CH Vibration Softening and the Dehydrogenation of Hydrocarbon Molecules on Ni(111) and Pt(111)

Demuth, J. E.; Ibach, H.; Lehwald, S.

doi:10.1103/physrevlett.40.1044

Cited by 259 publications

(127 citation statements)

References 10 publications

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“…In addition, the physisorption of alkanes has been studied on Au(111), 6 Pt(111), 7,8 Pt(110), 9 Ir(110), 10 Cu(100), 11 Ru(001), 12 and Cu(111), 13 under UHV conditions. However, the local arrangement of the alkanes on a metal surface has not been investigated in contrast to numerous reports of alkane adlayers on graphite at the solid/liquid interface, [14][15][16][17][18][19][20][21] although studies using molecular dynamics 12,[22][23][24][25][26][27] and infrared spectroscopy [28][29][30][31][32] under UHV conditions have been carried out after the reports by Firment and Somorjai. Furthermore, the structure of the alkane/metal interface in solution was not investigated.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Crystals of Alkanes Formed on Au(111) Surface in Neat Liquid: Structural Investigation by Scanning Tunneling Microscopy

Yamada

Uosaki

2000

J. Phys. Chem. B

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In situ scanning tunneling microscopy revealed the formation of the two-dimensional (2D) crystals of n-alkanes (C n H 2n+2 , n ) 12-17) on a Au(111) surface in neat liquid at room temperature. The molecules were adsorbed on the gold surface with their molecular axis parallel to the surface plane. The molecular rows of even-and odd-numbered alkanes ran in the nearest-neighbor (NN) atomic direction and the next-nearest-neighbor atomic direction of the gold surface, respectively. The molecular axis was oriented close to the NN direction of the gold surface in both odd-and even-numbered alkanes. Although there are two NN directions with respect to the direction of the bridging row of the herringbone structure due to the reconstruction of the Au(111) surface with crossing angles of 30°and 90°, the molecular axis was preferentially oriented in the NN direction with a crossing angle of 30°. The 2D crystal of alkanes was not formed on the iodine-modified Au(111) surface, confirming that the molecule-substrate interaction played an important role in forming the 2D crystal of alkanes.

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Section: Introductionmentioning

confidence: 99%

Two-Dimensional Crystals of Alkanes Formed on Au(111) Surface in Neat Liquid: Structural Investigation by Scanning Tunneling Microscopy

Yamada

Uosaki

2000

J. Phys. Chem. B

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“…The adsorption energies of n-alkane molecules on metal substrates are rather small (of the order of 10 kJ/mol/CH 2 chain) [2], and the n-alkane-metal interaction has been categorized to be typical of physical adsorption. However, a softening of the C-H vibration has been observed for the n-alkane/metal system with vibrational spectroscopy [3,4]. The softening indicates that the simple physical adsorption picture is too simplified and there should be some interaction between n-alkanes and metals.…”

Section: : Introductionmentioning

confidence: 99%

“…The interaction between alkanes and metals has attracted wide attention [1][2][3][4][5]. This is due to the fact that many catalytic processes involve the conversion of saturated hydrocarbons to various products, and also because n-alkane is the simplest molecule among the saturated hydrocarbons.…”

Section: : Introductionmentioning

confidence: 99%

Electronic structure of octane on Cu(1 1 1) and Ni(1 1 1) studied by near edge X-ray absorption fine structure

et al. 2007

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The electronic structure of an octane film grown on Cu(111) and Ni(111) was studied using C K-edge near edge X-ray absorption fine structure (NEXAFS). A pre-peak was observed on the bulk edge onset for the 1 ML thick octane films on the metal substrates. The pre-peak originated from metal-induced gap states (MIGS) in the band gap of octane. The intensity of the pre-peak for octane/Ni(111) was the same as that of octane/Cu(111), suggesting that there was little difference in the density of unoccupied MIGS between the octane film on Ni (111) and Cu(111). We discuss the metal dependence of the density of unoccupied MIGS on the band structure of the metals.

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“…A CH stretching band has been shown to significantly broaden and redshift from the other symmetric and anti-symmetric CH stretching bands for cyclohexane on Ni(111) and Pt(111). 25 The origin of the CH vibrational mode softening has been extensively discussed in the past. Raval et al [26][27][28] have suggested that a hydrogen-bonding-like interaction exists between a metal surface and CH groups, which lie in close proximity to it.…”

Section: Photochemistry Of Saturated Hydrocarbonsmentioning

confidence: 99%

“…Moreover, there is another problem involving saturated hydrocarbon adsorption on metal surfaces, i.e., ''CH vibrational mode softening.'' [25][26][27][28][29][30][31][32][33][34] Saturated hydrocarbons adsorbed on metal surfaces show that one of CH stretching absorption bands is significantly redshifted. In this section, the electronic excitation mechanism of the photochemistry of small saturated hydrocarbons, i.e., methane and cyclohexane, is discussed together with a plausible origin for the CH vibrational mode softening.…”

Section: Photochemistry Of Saturated Hydrocarbonsmentioning

confidence: 99%

Photochemistry and Photo-Induced Ultrafast Dynamics at Metal Surfaces

Matsumoto¹

2007

Bulletin of the Chemical Society of Japan

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This account describes excitation mechanisms and ultrafast nuclear dynamics at metal surfaces induced upon photon irradiation. After reviewing possible excitation mechanisms for photochemistry of adsorbates on metal surfaces, we discuss the ultra-violet photochemistry of saturated hydrocarbons, i.e., methane and cyclohexane, on metal surfaces. Although these alkanes in the gas phase do not absorb photons at %6 eV, CH bond dissociation takes place upon 6.4-eV photon irradiation on metal surfaces. Hybridization between CH antibonding orbitals of the alkanes and metal bands, forming a new band across the Fermi level, is proposed to be responsible for both the photochemistry and CH vibrational mode softening. Since electronic relaxation at metal surfaces takes place very rapidly, most of excited adsorbates do not proceed to dissociation and/or desorption, but rather they are vibrationally excited. To probe photo-induced nuclear motions in real time, we developed femtosecond (fs) time-resolved second harmonic generation spectroscopy on metal surfaces. This method was used to explore the dynamics of photo-excited coherent vibration at Pt(111) surfaces covered with alkali-metal atoms. Irradiation of fs pump-laser pulses induced coherent vibrational motions of the stretching vibration of alkali atoms with respect to the metal surface and the Rayleigh modes of the Pt surface, which manifest themselves in modulations of second harmonic intensity of probe pulses. We also demonstrated that selective excitation of a phonon mode can be achieved by using tailored light pulse trains.

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CH Vibration Softening and the Dehydrogenation of Hydrocarbon Molecules on Ni(111) and Pt(111)

Cited by 259 publications

References 10 publications

Two-Dimensional Crystals of Alkanes Formed on Au(111) Surface in Neat Liquid: Structural Investigation by Scanning Tunneling Microscopy

Two-Dimensional Crystals of Alkanes Formed on Au(111) Surface in Neat Liquid: Structural Investigation by Scanning Tunneling Microscopy

Electronic structure of octane on Cu(1 1 1) and Ni(1 1 1) studied by near edge X-ray absorption fine structure

Photochemistry and Photo-Induced Ultrafast Dynamics at Metal Surfaces

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