Home OALib Journal OALib PrePrints Submit Ranking News My Lib FAQ About Us Follow Us+
 Title Keywords Abstract Author All
Search Results: 1 - 10 of 100 matches for " "
 Page 1 /100 Display every page 5 10 20 Item
 Physics , 2010, Abstract: Entanglement control of qubits in a photoisomerizing molecule is studied in the context of an NMR quantum computer by taking azobenzene as an example. Azobenzene has two different isomers, {\it{}trans}-azobenzene (TAB) and {\it{}cis}-azobenzene (CAB), which can be interconverted by photoisomerization. Changing molecular structure leads to change in the spin-spin coupling constant, and hence leads to change in entangling operation time. We first obtain stable structures of TAB and CAB by {\it ab initio} calculation. Then, we calculate the NMR spectra of these isomers and verify that they reproduce the chemical shift obtained experimentally with a good precision. Our result indicates that the coupling strength between a $^{15}$N and a $^{13}$C nuclei in the molecule changes by a large amount under photoisomerization.
 Latvian Journal of Physics and Technical Sciences , 2010, DOI: 10.2478/v10047-010-0009-y Abstract: One of the most important properties of the molecular switches is turning of a molecule by external action, e.g. by irradiation with light of definite wavelength. The molecules of promise for the molecular switches are those with azobenzene moiety. When azobenzene is irradiated with light of definite wavelength, it is possible to observe the process of trans/cis isomerisation. In this work, the influence of photoisomerisation processes on the changes in the surface potential of a novel azobenzene compound is investigated. We have studied the surface potential of a PMMA polymer film with polar azobenzene derivative of different concentrations. To orient azobenzene molecules in the film the corona poling method was used, and for studying the surface potential variations - the Kelvin probe method. The photoreaction time constant of the fast response (several seconds) was found to be almost independent of the molecular concentration in the polymer film and of the absorbed light intensity in the bulk of a sample. In contrast, the amplitude of photoinduced changes in the surface potential depends both on the concentration of azobenzene molecules and on the absorbed light intensity in bulk of the host-guest polymer film.
 中国物理 B , 2009, Abstract: The modulational instability of two incoherently coupled beams in azobenzene-containing polymer with photoisomerization nonlinearity is investigated analytically and numerically. Our results show that as a precursor to spatial optical soliton formation, modulational instability can be adjusted and controlled by the wavelength combinations of the signal and background beams. We also discuss the dependences of strength of modulational instability on intensities of two signal beams and background beam. These findings make it possible to predict the formation of incoherently coupled soliton pairs in azobenzene-containing polymer.
 物理学报 , 2004, Abstract: Z_scan experiments are performed on the azobenzene polymer (DR_13_PMMA) films with He_Ne laser. It is found that the relation between the change of refractive index of the sample and the light intensity behaves like a saturable effect, whose relative parameters are alterable with light intensity. It is also found that the change of refractive index induced by linearly polarized light is distinctly greater than that induced by circularly polarized light. The phenomena are explained by using the theory based on the effect of angular hole burning of photoisomerization.
 Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0554-z Abstract: We prepared the azobenzene PNA unit and synthesized various PNAs containing an azobenzene unit by a typical tBoc method. Both the azobenzene PNA unit and PNA containing an azobenzene unit (N-PNA) showed reversible photoisomerization with UV and visible light irradiation. The hybridization of N-PNA with complementary DNA resulted in a considerable decrease of the photoisomerization rate constant of the azobenzene.
 Physics , 2006, Abstract: We investigate photoisomerization (PI), the shape change of a molecule upon photoabsorption, in a dissipative environment using a simple spin-boson model. We identify two classes of environment depending on whether it "entangles" with the molecule. In the absence of entanglement, the environment merely causes a blue shift of the required photon frequency and reduces the quantum efficiency of PI. With entanglement the molecule can undergo a quantum phase transition between a state that photoisomerizes to a state that does not.
 Soft (Soft) , 2013, DOI: 10.4236/soft.2013.22003 Abstract: Study of interfacial processes between incorporated biomolecules and hydrogel matrix is of primary importance for the application of synthetic hydrogels as biomaterials, sensors, etc. Their hydrophilic nature, however, hampers fat-soluble biomolecule incorporation. We synthesized N-isopropylacrylamide (NIPAAm)- and Acrylamide (AA)-based hydrogels with hydrophilic-lipophilic balance that under specific conditions permit homogeneous incorporation of provitamins D3(7-dehydrocholesterol) and D2(ergosterol) dissolved in ethanol. Similarity of provitamins D photoisomerization in such hydrogel matrices with the photoreaction in ethanol shows great potential of the novel material for personal dosimetry of biologically active ‘antirachitic’ UV radiation.
 Chinese Science Bulletin , 2003, DOI: 10.1007/BF03183291 Abstract: The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.
 科学通报(英文版) , 2003, Abstract: The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.
 Physics , 2005, DOI: 10.1016/j.cplett.2005.05.025 Abstract: In this letter we propose a model which explains ultrafast and efficient photoisomerization reactions as driven by transitions between quasistationary states of one dimensional (1D) double well potential of an excited electronic state. This adiabatic potential is formed as a result of doubly crossing of a decay diabatic potential of the ground electronic state and a bound diabatic potential of the excited state. We calculate the eigenstates and eigenfunctions using the semiclassical connection matrices at the turning and crossing points and the shift matrices between these points. The transitions between the localized in the wells below the adiabatic barrier states are realized by the tunneling and by the double non-adiabatic transitions via the crossing points processes. Surprisingly the behavior with the maximum transition rate keeps going even for the states relatively far above the barrier (2 -4 times the barrier height). Even though a specific toy model is investigated here, when properly interpreted it yields quite reasonable values for a variety of measured quantities, such as a reaction quantum yield, and conversion time.
 Page 1 /100 Display every page 5 10 20 Item