In situ IRRAS

Fig. 9.8 Optical setup for in-situ IRRAS based on the following windows (a) Cap2 equilateral prism (transmission range 76900-1100 cm" RAir/CaF,=0-03), (b) ZnSe hemisphere (transmission range 22200-700 cm" RAir/znSe=0-18).

Thus, for both metallic and transparent snbstrates, p-polarization, angles of incidence above cpc, and water layers thinner than 1-2 p,m are preferable. Under these conditions (p > (pc and t/2 < dp, where dp is the penetration depth), the cell windows act as IREs. In other words, the in situ IRRAS geometry under the optimum conditions is in fact the ATR geometry in Otto s configuration (Fig. 236d). 

The above example demonstrates that interference with the solution spectrum can be reduced considerably by use of an appropriate buffer that has high concentration of coadsorbed species and no absorption bands in the spectral region under study (see also Refs. [154, 155]). The solution bands can be distinguished in /7-polarized in situ IRRAS by comparison with the Y-polarized spectra in which only the absorption bands of the species in solution are present (Section 1.8.2). However, since the SSR holds at a distance of 1 p,m out into the solution from the metal surface, this approach can be inefficient. In this case, apart from using other means (vide infra), one can resolve the contribution of bulk solution comparing the dependence of s- and /7-polarized spectra on the buffer concentration [156]. Comparison with the reference spectra of the electrolyte... 

Figure 3.46. In situ IRRAS of poly-(3-methyl thiophene)(CI04 ) film in BU4NCIO4 in acetonitrile at -F0.35 V (with offset of -0.1 reflectance units) and poly-(3-methyl thiophene)(PF6 ) film in BU4NPF6 in acetonitrile at -1-0.65 V. Reference spectrum recorded at -0.35 V. Spectra were recorded using Bruker IFS-113V FTIR spectrometer with MCT detector. Spectral resolution was 4 cm and number of scans for each spectrum was 128. Reprinted, by permission, from E. Lankinen, G. Sundholm, P. Talonen, T. Laltinen, and T. Saario, J. Electroanal. Chem. 447, 135-145 (1998), p. 141, Fig. 6. Copyright 1998 Elsevier Science B.V.

Yakovlev and coworkers [402a, 402b] reported the IR absorption enhancement by mote than one order of magnitude for hydrocarbons adsorbed inside porous silicon, and assigned this effect to photon confinement in the microcavity acting like a multipass (Fabry-Perot type) cell. Recently, Jiang et al. [402c] observed a 50 times enhancement in the in situ IRRAS of CO adsorbed on Pd nanoparticles synthesized in cavities of Y-zeolite, as compared to the cases when the supports were ultrathin Pd films deposited directly on the zeolite or on amorphous alumosiUcate layer. 

Figure 4.42. Physical vacuum deposition apparatus for real-time in situ IRRAS measurements (a) substrate (b) thickness monitor (c) ZnSe windows (d) IR beam (e) shutter (f) mercury lamp (g) crucible. Reprinted, by permission, from M. Tamada, H. Koshikawa, and H. Omichi, Thin Solid Films 292,164-168 (1997), p. 165, Fig. 1. Copyright 1997 Elsevier Science S.A.

SNIFTIRS is able to provide detection limits for in situ IRRAS of 10 -10 " AE/E with a spectral resolution of 8-16 cm" and several hours of data collection [361]. In general, application of this technique is restricted to reversible electrochemical systems. However, flow cell tactics enable one to utilize this method even when examining irreversible Faradaic processes if the... 

Figure 4.53. In situ IRRAS spectra of SCN adsorbed on Cu electrode (a) PM and p) ordinary SPAIRS spectra. Reference is—1.2 V (Ag-AgCI)and sample potentials are marked. Experiments were performed on Mattson RS-1 spectrometer configured with external bench analogous to that shown in Fig. 4.51. Photoelastic modulator was Flinds International ZnSe Series II modulator, operating at 37 kFIz. The PM wavefront was sampled in real time with ATI Instruments real-time sampling accessory. The MCT detector with D of 5 x 10 ° cm W was used. Spectra are represented in absorption depth of PM signal (Aflpm). Reprinted, by permission, from W. N. Richmond, P. W. Faguy, R. S. Jackson, and S. C. Weibel, Anal. Chem 68, 621 (1996), p. 625. Copyright 1996 American Chemical Society.

In situ IRRAS. ATR in Otto s geometry (Section 2.5.4) was applied to the EX-chalcocite system in 13-reflection geometry [330]. The main advantage of... 

In situ IRRAS with a Ge prism window was used by Laajalehto et al. [603] to study the effect of pyrite activation by copper and lead ions at pH 5, 6.5, and 9. It was found that the xanthate interaction with copper-activated pyrite resembles that of chalcopyrite, resulting in adsorption and dixanthogen formation. In similar experiments with lead-activated pyrite, only very weak absorption bands of the adsorbed collector were observed, implying that lead depresses rather than activates pyrite. 

HOO" (H2O2) on Ti02 in situ IRRAS [655] Water in primary hydration sphere of Li+ in DL in situ IRRAS [156b]... 

Fig. 1.12 In situ IRRAS spectra recorded during EOR on three MM7Sn02/C NP electrocatalysts (a) Ptlr/Sn02/C, (b) PtRhi/3/Sn02/C, and (c) PtIrRh/Sn02/C [112]...

Liao, K., Du, X., 2009. In situ IRRAS studies of NH stretching bands and molecular structures of the monolayers of amphiphiles containing amide and amine units at the air—water interface. J. Phys. Chem. B 113, 1396-1403. 

Electrocatalysis of Anodic Reactions, Fig. 2 In situ IRRAS spectra recorded during the EOR on the RhSn02/ Pt(lll) consisting of clusters equivalent to 2ML of Sn02 and 0.5ML Rh on a Pt(lll) electrode surface (a), and... 

Figure 32 In situ IRRA difference spectra revealing the structure of the subsequently deposited three layers of HMDS plasma polymer on plasma-oxidized iron. The polymer was deposited at a partial pressure of Phmds value d means the thickness of...

---