Subtractively normalized interfacial spectroscopy

QCMB RAM SBR SEI SEM SERS SFL SHE SLI SNIFTIRS quartz crystal microbalance rechargeable alkaline manganese dioxide-zinc styrene-butadiene rubber solid electrolyte interphase scanning electron microscopy surface enhanced Raman spectroscopy sulfolane-based electrolyte standard hydrogen electrode starter-light-ignition subtractively normalized interfacial Fourier transform infrared... 

It is only since 1980 that in situ spectroscopic techniques have been developed to obtain identification of the adsorbed intermediates and hence of reliable reaction mechanisms. These new infrared spectroscopic in situ techniques, such as electrochemically modulated infrared reflectance spectroscopy (EMIRS), which uses a dispersive spectrometer, Fourier transform infrared reflectance spectroscopy, or a subtractively normalized interfacial Fourier transform infrared reflectance spectroscopy (SNIFTIRS), have provided definitive proof for the presence of strongly adsorbed species (mainly adsorbed carbon monoxide) acting as catalytic poisons. " " Even though this chapter is not devoted to the description of in situ infrared techniques, it is useful to briefly note the advantages and limitations of such spectroscopic methods. 

SNIFTIRS subtractively normalized interfacial Eourier transform infrared spectroscopy... 

Figure 6.18 Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) spectra of a polished polyciystaUine Pt electrode, immersed in 0.1 M HCIO4, + 5 M CH3OH electrolyte. All spectra were normahzed to the base spectrum collected at 0 mV vs. RHE. (Reproduced from Iwasita and Vielstich [1988].)...

Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS), has been used extensively to examine interactions of species at the electrode/electrolyte interface. In the present work, the method has been extended to probe interactions at the mercury solution interface. The diminished potential dependent frequency shifts of species adsorbed at mercury electrodes are compared with shifts observed for similar species adsorbed at d-band metals. 

Subtractively normalized interfacial Fourier transform infrared spectroscopy has been used to follow the reorientations of isoquinoline molecules adsorbed at a mercury electrode. Field induced infrared absorption is a major contribution to the intensities of the vibrational band structure of aromatic organic molecules adsorbed on mercury. Adsorbed isoquinoline was observed to go through an abrupt reorientation at potentials more negative than about -0.73 V vs SCE (the actual transition potential being dependent on the bulk solution concentration) to the vertical 6,7 position. 

The SNIFTIRS approach. The acronym SNIFTIRS means Subtractively Normalized Interfacial Fourier Transform Infrared Spectroscopy. The basic concept of this method involves the fact that the raw data obtained directly from the Fourier Transform process contain components which are undesirable. Firstly, there is material in the solution which may have affected the spectrum. Secondly, unwanted information on certain material on the electrode (adsorbed water, for example) is best eliminated. 

Hamelin [47] has shown that specific adsorption of OH ions increases in the following order Au(lll) < Au(lOO) < Au(311). Chen and Lipkowski [48] have applied chronocoulometry and subtractively normalized interfacial Fourier transform infrared spectroscopy to study adsorption of hydroxide ions on Au(lll) electrode. This process proceeded in three steps. Bonding of OH with gold atoms that is quite polar at negatively charged surface becomes less polar at positively... 

In situ subtractively normalized interfacial FTIR spectroscopy has been employed [254] to study adsorption of pyridine on the Au(llO) electrode surface. The compound adsorbed via the nitrogen atom and the tilting angle decreased progressively with the increasing electrode potential, as it appeared from the IR data. 

Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTRS). Using an FTIR spectrometer, multifrequency... 

In situ IR spectra were recorded using, either the Single Potential Alteration Iirfrared Reflectance Spectroscopy (SPAIRS), also called Linear Potential Sweep-Fourier Transform Infrared Reflectance Spectroscopy (LPS-FTIRS), or the Subtractively Normalized Interfacial Fourier Transform Infrared Reflectance Spectroscopy (SNIFTIRS). ... 

CO adsorption on Cu electrode surface is interfered with by specifically adsorbed anions. CO can be adsorbed below a certain definite potential, determined by the adsorption strength of CO and the anion. When CO molecules displace the specifically adsorbed anions on Cu electrode, a voltammetric peak is observed as exemplified for Cu(lOO) in CO saturated phosphate buffer solution in comparison with N2 saturated solution (Fig. 29). Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) spectra in Fig. 30 demonstrates that CO is adsorbed at -0.8 V vs. SHE but not at -0.4 V, and adsorbed phosphate anion vice versa. " This process is equivalent to charge displacement adsorption of CO on Pt electrode revealed by Clavilier et al The profile of the voltammogram depends greatly on the crystal... 

Pons [133] reported a slightly more sophisticated data acquisition protocol, which he termed SNIFTIRS (subtractively normalized interfacial Fourier transform infrared spectroscopy), which involved stepping the potential of the reflective working electrode repeatedly between two preset values, as shown in Fig. 11(d). The... 

SNIETIRS subtractively normalized interfacial ETIR spectroscopy... 

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