Ultrafast Transient Dynamics of Adsorbates on Surfaces Deciphered: The Case of CO on Cu(100)

D Novko,J C Tremblay,J I Juaristi,M Alducin

doi:10.1103/physrevlett.122.016806

Abstract

Time-resolved vibrational spectroscopy constitutes an invaluable experimental tool for monitoring hot-carrier-induced surface reactions. However, the absence of a full understanding of the precise microscopic mechanisms causing the transient spectral changes has limited its applicability. Here we introduce a robust first-principles theoretical framework that successfully explains both the nonthermal frequency and linewidth changes of the CO internal stretch mode on Cu(100) induced by femtosecond laser pulses. Two distinct processes engender the changes: electron-hole pair excitations underlie the nonthermal frequency shifts, while electron-mediated vibrational mode coupling gives rise to linewidth changes. Furthermore, the origin and precise sequence of coupling events are finally identified.

Highlights

One of the ultimate goals in surface science is to comprehend the fundamental processes that bring about the specific timescales of surface reactions [1,2,3]
In time-resolved infrared (IR) spectroscopy experiments, the initial adsorbate dynamics commenced by the pump pulse is directly probed by tracking the frequency shift and linewidth changes of the IR-active internal stretch (IS) mode
The lack of a general quantitative theory effectively prevents us from harnessing the full potential of time-resolved vibrational spectroscopy, as well as from extracting the information about subpicosecond dynamics of surface reactions buried within

Summary

Introduction

One of the ultimate goals in surface science is to comprehend the fundamental processes that bring about the specific timescales of surface reactions [1,2,3]. Two distinct processes engender the changes: electron-hole pair excitations underlie the nonthermal frequency shifts, while electron-mediated vibrational mode coupling gives rise to linewidth changes.

Results

Conclusion