Vibrational energy transfer of CO/Cu(100): Nonadiabatic vibration/electron coupling

Morin, Mario; Levinos, N. J.; Harris, A. L.

doi:10.1063/1.461897

Cited by 244 publications

(203 citation statements)

References 41 publications

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“…Depopulation of vibrational eigenstates of adsorbates on metal substrates via formation of electron-hole pairs is expected to proceed on the picosecond time scale [7,8], or even faster [9,10]. This is about the time scale that can be reached with the 3 He spin-echo technique.…”

Section: Primary Results From These Experiments Is the Intermediate Scmentioning

confidence: 99%

Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

Firmino

Marquardt

Gatti

et al. 2014

J. Phys. Chem. Lett.

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Diffusion rates are calculated on the basis of van Hove's formula for the dynamical structure factor (DSF) related to particle scattering at mobile adsorbates. The formula is evaluated quantum mechanically using eigenfunctions obtained from three dimensional realistic models for H/Pd(111) derived from first principle calculations. Results are compatible with experimental data for H/Ru(0001) and H/Pt(111), if one assumes that the total rate obtained from the DSF is the sum of a diffusion and a friction rate. A simple kinetic model to support this assumption is presented.

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Section: Primary Results From These Experiments Is the Intermediate Scmentioning

confidence: 99%

Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

Firmino

Marquardt

Gatti

et al. 2014

J. Phys. Chem. Lett.

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“…Using picosecond (ps) techniques, information about the dynamics of energy exchange between adsorbed carbon monoxide (CO) and metal substrates has been obtained [4], by monitoring transient band shifts of the C-O vibration after optical excitation. The technique has further been used to observe vibrational energy relaxation [5] and reversible transient chemical transformations [6] at surfaces. These experiments were limited to temperatures below those at which desorption of the adsorbate occurs.…”

Section: Femtosecond Surface Vibrational Spectroscopy Of Co Adsorbed mentioning

confidence: 99%

Femtosecond Surface Vibrational Spectroscopy of CO Adsorbed on Ru(001) during Desorption

et al. 2000

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Using time-resolved sum-frequency generation spectroscopy, the C-O stretch vibration of carbon monoxide adsorbed on a single-crystal Ru(001) surface is investigated during femtosecond near-IR laser excitation leading to desorption. A large transient redshift, a broadening of the resonance, and a strong decrease in intensity are observed. These originate from coupling of the C-O stretch to low-frequency modes, especially the frustrated rotation, that are highly excited in the desorption process. PACS numbers: 68.35.Ja, 33.70.Jg, 78.47. + p, 82.20.Rp The dynamics of the interaction between molecules and metal surfaces is of fundamental importance in surface science, since these determine key physical and chemical properties-essential in, e.g., catalysis-such as energy transfer and molecular reactivity [1] [6] at surfaces. These experiments were limited to temperatures below those at which desorption of the adsorbate occurs. However, when one is interested in surface reactions, the more relevant situation occurs at higher temperatures, where higher-lying vibrational modes get thermally occupied that play an important role in the surface chemistry.We present here femtosecond time-resolved vibrational sum-frequency generation (fs-SFG) spectra of CO molecules adsorbed on a Ru(001) surface, taken while a significant number (ϳ50%) of these molecules is desorbing due to fs laser excitation. With this fs-SFG method, snapshots of the (C-O) stretch vibration can be taken, under conditions where desorption is occurring (at lattice temperatures transiently exceeding the desorption temperature by over 500 K), shedding new light on the dynamics of the desorption process and the coupling of vibrational modes at the surface.The experiments were carried out in an ultrahigh vacuum chamber (base pressure 1 3 10 210 mbar) equipped with standard surface science tools. Our commercial laser system produces 800 nm, 110 fs pulses of 4.5 mJ͞pulse at 400 Hz, chopped down to 20 Hz for these experiments. One-third of the energy is used to excite the surface ("pump" pulse, typical absorbed fluence 55 J͞m 2 [7]), and the remaining energy is used to pump an optical parametric generator/amplifier (OPG͞OPA) providing tunable (l 2 10 mm, bandwidth ϳ150 cm 21 ) IR pulses with an energy of typically 10 mJ and a duration of 150 fs. The portion of the 800 nm pulse which is not converted into IR in the OPG͞OPA-process is spectrally narrowed down to 4 cm 21 , and is used in the SFG experiments as the visible (VIS) up-conversion pulse. An extensive description of the complete experimental setup as well as the surface cleaning, preparation, and characterization procedures can be found in Ref. [8].The surface sensitivity of SFG relies on the fact that the second-order nonlinear susceptibility is nonvanishing at interfaces [9]. This enables the generation of an electric field E SFG out of two incidents fields E VIS and E IR , where energyhv and parallel momentum k k must be con-For frequencies v IR within the IR bandwidth resonant with the vibrational tra...

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“…7 Specifically, adiabatic theories predict millisecond lifetimes whereas electronic friction calculations result in picosecond lifetimes, in good agreement with experiment. 8 The successes of friction theory suggest that major adjustments to the adiabatic picture might not be necessary.Recently, multi-quantum vibrational relaxation, 9 vibrationally promoted electron emission 10,11 and electron mediated vibrational overtone excitation 12 in molecule-surface scattering have been reported by our group. It is unclear if these phenomena can be described by electronic friction theories.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Vibrationally promoted electron emission at a metal surface: electron kinetic energy distributions

LaRue

Schäfer

Matsiev

et al. 2011

Phys. Chem. Chem. Phys.

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We report the first direct measurement of the kinetic energy of exoelectrons produced by collisions of vibrationally excited molecules with a low work function metal surface exhibiting electron excitations of 64% (most probable) and 95% (maximum) of the initial vibrational energy. This remarkable efficiency for vibrational-to-electronic energy transfer is in good agreement with previous results suggesting the coupling of multiple vibrational quanta to a single electron.Understanding the interactions of molecules with solid surfaces is important to the development of predictive theories of surface chemistry, 1,2 which up to now routinely assume electronic adiabaticity. According to this assumption, one may calculate an effective potential energy surface upon which the atoms move based on the Born-Oppenheimer approximation, where the system remains in its electronic ground state. While this approach enables highly detailed calculations to be carried out, it neglects possible energy transfer channels between nuclear motion and electronic degrees of freedom in the metal.Reports of laboratory observations of electronically nonadiabatic influences on molecule-surface interactions are now becoming increasingly available, 3-5 yet it remains an open question whether such effects are important enough to require major adjustments to the electronically adiabatic picture. 6 For example, including nonadiabatic influences such as electronic friction, employing a weak coupling approximation, has been remarkably successful in addressing the inadequacies of the adiabatic assumption in describing vibrational lifetimes of small molecules on metal surfaces. 7 Specifically, adiabatic theories predict millisecond lifetimes whereas electronic friction calculations result in picosecond lifetimes, in good agreement with experiment. 8 The successes of friction theory suggest that major adjustments to the adiabatic picture might not be necessary.Recently, multi-quantum vibrational relaxation, 9 vibrationally promoted electron emission 10,11 and electron mediated vibrational overtone excitation 12 in molecule-surface scattering have been reported by our group. It is unclear if these phenomena can be described by electronic friction theories. For example, multi-quantum vibrational relaxation of NO(v = 14,15) on Au(111) is at least semi-quantitatively reproduced by friction-like theories. 13 However, good agreement with experiment is also found using a multi-state (independent electron surface hopping) model, 14-16 where a single electron transfer mechanism is operative.Putting it another way, a fundamental unknown is the fraction of molecular vibration that can be converted to single electron excitation and vice versa. For example, one might envision that a single highly excited electron in a solid could transfer nearly all of its excitation energy to a molecule at the surface. If that were possible, time reversal suggests that a highly excited molecule would be able to transfer all (or nearly all) of its excitation energy to a single electr...

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Vibrational energy transfer of CO/Cu(100): Nonadiabatic vibration/electron coupling

Cited by 244 publications

References 41 publications

Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

Femtosecond Surface Vibrational Spectroscopy of CO Adsorbed on Ru(001) during Desorption

Vibrationally promoted electron emission at a metal surface: electron kinetic energy distributions

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