X spectra

The structure of IFN-x was also examined by CD [10]. Analysis of the IFN-x spectra predicts that the secondary structural elements derived from CD spectra indicate approximately 70% a-helix. The remainder of the molecule is either predicted to be random or a combination of (3 sheet and turn. Since it is known that algorithms that predict secondary structures from CD spectra are most accurate at identifying a helices, we are confident that IFN-x is mainly a helical. The CD spectra for the synthetic peptides of IFN-x were also obtained. The peptides IFN-x(l-37), IFN-x(62-92), IFN-x(l 19-150), and IFN-x(139-172) all show the presence of a helix, while IFN-x(34-64) and IFN-x(90-122) are mainly random. The presence of an a helix in the peptides supports the CD analysis of the intact protein and also roughly indicates the location of helical segments. 

Isotope spectra. Rotovibrational spectra of deuterium, and of deuterium-rare gas mixtures, have also been recorded over a wide range of temperatures and densities [342]. The differences between the H2-X and D2-X spectra (with X = H2 or D2, respectively, or a rare gas atom) are much like what has been seen above for the rototranslational spectra. 

Interference effects between allowed and induced phenomena have received attention [246], Most of the work reported to date is for liquids and thus outside the scope of this monograph. We mention, though, that the Fano profiles observed in the HD-X spectra, Fig. 3.36, are interesting examples of such interference. 

A further scheme designated specially for observation of satellites in "X spectra relies on the specific shortening of transverse relaxation times T2 for X nuclei adjacent to a quadrupolar nucleus by scalar relaxation of the... 

In B- and AZ-doped FZ silicon samples subjected to NTD, two new EM acceptor spectra are observed after annealing at 500-600° C, besides the above-discussed B-X and Al-X spectra [179]. These spectra, called Bntd and AZntd, are similar to those of the isolated acceptors, but their ionization energies are 28.24 and 43.25meV for Bntd and AZntd, respectively. The ionization energy of Bntd is smaller than the EM energy calculated for acceptors in silicon (31.6 meV) by Baldereschi and Lipari [13]. Such centres have also been... 

The INS spectra of para-H2 in (from top to bottom) zeolites Na-X, Ca-X, Zn-X. Also shown are the spectra decomposed into Gaussians. The Zn-X and the Na-X spectra had their backgrounds removed using a smooth function. These spectra are all measured at low H2 uptakes of around 0.15 wt% [71]. 

Figure Bl.26.17. (a) Observed and calculated ellipsometric [A(X), F(X,)] spectra for the 2 3 vitreous...

Further evidence for the attachment of C-16 to comes from the preparation of the lactam CCCXLVI by Jones oxidation of norfluoro-curine (CCCXXXVIII). This compound, C18H18N2O2, is an Wa-lactam since N- still reacts with methyl iodide. Its IR- (v,1719, -indoxyl, 1668 cm", six-ring lactam) andUV- (A 236, 258, 324, 347 m/x) spectra are close... 

Holloway and Axelson (10) have questioned the superiority of over iH NMR in investigating the stereochemistry of bis-phosphine complexes. In particular in the typical AA X spectra of these systems a triplet ( 3C(X)) will occur in the spectra at much smaller values of Jp-p than it would have in the NMR spectra (where Jp-p > Jp-rr Jp -jf). The authors examined cases of the intermediate Jp-p type ( H NMR) and the NMR spectra obtained showed clean triplets for every carbon to which ip coupling was observable. These examples of cis compounds giving rise to triplets with Jp-p that are not excessively large indicate that NMR spectra of bis-phosphine complexes must be interpreted carefully and that NMR may possess certain drawbacks in stereochemical studies relative to NMR. 

Fig. 48. EPR spectra in Yj j Qdo jBajCujOs j,. (a) Evolution of the 1 ) <-> 1 f) transition as a function of the oxygen content x. Spectra were taken at 9.1 GHz in the temperature range 77-92 K. Lines A, B, D, F and G correspond to well-detemiined CuO chain configurations - i> - 2. nd K, respectively, (b) Concentration dependence of the relative amounts of the local CuO chsun configurations. Open square, open triangle, asterisk, solid triangle, and solid square, represent the 0, 1, 2, 3 and 4 fold occupied configurations, respectively. The calculated intensities are represented by the solid curves (from Pekker et al. 1991, Rockenbauer et al. 1992).

RRS) spectra from trans (1,2) and cis (CH)x (3) and (CD)x have shown that the two isomers present different properties for the electronic excited states and their couplings to the vibrational modes responsible of the light scattering. The main differences in the RRS spectra consist of the long progression of overtones in the spectra of the cis (CH) samples while in the trans (CH)x spectra only the first order processes have been observed and carefully analyzed at least with the laser frequencies used so far (1.65 eV 3.7 eV (4). Broad and weak second order scattering... 

Figure 9.4 shows how the variability s ek) in the X spectra of the calibration set is progressively described by the factors. 

Bush, J., Gilbert, J. and Goenaga, X. Spectra for the identification of monomers in food packaging, Kluwer Academic Publishers, Dordrecht,... 

---