Abstract: Electrochemical in situ step-scan time-resolved microscope FTIR spectroscopy (in situ SS-TR-MFTIRS) was successively established, for the first time in the present work, by using a step-scan FTIR instrument (Nexus 870 FTIR spectrometer) and an IR microscope (IR-plane advantage microscope). A homemade signal synchronizer was used to generate polarization potential that is in accordance with the signal-time-sequence of step-scan time-resolved spectral data collection. Due to the use of a nanostructured microelectrode of Pt and the enhancement of IR absorption, a character of abnormal infrared effects of the nanostructured Pt surface, IR determination sensitivity of surface species was significantly increased, and the rate of responding to a polarizing potential of electrode surface in a thin-layer IR cell was remarkably improved. Adsorption of CO on nanostructured Pt microelectrode(Φ=0.2 mm)in sulfuric acid solutions was investigated by using the present new technique, and a spectral time-resolution as fast as 50 μs has been achieved. From the variation versus t of the band center of linear-bonded CO(see Fig.7) that is measured from in situ SS-TR-MFTIR spectra, the cell constant (τ=R1Cd) of an electrochemical thin-layer IR cell of external reflection mode, which is employed widely in studies of electrochemical in situ IR spectroscopy, has been determined to be 0.65 ms. In comparison with the τ of 40 ms for a conventional Pt disk electrode (Φ=6.0 mm),the use of a Pt microelectrode has reduced dramatically the thin-layer IR cell constant to about 61 times. The results obtained in the current paper is of importance in illustrating the success of establishing the in situ SS-TR-MFTIRS, and demonstrating the powerful capability of the in situ SS-TR-MFTIRS for studies of fast dynamic processes of electrode and kinetics of reactions taking place at solid/liquid interfaces as well.

Key words: Step-scan, Time-resolved IR spectroscopy, IR microscope, Pt microelectrode, CO adsorption