Pulsed laser induced thermal desorption of CO from copper surfaces

Burgess, Donald R.; Viswanathan, R.; Hussla, Ingo; Stair, Peter C.; Weitz, Eric

doi:10.1063/1.445647

Cited by 91 publications

(15 citation statements)

References 11 publications

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“…45 However, the few prior LITD experiments of CO from metal surface in the literature could not be interpreted in terms of a simple equilibrium picture of the LITD process. 46,47 We do not know why these earlier experiments did not observe the simple equilibrium LITD behavior. One experimental difference is that in our experiments only a small fraction of adsorbed CO ͑ca.…”

Section: E T S Measurements: Litd Of Comentioning

confidence: 80%

Laser assisted associative desorption of N2 and CO from Ru(0001)

Diekhöner¹,

Mortensen²,

Baurichter³

et al. 2001

The Journal of Chemical Physics

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An experimental technique, laser assisted associative desorption ͑LAAD͒, is described for determining adiabatic barriers to activated dissociation at the gas-surface interface, as well as some aspects of the dynamics of associative desorption. The basis of this technique is to use a laser induced temperature jump ͑T-jump͒ at the surface to induce associative desorption and to measure the translational energy distribution of the desorbing molecules. The highest translational energies observed in desorption are a lower bound to the adiabatic barrier and the shapes of the translational energy distributions provide information on the dynamics. Implementation of the experimental technique is described in detail and unique advantages and possible limitations of the technique are discussed. The application of this technique to very high barrier surface processes is described; associative desorption of N 2 from Ru͑0001͒ and CO formed by CϩO and C 2 ϩO on Ru͑0001͒. N 2 barriers to dissociation increases strongly with N coverage and co-adsorbed O, in good agreement with DFT calculations. No isotope effects are seen in the associative desorption, indicating that tunneling is not important. The full energy distributions suggest that very large energy loss to the lattice occurs after recombination at the high barrier and prior to N 2 desorption into the gas phase. The mechanism for this remarkably large energy loss is not well understood, but is likely to be general for other high barrier associative desorption reactions. CO associatively desorbs nearly thermally from both CϩO and C 2 ϩO associative reactions. It is argued that this is due to large energy loss for this system as well, followed by indirect scattering in the deep CO molecular well before final exit into the gas phase.

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Section: E T S Measurements: Litd Of Comentioning

confidence: 80%

Laser assisted associative desorption of N2 and CO from Ru(0001)

Diekhöner¹,

Mortensen²,

Baurichter³

et al. 2001

The Journal of Chemical Physics

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“…If a8< 1, TJ;::;:,a8, (17) i.e., TJ is proportional to the absorption coefficient a. On the other hand, if a8> 1, TJ;::;:, 1,…”

Section: Hot Carrier Interactionmentioning

confidence: 99%

Photodissociation of adsorbed Mo(CO)6 induced by direct photoexcitation and hot electron attachment. II. Physical mechanisms

Ying¹,

Ho²

1991

The Journal of Chemical Physics

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Articles you may be interested inPlasmon-induced photoexcitation of "hot" electrons and "hot" holes in amorphous silicon photosensitive devices containing silver nanoparticles The wavelength dependence of photoinduced hot electron dissociative attachment to methyl bromide adsorbed on gallium arsenide (110) Photodissociation of adsorbed Mo(CO)6 induced by direct photoexcitation and hot electron attachment. I. Surface chemistryPhotodissociation of Mo (CO) 6 adsorbed on potassium-free and potassium-preadsorbed Cu( 111) and SiC 111)7 X 7 at 85 K has been studied under ultrahigh vacuum conditions. The photodissociation yield has been measured as a function of photon power (0.5-30 m W I cm 2 ), wavelength (250-800 nm), polarization (s andp), and incident angle (20°_70°). Two surface photoreaction mechanisms are considered: (i) direct electronic excitation of the adsorbate and (ii) attachment of photogene rated hot carriers to the adsorbate. The photodissociation spectra obtained on K-free Cu( 111) and SiC 111)7 X 7 exhibit the same resonant structure as the absorption spectrum ofMo(CO)6' Photodissociation ofMo(CO)6 on K-free surfaces is thus determined to be dominated by direct electronic excitation of the adsorbate, which proceeds via a single-photon process. A new photodissociation channel is opened on K-preadsorbed surfaces. The photoyield increases substantially in the UV and extends to the visible and near IR. By studying the wavelength and polarization dependences of the photoyield, it is firmly established that the new photodissociation channel is due to interaction of photogenerated hot carriers with the adsorbate. The photogenerated hot electrons tunnel through the potential barrier between the adsorbed MO(CO)6 and substrate and attach to the MO(CO)6 molecules. This mechanism is energetically possible in the presence of K due to a substantial up-shift in the Fermi level associated with the decrease in the work function. The negative ions formed by electron attachment are unstable and undergo dissociation.

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“…Using equation (5) for the number of the evaporated monolayers Θ, one can obtain the final formula for the TOF distribution (16) as functions of the number of internal degrees of freedom j (points). The solid line corresponds to equation (17) and the dashed line to equation (23).…”

Section: Final Formulamentioning

confidence: 99%

“…Expression (2) was initially used to analyze velocity distributions under supersonic expansion in molecular beams [13,14]. Later it was applied for the analysis of molecular scattering from a surface [15] and pulsed desorption and sputtering [16][17][18][19]. For steady jets the fitting parameters V flow and T flow correspond to the jet velocity and temperature at the skimmer entrance.…”

Section: Introductionmentioning

confidence: 99%

Analytical formula for interpretation of time-of-flight distributions for neutral particles under pulsed laser evaporation in vacuum

Morozov¹

2015

J. Phys. D: Appl. Phys.

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A theoretical study of the time-of-flight (TOF) distributions of neutral species produced by low-fluence pulsed laser evaporation in a vacuum has been performed. A database of TOF distributions has been calculated by the direct simulation Monte Carlo method. The calculated TOF signals have been fitted by a modification of the shifted Maxwell-Boltzmann distribution function with the only parameter being the shift velocity. The dependence of the shift velocity on the number of evaporated monolayers has been described by an analytical expression, derived based on the gas-dynamic analysis of pulsed gas expansion into a vacuum. This expression allows the derivation of a new formula for TOF distributions for neutral particles with the only parameter being the surface temperature. This new formula has been used for the analysis of experimental data on pulsed laser ablation of niobium, copper, graphite and gold. The evaluated surface temperature agrees well with the results of the thermal model calculations and available experimental data with an error of 10% instead of 50-150% for commonly used formulas.

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Pulsed laser induced thermal desorption of CO from copper surfaces

Abstract: Selective excitation of coupled CO vibrations on a dissipative Cu(100) surface by shaped infrared laser pulses

Cited by 91 publications

References 11 publications

Laser assisted associative desorption of N2 and CO from Ru(0001)

Laser assisted associative desorption of N2 and CO from Ru(0001)

Photodissociation of adsorbed Mo(CO)6 induced by direct photoexcitation and hot electron attachment. II. Physical mechanisms

Analytical formula for interpretation of time-of-flight distributions for neutral particles under pulsed laser evaporation in vacuum

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