Sn Spectra

St - Sn Spectra.—A description has been given of a method for recording ultrafast absorption spectra using a passively mode-locked ruby laser with a ruby amplifier, a pulsed flashlamp probe source, and streak-camera detection for ps time resolution. Results for the dye 3,3 -diethylthiatricarbocyanine in methanol were reported.2870 These results can be compared with those obtained by an alternative method 29711 which permits nm spectral resolution and ps time resolution over the entire visible region, and which was first used on the Sx - Sn absorption of 3,3 -diethyloxadicarbocyanine iodide, and which has recently been used to record the Si - Sn absorption spectra of bis-(4-dimethylaminodithio-benzil) nickel(n), and of SnIV, Pd11, and Cu porphyrins.298 The use of time-resolved Si - Sn, Ti - Tn absorption and emission spectroscopy to assist in the selection of laser dyes has been illustrated with respect to anthracene and its derivatives.299 Si - Sn Spectra of coronene, 1 2-benzanthracene, l 12-benz-perylene, 1,2,3,4-dibenzanthracene, and benzo[6]chrysene in poly(methyl methacrylate) and toluene have been reported, the method of detection being modulation spectrophotometry, for which it is claimed that species of lifetime down to 

51 state to change its conformation in the fluid medium,164 but not in the solid. 

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Depending on the matrix and the post-ionization technique, SN" spectra can be dominated by atomic or molecular signals. In particular, compounds with high mass... 

Solvent Effects in the Sn Spectra of Poly(TBTM/MMA). Samples of poly(MMA/TBTM) synthesized by the free-radical copolymerization of the appropriate monomers were solutions in benzene with approximately 33% solids (weight to volume). The particular formulation chosen as representative of the class contained a 1 1 ratio of pendant methyl to tri-n-butyltin groups. In preparing the dry polymer, the benzene was removed in vacuo with nominally 5% by weight residual solvent. 

The Sn spectra of the polymer in methanol, n-butanol, and i-proganol shows broadening of the Sn signal, and the 3j(H Sn, C) values both increase in the order i-propanol < n-butanol < methanol. Both the appearance and the position of the l Sn signal in donating solvents can be attributed to the ability of the solvent to coordinate with tin. 

SnXe] " ions. Values of 5" Sn shift to lower frequencies in passing from tetrahedral to trigonal bipyramidal to octahedral symmetries. Some representative solution values for 5" Sn are given in Table 7. Solid-state 5 Sn spectra are being increasingly reported. Comparison of sohd-state and solution spectra can point out structural differences in the two phases. 

The two metal nuclei that can be studied by Mdssbauer spectroscopy and are relevant to metallocenes are Fe and " Sn. Spectra from both nuclei have been used to examine the electronic effects of substitution on metallocenes. 

The " Sn NMR spectra confirm the observations made for the highly populated species M. H and Sn spectra reveal identical patterns in C6D6 and CDCI3 and display strong but perfectly reversible temperature dependence (Figures 15a to 15c). 

Fig. 13. (left) " Sn spectra of Sm2Sn2O7 at four different temperatures, (right) Temperature dependence of the isotropic resonance. The estimated crossover temperature is 600 K. (Figures from refs. 169 and 180, Copyright 1995 by Academic Press, reproduced by permission of the publisher.)... 

Fig. 14.8 Sn spectra and simulated curves for (A) SnS at 4-2 K with a field of 50 kG applied perpendicular to the axis of observation, and (B) SnC204 under the same conditions. [Ref. 52]...

EuSna and EuSn both show a magnetic interaction at 4 2 K, but more information comes from the Sn spectra which show two distinct tin sites in EuSna [56]. 

Besides oxide supported Sn-Ru catalysts, carbon supported catalysts also find application in hydrogenation reactions. Sn Mossbauer spectroscopy was used to investigate the tin component of ruthenium and tin supported on activated carbon catalysts containing 2 wt. % ruthenium and having Sn/(Sn-f Ru) ratios between zero and 0.4. Four major components in the Sn Mossbauer spectra were attributed to both Sn(II) and Sn(IV) oxides and to Ru-SnOx species formed on the surface of ruthenium metal particles. In addition to this " Sn spectra reveal the presence of minor amounts of Ru3Sn7 alloy phase. ... 

Figure 7. High-resolution XPS Sn spectra for (a) the joint after 30-min Ar+ etching, (b) Sn02 and (c) Sn metal. (Reproduced from Ref. 8, by permission of El.sevier Science. Amsterdam.)...

Because of the low natural abundance of Si, molecules containing more than one type of silicon do not give splittings due to (Si,Si) coupling on the principal peaks. However, "satellite resonances can sometimes be detected (3,18,19), and yield values of dgiSi Such homonuclear satellite resonances are, of course, more pronounced for Sn and Pb in suitable molecules. For tin, double satellite resonances appear because of the existence of both Sn and Sn in comparable natural abundance. Whereas the satellites in Sn due to the presence of Sn are normally (but not always (20)) first order, the Sn satellites in Sn spectra are often second order. 

In observing the nuclear magnetic resonance of the tin isotope atoms, however, the ii Sn isotope is both slightly more sensitive to detection, and is also the most abundant isotope. Thus it is usual to observe the n Sn spectra in nuclear magnetic resonance investigations on tin. 

Most Mdssbauer measurements of ii9 Sn spectra are taken at very low temperature, but it has been noted that six-coordination of tin is usually accompanied by the presence of a measurably large resonance at ordinary temperatures. ... 

Fig. 5.3 XPS spectra of the pure and Ni-doped Cu2ZnSnS4 nanocrystals, a Cu spectra, b Zn spectra, c Sn spectra, d S spectra, and e Ni spectra...

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