New Approach to Simultaneous In Situ Measurements of the Air/Liquid/Solid Interface Using PM-IRRAS

Abstract

Vibrational spectroscopy techniques have evolved to measure gases, liquids, and solids at surfaces and interfaces. In the field of surface-sensitive vibrational spectroscopy, infrared spectroscopy measures the adsorption on surfaces and changes from reactions. Previous polarized modulated-infrared reflection− absorption spectroscopy (PM-IRRAS) measurements at the gas/ solid interface were developed to observe catalytic reactions near reaction conditions. Other PM-IRRAS measurements use liquid cells where the sample is submerged and compressed against a prism that has traditionally been used for electrochemical reactions. This article presents a new method that is used to observe in situ adsorption of molecules using PM-IRRAS at the gas/liquid/solid interface. We demonstrate the meniscus method by measuring the adsorption of octadecanethiol on gold surfaces. Characterization of self-assembled monolayers (SAMs), the "gold standard" for PM-IRRAS calibration measurements, was measured in ethanol solutions. The condensed-phase (air/liquid) interface in addition to the liquid/solid interface was measured simultaneously in solution. These are compared with liquid attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy measurements to confirm the presence of the SAM and liquid ethanol. A model of the three-phase system is used to approximate the thickness of the liquid ethanol layer and correlate these values to signal attenuation using PM-IRRAS. This proof-of-concept study enables the measurement of reactions at the gas/liquid/solid interface that could be adapted for other reactions at the electrode and electrolyte interfaces with applications in environmental science and heterogeneous catalysis.

Shell–Matrix Interaction in Nanoparticle-Imprinted Matrices: Implications for Selective Nanoparticle Detection and Separation

“…This challenge was addressed by employing a highly surface-sensitive spectroscopy method attempting to reveal the different chemical interactions between the AuNPs and the matrix. Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) is a vibrational technique that enables the detection of chemical functionalities and their orientation at submonolayer coverage. , Since PM-IRRAS requires a reflective surface (ideally Au surface), the ITO electrode was replaced by a flame-annealed Au electrode. The imprinting process was identical to that performed for ITO, and as seen previously, it did not alter the final composition or morphology of the electropolymerized layer.…”

Effect of Cations on the Oxidation and Atmospheric Corrosion of Iron Interfaces to Minerals

“…An iS50R Fourier transform infrared spectrometer (Thermo Scientific, Inc.) instrument with aluminum mirrors was used to collect PM-IRRAS infrared reflectance absorbance spectra and ATR–FTIR spectra of the samples. An in-house built (by the Perrine research group) optical set up was coupled to the same instrument to collect PM-IRRAS, as described previously. , The polished iron samples were attached to the sample holder in a vertical orientation, as shown in Figure A. A photoelastic modulator (PEM, Hinds, Inc.) with a ZnSe polarizer was placed in the beam path to modulate the signal between p and s polarized light.…”

“…The optical alignment onto the iron surface and the optimization of the peak-to-peak (p/p) signal were carried out as described previously. , Several types of spectra were collected under the different stages of corrosion of iron with either 10 mM CaCl 2 (aq) or 10 mM NaCl­(aq) electrolytes. First, a spectrum of the dry, polished iron sample was collected before starting the corrosion reaction.…”

“…An in-house built (by the Perrine research group) optical set up was coupled to the same instrument to collect PM-IRRAS, as described previously. 13,35 The polished iron samples were attached to the sample holder in a vertical orientation, as shown in Figure 1A. A photoelastic modulator (PEM, Hinds, Inc.) with a ZnSe polarizer was placed in the beam path to modulate the signal between p and s polarized light.…”

The greenest solar power? Life cycle assessment of foam-based flexible floatovoltaics

“…An iS50R (Thermo Scientific) Fourier transform infrared (FTIR) spectrometer was used for the analysis and was calibrated with the following parameters: 256 scans, 4 cm −1 resolution, and a wavenumber bandwidth of 4000–650 cm −1 . 76,77 The resulting spectra were compared to possible matches in the iS50R software database. The front transparent layer belongs to the polyurethane rubber family and the back white layer was identified as polyethylene terephthalate (PET) polymer as displayed in Fig.…”