Step-scan Microsecond Time-resolved FT-IR Measurements

Step-scan Microsecond Time-resolved FT-IR Measurements 

If the system to be examined is reversible or repeatable, much faster time resolutions are achieved by using a step-scan FT-IR spectrometer [129]. The interferometer is moved stepwise in the step-scan mode as shown in Fig. 8.27 (left). When the moving mirror of the interferometer is fixed at a position (i.e., at a 

As an example of step-scan time-resolved FT-IR measurement, the study of the dissolution dynamics of an underpotentially deposited (UPD) Cu layer on an Au(lll) electrode is shown in Fig. 8.28 [130]. The set of 1-ms time-resolved spectra for a potential step from 0.1 to 0.3 V (vs SCE) represents the desorption of sulfate species coadsorbed with UPD Cu (the band at 1214 cm ). The transient of the intensity of the v(S-O) band of the sulfate species is plotted in Fig. 8.29 b as a function of time. The corresponding current transient data is shown in Fig. 8.29 a. The intensity data were fitted with a general rate equation 

50 ps and (b) 10 s. Solid curves in (a) represent the fittings with Langmuir kinetics ( = 1) and spontaneous and progressive nucleation-and-growth kinetics ( = 2 and 3, respectively) [14]. 

Sub-millisecond time-resolved SEIRAS has also been applied for other dynamic processes such as the redox reactions of heptylviologen on Ag [12], adsorption/desorption of fumaric acid [13] on Au and sulfate on Ag [16], and phase transitions in uracil adlayers on Au [15]. In the latter two studies, discrepancies between the time-resolved IR and chronoamperometry were suggested. 

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