Electrochemical tuning of the lifetime of the CO stretching vibration for CO/Pt(111)

Abstract

We have used the large electric fields at the interface of a Pt(111) electrode and an acetonitrile electrolyte solution to tune the interaction between adsorbed CO and the Pt(111) surface. The electrode potential is varied over a 2.5 Volt range. As the electrode potential is made more positive, the CO vibrational frequency increases and the vibrational lifetime decreases. Over the potential range investigated, the tuning is about 35–40 cm−1 and the lifetime varies from ≊2.1 to ≊1.5 ps. Ab initio calculations performed for CO/Cu(100) predicted the opposite trend for the lifetimes for that system [M. Head-Gordon and J. C. Jully, Chem. Phys. 175, 37 (1993)]. Within an empirical model of nonadiabatic charge transfer [B. N. J. Persson and M. Persson, Solid State Commun. 36, 175 (1980)], our observations can be explained by a decreasing 2π-derived density of states of the Pt/CO complex at the Fermi level.

Vibrational Relaxation of Cyanide on Copper Surfaces: Can Metal d-bands Influence Vibrational Energy Transfer?

“…This type of coupling has been evaluated for the CO/Cu system yielding a lifetime of 8 ps for a 0.2 D dynamic dipole moment 2 . To estimate lifetimes for CN -/ Cu, we scale the result of the CO/Cu calculation with respect to the different dynamic dipole moment values estimated for CN -on metals (0.13-0.16 D) 15 yielding a lifetime of [11][12][13][14][15][16][17][18][19] ps. This estimate is in good agreement with the lifetimes observed for CN -on both polycrystalline Cu and Cu(111).…”

Alignment dependent chemisorption of vibrationally excited CH4(ν3) on Ni(100), Ni(110), and Ni(111)

“…35,36 For the alignment dependent friction argument to be applicable, the rate of vibrational energy transfer between the incident methane molecules and the nickel surface needs to be fast enough for significant vibrational energy transfer to occur on the sub-picosecond timescale of the hyperthermal methane/surface collisions in our experiments. Vibrational lifetimes of strongly bound, chemisorbed species such as CO and CN on transition metals have been measured to be on the order of a few psec by time resolved pump-probe techniques [37][38][39] and lifetimes of physisorbed species can be expected to be significantly longer. Luntz and co-workers did consider the possibility of nonadiabatic effects in adsorption, desorption, and scattering of H 2 (D 2 ) on Cu and N 2 on Ru.…”

Lateral interactions between adsorbed molecules: Investigations of CO on Ru(001) using nonlinear surface vibrational spectroscopies

“…The vibrationally coherent state thus created is probed by detecting the sum-frequency field ( ir ϩ vis ) radiated by the second-order polarization, after an interaction of the surface with a second, nonresonant visible pulse with frequency vis . In the frequency domain, the width of the IV-SFG peak corresponds to the vibrational dephasing constant, whereas the decaying pattern of the time-resolved IV-SFG signal measurement can provide information on the vibrational dephasing rate in the time domain-note that the vibrational population relaxation rate and the pure dephasing rate can be measured by using an IR pump-IR/SFG probe 13,14,19,24 scheme and IR/SFG photonecho techniques, 20 respectively. If the adsorbed molecules undergo a chemical transformation, one can use this method to investigate the real-time chemical reaction dynamics as well as underlying physical processes such as surfacephonon coupling with the adsorbed molecules.…”