Structural dynamics of a catalytic monolayer probed by ultrafast 2D IR vibrational echoes.
Ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy has proven broadly useful for studying molecular dynamics in solutions. Here, we extend the technique to probing the interfacial dynamics and structure of a silica surface-tethered transition metal carbonyl complex--tricarbonyl (1,10-phenanthroline)rhenium chloride--of interest as a photoreduction catalyst. We interpret the data using a theoretical framework devised to separate the roles of structural evolution and excitation transfer in inducing spectral diffusion. The structural dynamics, as reported on by a carbonyl stretch vibration of the surface-bound complex, have a characteristic time of ~150 picoseconds in the absence of solvent, decrease in duration by a factor of three upon addition of chloroform, and decrease another order of magnitude for the bulk solution. Conversely, solvent-complex interactions increase the lifetime of the probed vibration by 160% when solvent is applied to the monolayer.
Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
Daniel E
DE
Rosenfeld
Zsolt
Z
Gengeliczki
Brian J
BJ
Smith
T D P
TD
Stack
M D
MD
Fayer
D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D010100:Oxygen / Q000737:chemistry; D012822:Silicon Dioxide; D013055:Spectrophotometry, Infrared / Q000379:methods*
D002244:Carbon; D012822:Silicon Dioxide; D010100:Oxygen