorption probability reflect pronounced deviations from thermal equilibrium during desorption taking place on such a short time scale.

Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001)

“…This modeled transition takes place on the same time scale as the experimentally measured transition into the precursor state and supports the notion of a phonon-mediated transition into the precursor state. Although a similar transient might also be consistent with a weakly electron-mediated process [30], our AIMD simulations [13] support the involvement of substrate phonons in the transition into the precursor state. The simulations correspond to the experimental situation at delays longer than the electron-phonon equilibration time of…”

Solar-Powered Plasmon-Enhanced Heterogeneous Catalysis

“…In both cases, the plasmonic material can selectively deposit the energy of photons into specific adsorbate electronic states thus activating the desired chemical bonds [116,117]. The mechanism is also known as desorption induced by electronic transition and consists of three fundamental steps: (i) charge carriers injection into the targeted molecular orbitals; (ii) coupling between the excited electronic state of the metallic NP and the excited vibrational state of the adsorbate; (iii) formation of the transient negative ion and promotion to a more energetic potential energy surface ( Figure 6B) [118][119][120][121][122][123]. By forcing the adsorbate-metal system to move to a different PES, the energy of hot carriers is converted into kinetic energy of the complex and specific chemical bonds can be activated.…”

Strong Influence of Coadsorbate Interaction on CO Desorption Dynamics on Ru(0001) Probed by Ultrafast X-Ray Spectroscopy andAb InitioSimulations

“…S1, S2 and S5 for modeled surface structures) [16]. Optical laser pulses initiate surface reactions, which for CO=Ruð0001Þ lead to desorption [9,10,[26][27][28] and for 2O-CO=Ruð0001Þ include both CO desorption and a minor contribution from oxidation to CO 2 [29][30][31]. The temperature profile of the electron and phonon subsystems induced by ultrafast optical lasers can be described using the two-temperature model [16,32,33].…”