Changes in the fingerprint region

Changes in the fingerprint region of the spectra can also be related to surfactant penetration. The frequency and shape of the 8, CH2 band are very sensitive to intrachain interactions The CH2 wagging defect modes and the C-0 bands of the surfactant appear in this region as well. 

The changes in the fingerprint region, Figure 3.17(b), are more complex due to the overlapping bands, some of which broaden and shift due to the increase in polarity of the network as curing takes place. In spite of this it is possible to discern two amine-related... 

Recently, the excited state characteristics of HPTS have been probed with mid-infrared pulses providing insight into state-specific vibrational modes [76]. In Fig. 14.3 the absorbance changes in the fingerprint region of HPTS are shown to be solvent dependent. The fact that these vibrational band patterns appear within the time resolution of 150 fs, without any additional changes up to several tens of picoseconds, indicates that previous observations of a 2.5 ps time component in UV/vis pump-probe experiments [59, 60] previously assigned to a iL], —> level... 

The MonARC FTIR system from Mettler Toledo identifies and quantifies chemical species based on changes in the fingerprint region of their IR spectrum. It also has a built-in ultrasonic cleaner for the diamond sensor which increases reproducibility and reduces downtime. Various types of fibre optic cable and probe heads are available depending on... 

The soft-mode absorption of cyclohexane on the stepped Ni[5(lll) X (110)] surface is clearly present at ca. 2620 cm, but with much reduced intensity compared with that on Ni(lll) (7), implying, as expected, less convenient CH contacts with the metal surface. The band positions in the fingerprint region are similar, but notable changes in relative intensities, e.g., of the prominent ca. 520-cm 1 absorption, suggest a nonparallel orientation with respect to the surface. Indeed the on-specular spectrum of the species on Ni[5(l 11) X (110)] bears a remarkable resemblance to the off-specular spectrum of the species on Pt(lll) (222) whereby the modes with dipole changes parallel to the surface, i.e., parallel to the median Q, plane,... 

Headgroup Modes. Additional information about the changes in molecular packing with compositional changes can be obtained from inspection of the spectra in the fingerprint region. Figure 15 shows the spectra of the various mixtures. 

Besides TRIR, it is also possible to employ excited-state resonance Raman spectroscopy (TR or TR2) to characterize excited-states of [Re(L)(CO)3(N,N)] 1 complexes [25, 27, 37, 48, 79, 81, 82], The spectra show bands due to vibrations of the N,N ligand and provide information on its structural changes upon excitation. Picosecond TR3 spectra of Re complexes give very weak signals [37], Measurements on the ns timescale are more informative. In the case of CT and TL states of [Re(py) (CO)3(dppz)]+ and the 3LLCT state of [Re(py-azacrown)(CO)3(bpy)]+ [16, 27], complementary vibrational information was provided by TR3 and TRIR measured in the fingerprint region. 

With the high spatial resolution of the synchrotron, individual cells within a tissue can be probed with subcellular resoluhon. For example, the structures of misfolded protein aggregates in neurological protein folding diseases have been identified in the brain tissue of Alzheimer s disease patients [31-33], while infectious prion proteins have been characterized in scrapie [34-37]. Additional biochemical changes have also been observed in the fingerprint regions of Alzheimer s [38], Parkinson s [39] and scrapie-infected tissues [40]. 

The root mean square (RMS) error between two spectra reacts more sensitively to global intensity differences and small changes, for instance, in the fingerprint region. 

A. These are present in ethers, alcohols, esters, anhydrides, and carboxylic acids. Their bands occur in the fingerprint region (usually between 1250 and 1000 cm ) and are subject to erratic shifts from quite small structural changes. Fortunately they are very intense in the IR, which usually enables them to be identified. They are useful for confirming an ester, deciding on the type of ether or alcohol, or suggesting a ketone (by their absence). 

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