Surfaces FTIR imaging

The goal of our investigations was to characterise the morphology of the sample, and to determine the size and location of the PTFE and silicone oil phases by different methods [46,47], For phase characterization using Raman microscopy, no special sample preparation was necessary. For FTIR imaging, microtomed sections (5 pm in thickness) had to be prepared by cutting the sample with a diamond knife at — 80°C ("cryo-microtomy") to prevent smearing and to obtain flat surfaces. 

Fourier-Transform Infrared (FTIR) spectroscopy as well as Raman spectroscopy are well established as methods for structural analysis of compounds in solution or when adsorbed to surfaces or in any other state. Analysis of the spectra provides information of qualitative as well as of quantitative nature. Very recent developments, FTIR imaging spectroscopy as well as Raman mapping spectroscopy, provide important information leading to the development of novel materials. If applied under optical near-field conditions, these new technologies combine lateral resolution down to the size of nanoparticles with the high chemical selectivity of a FTIR or Raman spectrum. These techniques now help us obtain information on molecular order and molecular orientation and conformation [1],... 

Figure 10.19 FTIR imaging system. Left, an optical pathway in an IR microscope associated with a spectrometer. The sample can he examined in transmission (left), or in specular reflection modes (right). This accessory is installed in a spectrometer whose beam is deflected. The Cassegrain optic has the advantage that the light is reflected at the surface of mirrors rather than having to pass through optical lenses. Right, model 400 UMA (reproduced courtesy of Varian Inc. USA).

Holman HY, Perry DL, Martin MC, Lamble GM, McKinney WR, Hunter-Cevera JC, (1999) Real-time characterization of biogeochemical reduction of Cr(VI) on basalt surfaces by SR-FTIR imaging. 

Figure 5.4 Photomicrographs of formalin-fixed prostate cancer cells, (A) without subsequent rinsing in deionized water and (B) with 3 s rinse in deionized water to remove residual PBS from the surface of the cells. Scale bar in all photomicrographs = 50 pm. (C) Optical image of a single, formalin-fixed, PC-3 cell. The cell s nucleus and nucleolus (N) are identified. SR-FTIR images depicting the intensity profiles of lipid ester v/C=0) (1752-1722 cm peak area) and phosphate v /P02) (1280-1174 cm peak area). (D) The FTIR spectrum of formalin and overlay of the FTIR spectrum of the cytoplasm with the same spectrum processed to remove their theoretical formalin content. (Reproduced from reference [48].)...

The shift of the amide I mode (FTIR spectra) from 1657 to 1646 cm-1 was attributed to a change in the a-helix native structure to fl-sheets, secondary structure conformations. Atomic Force Microscopy (AFM) images display the coating of the manganese oxide surface as well as the unfolding in a ellipsoidal chain of the protein molecules after adsorption and immobilization on the surface. 

Fig. 8.1. Field ionization of a hydrogen atom (H). (a) close to a tungsten surface (W), (b) isolated. Conditions and symbols electric field 2 V A Pw image potential of W distorted by the field, Ph potential of the hydrogen atom distorted by the field, X work function, p Fermi level. Broken lines represent potentials in absence of the electric field. Adapted from Ref. [4] by permission. Verlag der Zeitschrift ftir Naturforschung, 1955.

Figure 3.18. Thin TTF-TCNQ film (thickness 1 um) HV-grown on a KCl(lOO) substrate, (a) Topography and (b) amplitude TMAFM images. The scale is 5 p.m x 5 ]xm. (c) FTIR spectra of the CN stretching mode in neutral TCNQ (powder) and in a TTF-TCNQ thin film (thickness 1 um) HV-grown on KBr(lOO). Reprinted from Surface Science, Vol. 482 85, C. Rojas, J. Caro, M. Grioni and J. Fraxedas, Surface characterization of metallic molecular organic thin films tetrathiaful-valene tetracyanoquinodimethane, 546-551, Copyright (2001), with permission from Elsevier.

Microstructuring of the surface of a polymer membrane on solid support is commonly performed by various lithographic techniques. In previous applications is was not necessary or it was not tested whether the microstructured pores extend down to the neat support surface or whether the lower part of the pore remains filled with bulk polymer of with residues of the lithographic process. It could be shown by FTIR spectroscopic imaging for the first time, that residues remain inside the pores, which chemical origin the residues have and how the microstructuring process can be optimized towards completely empty pores, even if the diameter of the pores does not exceed a couple of micrometers. 

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