نتایج جستجو برای: spectra
تعداد نتایج: 108325 فیلتر نتایج به سال:
the synthesis of smcl3(thf)3 from smcl3.6h2o is described. the reaction of smcl3(thf)3 with nabh4 in dry thf gave white microcrystalline tris (tetrahydroborato) tris (tetrahydrofuran) samarium (iii), sm(bh4)3(thf)3. the vibrational and magnetic properties of sm(bh4)3(thf)3 have been studied.
Radiotherapy using linear accelerators is known as an effective modality for cancer treatment. The photons energy of treatment beams significantly affect the dose distribution. Therefore, it is important to accurately evaluate the photon energy spectra. In this study, MCNPX Monte Carlo code (version 2.6.0) was used to simulate an 18 MV photon beam of a Varian 2100C/D linear accelerator. By matc...
Cytochrome c', a c-type cytochrome with unique spectroscopic and magnetic properties, has been characterized in a variety of denitrifying and photosynthetic bacteria. Cytochrome c' has a role in defence and/or removal of NO but the mechanism of action is not clear. To examine the function of cytochrome c' from Neisseria meningitidis, the protein was purified after heterologous overexpression in...
The synthesis of the new diethyl ammonium salt of diethylammonium(E)-5-(1,5-bis(4-fluorophenyl)-3-oxopent-4-en-1-yl)-1,3-diethyl-4,6-dioxo-2-thioxohexaydropyrimidin-5-ide 3 via a regioselective Michael addition of N,N-diethylthiobarbituric acid 1 to dienone 2 is described. In 3, the carboanion of the thiobarbituric moiety is stabilized by the strong intramolecular electron delocalization with t...
Jahn-Teller (JT) distortions and charge localization in the benzene dimer cation are analyzed using the equation-of-motion coupled cluster with single and double substitutions for ionization potential (EOM-IP-CCSD) method. Ionization of the dimer changes the bonding from noncovalent to covalent and induces significant geometrical distortions, e.g., shorter interfragment distance and JT displace...
The influence of geometry variations and solvent environment of N-methylacetamide on its energies and absorption intensities was systematically analyzed with the aid of the time-dependent density functional theory (TD DFT). Selective and often complicated reactions of individual electronic levels on the perturbations were found important for the resultant spectral profile. For example, the n-pi...
We report gas-phase electronic spectra of formamide, N-methyformamide, acetamide, and N-methylacetamide at 300 K calculated using a combination of classical molecular dynamics and time-dependent density functional theory (TDDFT). In comparison to excitation energies computed using the global minima structures, the valence npi* and pi(nb)pi* states show a significant red-shift of 0.1-0.35 eV, wh...
The so-called Vegetation Red-Edge (VRE), a sharp increase in the reflectance around 700 nm, is a characteristic of vegetation spectra, and can therefore be used as a biomarker if it can be detected in an unresolved extrasolar Earth-like planet integrated reflectance spectrum. Here we investigate the potential for detection of vegetation spectra during the last Quaternary climatic extrema, the L...
We present photodissociation spectroscopy and computational analysis of three monocationic Cu-bipyridine complexes with one additional ligand of different interaction strength (N2, H2O and Cl) in the visible and UV. All three complexes show similar ππ* bands with origins slightly above 4 eV and vibrational band contours that are due to bipyridine ring deformation modes. Experiments at low tempe...
Electronic absorption spectra of chrysophanol (1,8-dihydroxy-3-methylanthracene-9,10-dione), physcion (1,8-dihydroxy-3-methoxy-6-methylanthracene-9,10-dione) and emodin (1,3,8trihydroxy-6-methylanthracene-9,10-dione) were investigated. Molecular geometries of the substituted anthraquinones in the ground state were optimized using semiempirical AM1 method without imposing any symmetry constrains...
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