Electronic absorption, formula

The electronic absorption spectra of a series of complexes of formula Re(CO)3(L)(DBSQ)[DBSQ = 3,5-ditert-butyl-l,2-benzosemiquinone] show a single maximum in the visible spectrum. The absorption maxima for three of these complexes in benzene solution are shown below typical molar absorptivities are in the range of 5,000 to 6,000 L mol cm . ... 

Most of the qualitative relationships between color and structure of methine dyes based on the resonance theory were established independently during the 1940 s by Brooker and coworkers (16, 72-74) and by Kiprianov (75-78), and specific application to thiazolo dyes appeared later with the studies of Knott (79) and Rout (80-84). In this approach, the absorptions of dyes belonging to amidinium ionic system are conveyed by a group of contributing structures resulting from the different ways of localization of the 2n rr electrons on the 2n l atoms of the chromophoric cationic chain, rather than by a single formula ... 

The expression for the rate R (sec ) of photon absorption due to coupling V beriveen a molecule s electronic and nuclear charges and an electromagnetic field is given through first order in perturbation theory by the well known Wentzel Fermi golden rule formula (7,8) ... 

Peaks are analyzed separately by their retention times, absorption, and fluorescence properties. RCCs show absorbance maxima near A.500 and 316 nm. For FCCs, UV-Vis specna show two prominent bands near 361 and 320 mn and a luminescence maximum at 436 mn and NCCs show UV-Vis spectra with absorbance maxima near 320 and 210 nm. Nevertheless, as none of these approaches is suitable for elucidating structures, it is necessary to apply additional MS and NMR analyses to fully characterize snuctural features. Electron spray ionization (ESI) and high-resolution EAB mass spectroscopy have been applied to elucidate the molecular formulae of colorless compounds. ... 

The first direct characterization of the structure of a sterically hindered diarylgermy-lene in solution was claimed for compound 26 (Ar = Ar5 in formula 11), using EXAFS (extended X-ray absorption fine structure), UVV (7-max 420 nm) and H and 13C NMR114. The UVV spectra of diarylgermylenes (26), their dimerization products (27) and the complexes formed with compounds containingp-electrons (28) were studied in solution115,116. 

The situation becomes even worse when the Boltzmann formula is used to interpret the absorption of radiant energy by molecules. Electromagnetic radiation considered as a fluctuating electric field interacts with electrons in... 

In almost all applications, fluorescent pH indicators are employed in a pH range around the ground state pKa (even if the excited state pK is different). Therefore, the absorption (and excitation) spectrum depends on pH in the investigated range. These indicators can be divided into three classes (see formulae in Figure 10.2) on the basis of the elementary processes (photoinduced proton transfer or electron transfer) that are involved. 

Pseudopterosin X (1) was isolated as a yellow colored gum. The UV spectrum of 1 showed maximum absorption at 280 nm due to the presence of a highly substituted benzene chromophore [10], Its IR spectmm displayed intense absorption bands at 3,470 (OH), 2,904 (CH), 1,705 (C = O), 1,595 (C = C) and 1,100 (C-0) cm . The high-resolution electron-impact mass spectmm (HREIMS) of 1 showed M+ at m/z 474.2622, and this mass provided molecular formula indicating the presence of nine double bond equivalents in 1. The C-NMR chemical shift assignments of 1 are shown around stracture 1. On the basis of the detailed NMR studies and comparison with the reported pseudopterosins in the literature and L-xylose [3-5], stmcture 1 was proposed for this new natural product. 

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