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11.
Raman and FTIR spectroscopies of fluorescein in solutions 总被引:3,自引:0,他引:3
Wang L Roitberg A Meuse C Gaigalas AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(9):1781-1791
Raman and Fourier transform-infra red (FT-IR) spectroscopies of fluorescein in aqueous solutions have been investigated in the pH range from 9.1 to 5.4. At pH 9.1 fluorescein is in the dianion form. At pH 5.4, fluorescein is a mixture of monoanion (approximately 85%), dianion and neutral forms (together approximately 15%). The fluorescence quantum yield drops from 0.93 for the dianion form to 0.37 for the monoanion form. The Raman and FT-IR studies focused on the frequency range from 1000 to 1800 cm(-1) which contains the skeletal vibrational modes of the xanthene moiety of fluorescein. At pH 9.1, the spectroscopic feature of fluorescein dianion are consistent with a picture of an electron delocalized among the xanthene moiety and two identical oxygens attached to opposite ends of the xanthene moiety, forming a very symmetric structure. The characteristic of fluorescein dianion is the presence of the phenoxide-like stretch at 1310 cm(-1). At pH 5.4, fluorescein monoanion has lost the symmetric structure characteristic of the dianion. The spectra of the monoanion have distinctive contributions from the phenolic bend at 1184 cm(-1). The assignments of the vibrational bands shown in Raman and FT-IR spectra are given based on both literature and the ab initio calculations at the Hartree-Fock level with HF/6-31 + +G* basis set. Excellent correlation is found between the experimental and calculated spectra. 相似文献
12.
A. Audzijonis L. Žigas G. Gaigalas R. Sereika B. Žygaitienė 《Journal of Cluster Science》2010,21(4):577-589
The photoelectron emission spectra of BiSCl crystal and molecular clusters have been calculated by the Density Functional
Theory (DFT) method. Molecular clusters consists from 2 to 20 molecules in one double chain along z(c) axis. Total and partial density of states of BiSCl crystal and clusters have been weighted with atomic photoemission emission
cross-section. The molecular clusters have been investigated including all normal modes of vibration. Theoretical results
of BiSCl crystal and molecular clusters have been compared with experimental X-ray photoelectron emission spectra (XPS) of
BiSI crystal. 相似文献
13.
Motivated by a demand for explicit genus 1 Belyi maps from theoretical physics, we give an efficient method of explicitly computing genus one Belyi maps by (1) composing covering maps from elliptic curves to the Riemann sphere with simpler (univariate) genus zero Belyi maps, as well as by (2) composing further with isogenies between elliptic curves. The computed examples of genus 1 Belyi maps has doubly-periodic dessins d’enfant that are listed in the physics literature as so-called brane-tilings in the context of quiver gauge theories. 相似文献
14.
Raimundas Vidūnas 《Linear algebra and its applications》2007,422(1):39-57
Let V denote a vector space with finite positive dimension, and let (A, A∗) denote a Leonard pair on V. As is known, the linear transformations A, A∗ satisfy the Askey-Wilson relations
15.
Gediminas Gaigalas Zenonas Rudzikas Oliver Scharf 《Central European Journal of Physics》2004,2(4):720-736
The general tensorial form of the hyperfine interaction operator in the formalism of second quantization is presented. Both
diagonal and off-diagnonal matrix elements of the above-mentioned operator are found using an approach based on a combination
of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin)
and a generalised graphical technique. This methodology allows us to account for correlation effects efficiently and, therefore,
to study the hyperfine interactions in complex many-electron atoms, those with openf-shells included, in a practical manner. All this will lead us to design an efficient program for large scale calculations
of hyperfine structure and isotope shift. 相似文献
16.
Algirdas Audzijonis Gediminas Gaigalas Leonardas Žigas Audrius Pauliukas Raimundas Žaltauskas Aurimas Čerškus Jurgis Narusis 《Central European Journal of Physics》2005,3(3):382-394
This paper presents the theoretical investigation of energy levels of valence bands (VB) and core levels (CL) of the ferroelectric
SbSl single crystals in antiferroelectric and ferroelectric phases. Since the best approximation for the deep VB levels is
a calculation by the Hartree-Fock method, the molecular model of a SbSI crystal was used for calculations. This model of the
crystal was also used for calculations of the total density of states. It was found that the VB and CL of this ferroelectric
semiconductor are sensitive to the small lattice distortion at the phase transition, and that an average of the total density
of states, when all atoms participate in oscillations of all normal modes, are more similar to the experimental X-ray photoelectron
spectra (XPS). The experimental splitting of CL obtained by XPS was compared with the theoretically calculated one by two
different methods. The cluster model calculations showed that the splitting of the CL in SbSI might be caused by photoelectron
emission from the atoms, which have different valence state, at the surface. 相似文献
17.
18.
Raimundas Vidūnas 《Discrete Mathematics》2008,308(4):479-495
It is known that if (A,A*) is a Leonard pair, then the linear transformations A, A* satisfy the Askey-Wilson relations
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20.
The effect of agarose gel concentration and field strength on the electrophoretic trapping of open (relaxed) circular DNA was investigated using microscopic measurements of individual molecules stained with a fluorescent dye. Three open circles with sizes of 52.5, 115, and 220 kbp were trapped by the electric field (6 V/cm) and found to be predominately fixed and stretched at a single point in the gel. The length of the stretched circles did not significantly change with agarose concentration of the gels (mass fractions of 0.0025, 0.01, and 0.02). The relaxation kinetics of the trapped circles was also measured in the gels. The relaxation of the large open circles was found to be a slow process, taking several seconds. The velocity and average length of the 52.5 kbp open circles and 48.5 kbp linear DNA were measured during electrophoresis in the agarose gels. The velocity increased when the agarose concentrations were lowered, but the average length of the open-circle DNA (during electrophoresis) did not significantly change with agarose gel concentrations. The circles move through the gels by cycles of stretching and relaxation during electrophoresis. Linear dichroism was also used to investigate the trapping and alignment of the 52.5 kbp open circles. The results in this study provide information that can be used to improve electrophoretic separations of circular DNA, an important form of genetic material and commonly used to clone DNA. 相似文献