Abstract
A THz-pump and x-ray-probe experiment is simulated where x-ray photoelectron diffraction (XPD) patterns record the coherent vibrational motion of carbon monoxide molecules adsorbed on a Pt(111) surface. Using molecular dynamics simulations, the excitation of frustrated wagging-type motion of the CO molecules by a few-cycle pulse of 2 THz radiation is calculated. From the atomic coordinates, the time-resolved XPD patterns of the C 1s core level photoelectrons are generated. Due to the direct structural information in these data provided by the forward scattering maximum along the carbon-oxygen direction, the sequence of these patterns represents the equivalent of a molecular movie.
Highlights
Pump-probe experiments have brought about the field of femtochemistry1 where the molecular dynamics in chemical reactions is studied in real time
Experiments measuring the dynamics of the nuclear coordinates on surfaces directly via time-resolved diffraction methods have remained scarce,11 which reflects the difficulty of obtaining such data on a femtosecond time scale
An example of a molecular movie is presented in which molecular motion can be followed in real time and with atomic resolution
Summary
Pump-probe experiments have brought about the field of femtochemistry where the molecular dynamics in chemical reactions is studied in real time. An ultrashort pump pulse of laser light triggers some process in a molecule, while a probe pulse of electrons or electromagnetic radiation records the transient structural changes either directly in the nuclear coordinates or indirectly via the electronic or vibrational properties of the system after a defined delay on the femtosecond time scale. Pulsed electron and x-ray diffraction have been successfully used as time-resolved direct structural probes for molecules in the gas phase.. Experiments measuring the dynamics of the nuclear coordinates on surfaces directly via time-resolved diffraction methods have remained scarce, which reflects the difficulty of obtaining such data on a femtosecond time scale Bond weakening and bond breaking processes have been followed by time-resolved non-linear optical methods and by time-resolved two-photon photoemission. More recently, the advent of x-ray free-electron lasers (XFEL) has made it possible to observe bond breaking and bond formation on surfaces via x-ray absorption and x-ray emission experiments. On the other hand, experiments measuring the dynamics of the nuclear coordinates on surfaces directly via time-resolved diffraction methods have remained scarce, which reflects the difficulty of obtaining such data on a femtosecond time scale
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
