<i>2π</i>affinity level of adsorbed CO: Bonding and dispersion

Rogozik, J.; Dose, V.; Prince, Kevin C.; Bradshaw, A. M.; Bagus, Paul S.; Hermann, Klaus; Avouris, Phaedon

doi:10.1103/physrevb.32.4296

Cited by 76 publications

(11 citation statements)

References 24 publications

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“…By inverse photoemission it is found to be located 4.9 eV above the Fermi energy (E F ) for the saturation coverage of CO/Ru͑001͒, 53 in contrast to CO/Cu͑100͒, 54 where a doublet resonance is found at 2.4 and 3.9 eV above E F . Given the experimental conditions, the electronic temperatures reach values of T el max Ϸ3400 K and 6900 K for CO/Cu and CO/Ru, respectively.…”

Section: Discussionmentioning

confidence: 90%

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

Funk

Bonn

Denzler

et al. 2000

The Journal of Chemical Physics

104

174

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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.

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Section: Discussionmentioning

confidence: 90%

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

Funk

Bonn

Denzler

et al. 2000

The Journal of Chemical Physics

104

174

View full text Add to dashboard Cite

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“…p 2 ͒R45 ± compression phase at the saturation coverage of 0.57 ML [10]. For the clean and CO-covered Cu(100) surface the vacuum level is located close to the center of the band gap of the projected bulk band structure and a series of image-potential states can be observed [3,4].…”

mentioning

confidence: 99%

Control of the Dephasing of Image-Potential States by CO Adsorption on Cu(100)

et al. 1999

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“…The electronic levels of the system have been characterized using inverse photoemission, indicating two unoccupied levels centered at 2.6 and 3.6 eV above the Fermi level, related to the CO 5<r and 2/r* levels [7,8]. Infrared reflection-absorption spectroscopy (IRAS) [9,10] and helium atom scattering [11] have identified the four fundamental vibrational modes: the CO stretch at vi =2086 cm" 1 , the Cu-CO stretch at v 2 =345 cm" 1 , the frustrated rotation at v>3=285 cm" 1 , and the frustrated translation at V4 = 32 cm" 1 .…”

mentioning

confidence: 99%

Hot carrier excitation of adlayers: Time-resolved measurement of adsorbate-lattice coupling

et al. 1993

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Picosecond time-resolved infrared absorption measurements of CO/Cu(100) following visible and ultraviolet laser pumping allow a determination of the time scales for photoexcited carriers and lattice phonons to couple to the CO frustrated translation vibrational mode.PACS numbers: 68.35.Ja, 42.62.Fi, 63.20.Kr, 78.47.+p Since low frequency vibrational modes of adsorbates are the precursors to motion about and away from a surface, energy transfer through these modes plays important roles in a wide range of interface processes. For example, calculations of surface diffusion rely upon knowledge of the frictional damping rates of frustrated translations [1], Reactions between molecules on neighboring sites rely on activation of these modes to bring the molecules together. Recently, the field of femtosecond surface photochemistry has opened up a realm of novel interactions of molecules with nonequilibrium substrate degrees of freedom. Ultimately, an understanding of these processes requires knowledge of the various pathways by which the low frequency modes can couple to the substrate degrees of freedom [2][3][4][5]. However, the low cross sections for optical absorption and the lack of available time-resolved spectroscopies at these frequencies have prevented the direct measurement of the lifetimes of these modes.By observing the vibrational response of an adsorbate during ultrashort laser heating of a substrate, the time scales and mechanisms for surface-molecule energy transfer can be revealed. In this Letter, time-resolved measurements of the transient response of CO/Cu(100) to picosecond laser excitation are presented. Unlike previous measurements of substrate-adsorbate coupling strengths [6], these results unambiguously establish the contribution of transiently heated substrate electrons and phonons in activating the low frequency adsorbate vibrational modes and allow the coupling times of the frustrated translational mode to hot carriers and phonons to each be determined.The 0.5 monolayer (ML) (1 ML=7.67xl0 14 cm" 2 ) (V5xV2)/?45° overlayer of CO on Cu(100) at 100 K has been well characterized in terms of both adsorbate vibrational modes and low lying unoccupied electronic states. The electronic levels of the system have been characterized using inverse photoemission, indicating two unoccupied levels centered at 2.6 and 3.6 eV above the Fermi level, related to the CO 53=285 cm" 1 , and the frustrated translation at V4 = 32 cm" 1 . We have made independent steady state IRAS measurements [12] on the same crystal used for the time-resolved experiments, determining the temperature dependence of the CO stretch mode vi =2086-0.031 [T(K) -100] cm" 1 and width 8v x =3.9 + 0.005[r(K)-100] cm" 1 . This behavior is readily accounted for by dephasing of ...

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2πaffinity level of adsorbed CO: Bonding and dispersion

Cited by 76 publications

References 24 publications

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

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

Control of the Dephasing of Image-Potential States by CO Adsorption on Cu(100)

Hot carrier excitation of adlayers: Time-resolved measurement of adsorbate-lattice coupling

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