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H. -A. Fabricius E. Köttgen R. Stahn W. Brummer und J. Laititis 《Fresenius' Journal of Analytical Chemistry》1982,311(4):354-355
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New diagnostic possibilities in analysis of cellular immune functions in vitro相似文献
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Absorption spectra (77 and 298 K), luminescence spectra (5-80 K), and luminescence lifetimes (5-80 K) for the title complexes have been correlated to increasing diphosphine basicity (R = 4-CF(3)-Ph < 4-H-Ph < 4-CH(3)O-Ph < Et). As a consequence, spectral peaks have been assigned to (1,3)MLCT (B(1u), W --> phosphorus) and (1,3)LF (B(2g)) terms. As the ligand basicity increases, the (3)MLCT bands observed in absorption blue-shift nearly 8000 cm(-1) and the vibrationally structured (3)LF bands observed in emission red-shift approximately 1300 cm(-1). (3)LF terms lie lowest in energy in the 4-H-Ph, 4-CH(3)O-Ph, and Et compounds, and temperature-dependent lifetime data suggest emission from each be assigned to the equilibrated, spin-orbit split levels of the (3)LF term. The (3)LF and (3)MLCT excited-state terms lie close in energy in the 4-CF(3)-Ph compound, resulting in an emission band shape that is temperature-dependent. At 77 K, the emission band is broad and structureless and is assigned to arise primarily from the (3)MLCT term. As the temperature is lowered toward 5 K, the (3)MLCT emission diminishes in intensity accompanied by the development of a vibrational structure that is characteristic of emission from the (3)LF term. These excited-state terms satisfy the requirements (different orbital origins, near-degeneracy) for separation by a Franck-Condon energy barrier, resulting in simultaneous emission from both terms between 5 and 77 K. 相似文献
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Potential Analysis - We prove weighted fractional Leibniz-type rules for Coifman–Meyer and biparameter Coifman–Meyer multiplier operators. Mapping properties of such operators in the... 相似文献
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Spectrophotometric methods were used to investigate the rate of the reaction of Br2 with HCOOH in aqueous, acidic media. The reaction products are Br? and CO2. The kinetics of this reaction are complicated by both the formation of Br3? as Br? is formed and the dissociation of HCOOH into HCOO? and H+. Previous work on this reaction was carried out at acidities lower than the highest used here and led to the conclusion that only HCOO? reacts with Br2. It is agreed that this is by far the principal reaction. However, at the highest acidity experiments, an added small component of reaction was found, and it is suggested that it results from the direct reaction of Br2 with HCOOH itself. On this assumption, values of the rate constants for both reactions are derived here. The rate constant for the reaction of HCOO? with Br2 agrees with values previously reported, within a factor of 2 on the low side. The reaction involving HCOOH is more than 2000 times slower than the reaction involving HCOO?, but it does contribute to the overall rate as [H+] approaches 1M. These derived rate constants are able to simulate quantitatively the authors' absorbance-versus-time data, demonstrating the validity of their data treatment methods, if not mechanistic assignments. Finally, activation parameters were determined for both rate constants. The values obtained are: ΔE?(HCOOH + Br2) = 13.3 ± 1.1 kcal/mol, ΔS? (HCOOH + Br2) = ?28 ± 3 cal/deg mol, ΔE? (HCOO? + Br2) = 13.1 ± 0.9 kcal/mol, and ΔS?(HCOO? + Br2) = ?12 ± 1 cal/deg mol. That the activation energies of the two reactions turn out to be essentially identical does not support the authors' suggestion that both HCOOH and HCOO? react with Br2. 相似文献