Laser Spectroscopy and Photochemistry on Metal Surfaces

Dai, H-L; Ho, W.J.

doi:10.1142/2340-part2

Cited by 28 publications

(34 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…SHG is highly sensitive to a static electric field because it acts to break inversion symmetry over the accumulation region [ Fig.2]. Electric-field induced SHG is commonly observed in the context of metal-electrolyte interfaces [33] and is theoretically described by a thirdorder process P i (2ω) = χ [31,33,34]. Because χ (3) has the same symmetry constraints as χ (2) , the overall symmetry of the SHG intensity as a function of the crystal orientation must remain unchanged in the presence of E with each χ (2) tensor element simply being enhanced by the addition of a χ (3) E tensor element.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Theoretical and experimental study of second harmonic generation from the surface of the topological insulator Bi2Se3

et al. 2012

View full text Add to dashboard Cite

Section: Theoretical Backgroundmentioning

confidence: 99%

Theoretical and experimental study of second harmonic generation from the surface of the topological insulator Bi2Se3

et al. 2012

View full text Add to dashboard Cite

“…10 On the basis of previous studies, 11 the cage system seems to have a great influence on the outcome of photochemistry of trapped adsorbates on metal surfaces. 9,10,12 A unique property of the cage is associated with blocking any photodesorption pathway, 13,14 raising the probability of photoreaction followed by rearrangement and formation of new molecular species. 10,12 Another property of irradiated molecular cages is that the caged parent molecules and all irradiation products desorb simultaneously at the ASW crystallization with desorption onset near 165 K. This fact significantly facilitates the search for new photoproducts.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Ethyl Chloride with Amorphous Solid Water Thin Film on Ru(001) and O/Ru(001) Surfaces

Ayoub

Asscher

2009

J. Phys. Chem. A

View full text Add to dashboard Cite

The adsorption of ethyl chloride (EC) on clean and oxygen covered Ru(001) surfaces and its interaction with coadsorbed amorphous solid water (ASW) is reported based on temperature-programmed desorption (TPD) and work function change (4Φ) measurements. Adsorption of EC is characterized by a decrease of 2.1 eV in work function at monolayer coverage. Flipped adsorption geometry on average (ethyl facing the surface) is found in the second layer with a 0.3 eV increase in the work function. On ruthenium substrates the orientation of EC molecules could be controlled chlorine down or up by varying the oxygen coverage, as indicated by work function change measurements. ∆P-TPD from clean Ru(001) surface reveals a complete dissociation of the EC molecules on the clean Ru(001) surface at coverages up to 0.1 ( 0.05 ML. At higher coverage it leads to two distinct TPD peaks: at T )175 and 120-130 K, for the monolayer and multilayer coverage, respectively. Compression of preadsorbed 0.3 ML EC molecules into small islands on the surface occurs when ASW layers at coverage in the range 0.5-6 bilayers (BL) are adsorbed on top of the EC covered surface, associated with a shift in peak desorption from 190 K down to 125 K. A Caging process of EC molecules within the layers of ASW takes place by adsorbing more than 6 BL until a fully caged system has developed above 20 ASW BL. A reversed TPD peak shift of the trapped EC molecules occurs from its compressed phase at 125 K up to 165 K, the onset for ASW transition to crystalline ice and desorption. The detachment process leads to partial flipping over the geometry of the EC at the second layer, as determined by 4Φ measurement. The distance of the lifted and caged EC molecules from the Ru surface has been determined to reside 1.0 ( 0.2 nm above the solid surface, based on the thermal dissociation and hydrogen uptake measurements of sandwiched EC molecules between a variable thickness ASW film and a fixed 10 BL layer, on top of clean Ru(001). We conclude that the caged EC molecules are trapped in a micelle-like geometry with the ethyl groups pointing inward. This conclusion is based on photodecomposition studies of the caged EC molecules at 193 nm, as a function of EC initial coverage.

show abstract

“…S2). Fifth, changing the linear polarization of the laser, performed because signals in laser surface spectroscopy are often polarization-sensitive (22), leads to a strong signal variation over two orders of magnitude, evidencing a directional dependence of the interaction of the light and the adsorbate that is predetermined by the surface (Fig. S3).…”

Section: Resultsmentioning

confidence: 99%

“…Other types of lasers have been used earlier for this purpose, but starting from the first demonstration of intact desorption of NO molecules from a Pd(111) single crystal induced by femtosecond laser pulses (21), a complete field of ultrafast laser spectroscopy on metal surfaces has emerged among the diversity of surface chemistry techniques (22,23). Already in early time-resolved experiments (24-26) the unique reaction pathways accessible by the short pulses and the corresponding nonequilibrium excitation of the substrate's electronic system became apparent and revealed that femtosecond laser desorption is not only because of a phonon-assisted heating effect.…”

mentioning

confidence: 99%

Femtosecond quantum control of molecular bond formation

Nuernberger

Wolpert

Weiß

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Ultrafast lasers are versatile tools used in many scientific areas, from welding to eye surgery. They are also used to coherently manipulate light-matter interactions such as chemical reactions, but so far control experiments have concentrated on cleavage or rearrangement of existing molecular bonds. Here we demonstrate the synthesis of several molecular species starting from small reactant molecules in laser-induced catalytic surface reactions, and even the increase of the relative reaction efficiency by feedbackoptimized laser pulses. We show that the control mechanism is nontrivial and sensitive to the relative proportion of the reactants.The control experiments open up a pathway towards photocatalysis and are relevant for research in physics, chemistry, and biology where light-induced bond formation is important.femtochemistry | surface science E ver since their invention, lasers were considered the ideal tool for microscopic control over chemical bonds, and several seminal coherent control approaches have been developed (1-3). A very successful method to this task is femtosecond quantum control, where selectivity over photoinduced reactions is achieved by exploiting the coherence properties and ultrashort time scales of femtosecond laser radiation (4-6). Combined with learning algorithms processing experimental feedback to adaptively find optimized pulses best suited for solving the control task (7), chemical reactions can even be controlled without a priori knowledge about the reaction mechanisms. This scheme has been successfully applied to dissociative reactions in the gas phase, first on organometallic compounds (8) and later on many other systems. The method is not limited to gas phase experiments, as fluorescence optimizations of molecules in the liquid phase have shown (9-12). Recently, also more complex control tasks have been realized, like the energy flow in large biomolecules (13) or the quantum yield in a photoisomerization reaction (14-16). Femtosecond lasers have also been introduced to the field of photoassociation from atoms in cold traps, in both theory (17,18) and first experiments (19,20). However, the selective laser manipulation of bond-forming reactions starting from small reactant molecules that may furthermore exhibit competing bond-forming reaction channels has not been shown yet.In this contribution, we present the realization of femtosecond laser-assisted catalytic reactions of carbon monoxide and hydrogen or deuterium at a metal surface and further demonstrate that the relative reaction efficiency can be increased by the benefits of femtosecond laser pulses tailored especially for a desired reaction outcome. These experiments represent a first step and a reaction path toward laser-induced catalysis of molecular systems.Femtosecond laser sources have been employed by laser scientists to explore processes on metal surfaces as soon as they were available. Other types of lasers have been used earlier for this purpose, but starting from the first demonstration of intact desorption of ...

show abstract

Laser Spectroscopy and Photochemistry on Metal Surfaces

Cited by 28 publications

References 0 publications

Theoretical and experimental study of second harmonic generation from the surface of the topological insulator Bi2Se3

Theoretical and experimental study of second harmonic generation from the surface of the topological insulator Bi2Se3

Interaction of Ethyl Chloride with Amorphous Solid Water Thin Film on Ru(001) and O/Ru(001) Surfaces

Femtosecond quantum control of molecular bond formation

Contact Info

Product

Resources

About