Dynamics of the C–O stretch vibration on Si(100)

Laß, Kristian; Han, Xu; Hasselbrink, Eckart

doi:10.1016/j.susc.2005.12.081

Cited by 15 publications

(15 citation statements)

References 23 publications

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“…13 In parallel work we have recently studied the vibrational dynamics of a molecular adsorbate, namely, CO on Si͑100͒. [14][15][16] Apart from these fundamental aspects as benchmark systems, hydrogenated silicon has been widely studied due to its role for many processes in material processing. Germanium has recently gained in importance for semiconductor industries.…”

Section: Introductionmentioning

confidence: 99%

Vibrational dynamics of hydrogen on Ge surfaces

Han

Balgar

Hasselbrink

2009

The Journal of Chemical Physics

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The vibrational dynamics of the H stretch excitation on the Ge(100)-(2x1) and Ge(111)-(1x1) surfaces has been studied using picosecond IR pump-SFG probe spectroscopy. Moreover, the temperature dependence and an isotope mixture effect are reported. The symmetric stretching mode at 1994 cm(-1) on the Ge(100)-(2x1):H surface shows a single-exponential relaxation with a decay constant of 4.8+/-0.6 ns at 100 K with a strong temperature dependence, while the Ge-H stretch at 1975 cm(-1) on the Ge(111)-(1x1):H surface relaxes four times faster with a 1.3+/-0.2 ns lifetime also exhibiting a weaker temperature dependence. The lifetime decreases with increasing temperature to 1.6 and 0.74 ns at 400 K on Ge(100) and Ge(111), respectively. We find that the decay rate increases by a factor of 3-6 depending on sample temperature when the Ge(100) surface dimers are saturated with an isotope mixture of H and D. Such an effect upon isotope mixing is not observed for the Ge(111) surface. The results suggest for the Ge(100)-(2x1):H system that a decay into three bending mode quanta requires the creation of two-optical phonons to satisfy energy conservation, whereas the decay into four bending quanta requires the annihilation of only one phonon. The three bending quanta process is hence the slower one. However, the decay into four bending quanta shows a strong temperature dependence. For an isotope mixture covered surface a larger number of combinations of low-frequency adsorbate modes exist facilitating a faster decay of the stretching excitation.

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Section: Introductionmentioning

confidence: 99%

Vibrational dynamics of hydrogen on Ge surfaces

Han

Balgar

Hasselbrink

2009

The Journal of Chemical Physics

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“…Accumulation of vibrational energy at molecules on surfaces is competitive against dissipation into equilibrium. For instance, the lifetime of the C-O stretching vibration on Pt(111) is 2.2 ps [14], whereas that of CO on Si(001) is 1.87 ns [15,16]. The latter longer lifetime suggests that the accumulated energy would overcome the reaction barrer, but the observed rate in vibration-induced reaction follows a linear relation on a semiconductor [17].…”

Section: Introductionmentioning

confidence: 99%

Molecular Motion on Semiconductor Surface via Tip-enhanced Multiple Excitation

Momose,

Shudo,

Raebiger

et al. 2012

Preprint

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In a low-temperature study with a scanning tunneling microscope (STM), the irreducible lateral motion of a CO molecule adsorbed on a Si(001) surface showed a hyperlinear dependence on the tunneling current. This dependence implies that the adsorbate displacement is caused by multiple excitations of adsorbate vibration modes, a situation thus far observed only at metal surfaces. The local vibronic temperature at the atomic scale on the surface heated by ohmic inelastic scattering of tunneling electrons indicates that there is an activation barrier of 0.11 eV for the irreversible motion of CO, in agreement with the adiabatic potential obtained from first-principles calculation. The highly efficient local heating is caused by a mid-gap state at the surface induced by the electric field of the STM tip.

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“…The lifetime of vibrationally excited molecules strongly depends on the substrate. Relaxation of CO in the first vibrationally excited state shows picosecond lifetimes on metal surfaces, [9,10] nanosecond lifetimes on semiconductor surfaces (Si(100)), [12,13] and millisecond lifetimes on insulator surfaces (NaCl (100)). [16] The fundamental difference in the lifetimes is attributed to different vibrational relaxation mechanisms that occur on the various types of substrates.…”

Section: Vibrational Relaxationmentioning

confidence: 99%

“…Those spherical multipole moments agree with the "𝑧 𝑙 "-components of the cartesian multipole moments. 13 The correspondence between the cartesian and spherical multipole moments is as follows: 𝑄 00 = 𝑞 (charge),…”

Section: Electrostatic Interactions Between Two Moleculesmentioning

confidence: 99%

“…On the silicon surface, vibrational excitation decays within nanoseconds. [12][13][14][15] In contrast, the much smaller vibrational relaxation efficiency on insulators [16,17] makes it much easier to study highly vibrationally excited molecules directly at the surface, for example with surface infrared spectroscopy. [18,19] Figure 1.1: (a) Schematic representation of the CO/NaCl( 100) monolayer structure at 7 K. Black, red, green and purple spheres represent carbon, oxygen, chlorine and sodium atoms, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational Energy Transfer Between CO Molecules on a NaCl(100) Surface Studied by Infrared Fluorescence Spectroscopy

Alexander¹

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The breaking of chemical bonds in surface reactions is inherently connected to highly excited molecular vibrations. Therefore, understanding the vibrational energy transfer dynamics of adsorbed molecules, which effectively determine the lifetime of vibrational excitation, is of great importance. CO adsorbed on NaCl(100) is possibly the best studied physisorbed molecule. Despite that, most previous experiments have focused on the vibrational ground state and the 𝑣 = 0 → 1 transition of CO-mainly because dispersed fluorescence from high vibrational states could not be observed with conventional infrared detectors. In this thesis, I thus investigate the vibrational energy transfer dynamics of CO on NaCl(100) in highly vibrationally excited states up to 𝑣 = 30.Dispersed and time-resolved laser-induced fluorescence (LIF) is used to observe the vibrational dynamics. For this, an improved version of a recently developed mid-infrared emission spectrometer based on superconducting nanowire single-photon detectors (SNSPDs) is used. The current setup is capable of detecting infrared fluorescence from a single adsorbate layer with spectral and temporal resolution of 7 nm and ∼1 µs, respectively. High vibrational states, CO(𝑣), are prepared by pulsed infrared laser excitation of CO to 𝑣 = 1 at cryogenic temperatures around 7 K. Subsequent vibrational energy pooling (VEP), driven by the anharmonicity of the CO oscillators, concentrates many vibrational quanta in single molecules via vibration-to-vibration (V-V) energy transfer from the surrounding molecules: CO(n) + CO(m) → CO(n+1) + CO(m -1).Kinetic Monte Carlo simulations of the vibrational dynamics in a 13 C 18 O monolayer show that VEP proceeds via a sequential mechanism, in which adsorbates in high vibrational states are further excited by collecting vibrational quanta from molecules in lower vibrational states over increasingly large distances and timescales, up to 100 µs. The shape of the phonon spectrum, to which the excess energy in the V-V transfer processes is dissipated, causes a distinct peak structure in the vibrational state distribution. Furthermore, dissipation to transverse phonons that involve Na atom motion in the surface plane is found to be most effective. Vibrational relaxation to the NaCl substrate is slower than VEP and occurs on the millisecond time scale for 𝑣 ≤ 23. The 𝑣-dependent relaxation rates can be explained by a classical electrodynamic mechanism, whereby energy is transferred non-radiatively to the absorbing NaCl medium via the near-field of the oscillating CO dipole. This finding is in strong contrast to the dominating mechanism for more strongly bound adsorbates, where energy is dissipated via anharmonic couplings between the CO vibration and the surface phonons.The improved resolution of the emission spectrometer revealed a previously unknown metastable O-down orientation (Na + -OC), which is formed from the stable C-down v First and foremost, I would like to express my deepest gratitude to my supervisor Alec Wodtke for getting the chance...

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Dynamics of the C–O stretch vibration on Si(100)

Cited by 15 publications

References 23 publications

Vibrational dynamics of hydrogen on Ge surfaces

Vibrational dynamics of hydrogen on Ge surfaces

Molecular Motion on Semiconductor Surface via Tip-enhanced Multiple Excitation

Vibrational Energy Transfer Between CO Molecules on a NaCl(100) Surface Studied by Infrared Fluorescence Spectroscopy

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