Spectra recording

Figure Bl.25.12 illustrates the two scattering modes for a hypothetical adsorption system consisting of an atom on a metal [3]. The stretch vibration of the atom perpendicular to the surface is accompanied by a change m dipole moment the bending mode parallel to the surface is not. As explained above, the EELS spectrum of electrons scattered in the specular direction detects only the dipole-active vibration. The more isotropically scattered electrons, however, undergo impact scattering and excite both vibrational modes. Note that the comparison of EELS spectra recorded in specular and off-specular direction yields infomiation about the orientation of an adsorbed molecule.

Potassium hydrogen monoperoxosulfate monohydrate [14696-73-2] KHSO 20, related to the triple salt, is not made commercially. The crystal stmcture has been determined and some features of its Raman and ir spectra recorded (69). This compound is more stable under x-rays than the triple salt. The 0—0 distance is 0.1460 nm. The dihedral angle of the 0—0 moiety is about 90°, similar to that ia soHd hydrogea peroxide. This compouad is reported as toxic and irritating to eyes, skin, and mucous membranes (2). Although undoubtedly correct, this description probably better relates to the triple salt. 

Amongst miscellaneous UV spectra recorded are those of alkylthio adducts of pyrido[3,2-c]pyridazine (78KGS1272), various pyrido[3,4-d]pyridazines (57AC(R)728) and several vinyl-pyridine-azodicarboxylic ester adducts (79T2027, 79KGS639). 

Fig. 2.14. The C Is XPS spectra recorded by Chin-An Chang et al. [2.68] from perfluoroalkoxy polymer (PFA). (a) before deposition, (b) deposition of copper, (c) deposition of chromium,...

Fig. 2.44. Chemical-bond mapping (a) comparison of EEL spectra recorded from matrix and SiC-fibre with the window for energy filtering shown (b) map of oxidic-bound Si.

Figure 3.10 shows the secondary ion spectra recorded from within the defect and its surroundings. The spectrum from the defective area clearly shows the presence of a polluting perfluorinated polyether structure (the C Fy peaks and the peak at mass 47 amu (CFO" ) are diagnostic of the polyether structure). 

Because of the limited energy resolution in EDX spectra an overlap of peaks can often occur, depending on the composition of the material to be analyzed. The situation is much improved in WDXS, for which the energy resolution is approximately 10 eV and better. This is demonstrated in Fig. 4.25, in which the WDX and EDX spectra recorded from BaTi03 are compared. Here, WDXS enables easy resolution of the Ba-La and Ti-Ka lines this is impossible by EDXS. In addition, for WDXS the... 

Fig. 12.3. NMR spectra recorded during thermal decomposition of dibenzoyl peroxide. Singlet at high field is due to benzene other signals are due to dibenzoyl peroxide. [From H. Fischer and J. Bargon, Acc. Chem. Res. 2 110 (1969). Reproduced by permission of the American Chemical Society.]...

Nitrogen-containing fulvalenes have not been systematically studied by mass spectroscopy. Only isolated data for several examples of compounds have been reported. Most of the data consist of electron impact (El) mass spectra recorded for analytical purposes. Only a minor fraction dealt with the characterization of ion structures or focused on the effects of substituents, the ring size of fulvalenes, or the number and arrangement of nitrogen atoms and the fragmentation pathways. 

Figure 14 Surface IR spectra of etched LDPE-ATR spectra recorded with a KRS-5 reflection element, at 45° angle of incidence. Times refer to chronic acid itch duration. (From Ref. 76.)...

Figure 10-10. (a) Semilogarillnnic plol of ihc stimulated emission transients for various excitation pulse energies measured for LPPP on glass. The excitation pulses have a duration of 150 fs and are centered at 400 nm. The probe pulse were spectrally filtered (Ao=500nin, Aa=l0nm). (b) Emission spectra recorded for the same excitation conditions. The spectra are normalized at the purely electronic emission baud (according lo Ref. [181). 

The XPS S(2p) core level spectra recorded during the stepwise deposition of copper onto poly(3-hcxyllhiophenc), or P3HT [88] are shown in Figure 5-17. The S(2p) spectrum at the lop correspond to the pristine system. On increasim copper... 

Examine the seven absorption spectra, record the Amax values of absorption peaks comment upon the effect of —OH and —NH2 groups upon the absorption spectrum of benzoic acid, and of hydrochloric acid and sodium hydroxide upon the spectra of the two substituted benzoic acids. 

Figure 2.25. C2H4 (a), H2 (b) and C2H6 (c) TPD spectra recorded after ethylene adsorption on clean and K-covered Pt(l 11). Ta = 100 K. 0K values are relative to the saturation K coverage in the first layer taken as unity. Inset effect of 0k on C2H6 TPD area. The real coverage in monolayers (K adatoms per surface atom) is 3.03 times smaller.74 Reprinted with permission from Elsevier Science.

The structure of telomers Tj - T3 is confirmed by NMR spectra recorded for individual compounds. 

The intense yellow rodlike crystals of S14 contain molecules of approximate Cs symmetry on sites of Ci symmetry [165]. Their Raman spectra recorded at -100 °C exhibit the expected pattern Stretching modes give rise to lines between 440 and 485 cm. This rather narrow region reflects the very narrow bond distance distribution in S14 molecules (204.7-206.1 pm). As usual, the bending, torsional and lattice modes show up below 300 cm (see Table 11 and Fig. 26). 

Fig. 12b). Since practically the same spectral shape is obtained at Q-band (35 GHz) (Fig. 12c), the commonly used criterion stating that the shape of an interaction spectrum is frequency-dependent fails to apply in this case. Actually, outer lines arising from the exchange interaction are visible on the spectrum calculated at Q-band (Fig. 12c), but these lines would be hardly detectable in an experimental spectrum, because of their weak intensity and to the small signal-to-noise ratio inherent in Q-band experiments. In these circumstances, spectra recorded at higher frequency would be needed to allow detection and study of the spin-spin interactions. 

Although the n-n and tz-tz electronic transitions of the urea chromophore have not been studied as extensively as amides, the contribution of the backbone is expected to dominate the far UV spectra of oligoureas in a fashion similar to that which is observed for peptides. The CD spectra recorded in MeOH of oligoureas 177 and 178 show an intense maximum near 204 nm (Figure 2.48). This is in contrast to helical y" -peptides that do not exhibit any characteristic CD signature. 

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