30 research outputs found
Elimination mechanisms of Br(2)(+) and Br(+) in photodissociation of 1,1-and 1,2-dibromoethylenes using velocity imaging technique
No full textPhotodissociation of cis-, trans-, and 1,1-Dichloroethylene in the Ultraviolet Range: Characterization of Cl((2)P(J)) Elimination
No full textUltrafast Excited-State Dynamics of 6Azauracil Studied by Femtosecond Transient Absorption Spectroscopy
No full textUltrafast Excited-State Dynamics of 6‑Azauracil Studied by Femtosecond Transient Absorption Spectroscopy
No full textThe excited-state dynamics of 6-azauracil
in different solvents
have been studied using femtosecond transient absorption spectroscopy.
The molecule is populated to the S<sub>2</sub> state with a pump pulse
at 264 nm. Broad-band white light continuum which covers from 320
to 600 nm is used as the probe. With a global fitting analysis of
the measured transient spectra, three decay time constants, i.e.,
<0.3, 5.2 ± 0.1, and >1000 ps, are directly obtained in
the
solvent of acetonitrile. These newly observed lifetime constants are
important in clarifying its decay dynamics as well as in providing
a criterion for the ultrafast dynamics simulations in 6-azauracil
using quantum chemical theories. In combination with previous theoretical
works, the main decay channel is proposed: the initially populated
S<sub>2</sub> decays to S<sub>1</sub> through internal conversion
in <0.3 ps, followed by an intersystem crossing from S<sub>1</sub> to T<sub>1</sub> in 5.2 ± 0.1 ps. The >1000 ps component
is
due to the decay of the T<sub>1</sub> state. A comparison of the excited-state
dynamics in different solvents reveals that the decay from S<sub>1</sub> to T<sub>1</sub> shows a clear dependence on the polarity of the
solvents. With higher polarity, the S<sub>1</sub> excited state decays
faster. This observation is in line with the prediction by Etinski
et al. [Phys. Chem. Chem.
Phys. 2010, 12, 15665−15671], where a blue-shift of the
T<sub>1</sub> state potential energy surface leading to an increase
of the intersystem crossing rate was proposed. With the new information
obtained in the present measurement, a clearer picture of the decay
dynamics of 6-azauracil on the S<sub>2</sub> excited state is provided
Photodissociation Dynamics of Allyl Chloride at 200 and 266 nm Studied by Time-Resolved Mass Spectrometry and Photoelectron Imaging
No full text
Tissue-like P systems with evolutional symport/antiport rules
No full textTissue P systems with symport/antiport rules are a class of distributed parallel computing models inspired by the cell intercommunication in tissues, where objects are never modified in the process of communication, just changing their place within the system. In this work, a variant of tissue P systems, called tissue P systems with evolutional symport/antiport rules is introduced, where objects are moved from one region to another region and may be evolved during this process. The computational power of such P systems is studied. Specifically, it is proved that such P systems with one cell and using evolutional symport rules of length at most 3 or using evolutional antiport rules of length at most 4 are Turing universal (only the family of all finite sets of positive integers can be generated by such P systems if standard symport/antiport rules are used). Moreover, cell division rules are considered in tissue P systems with evolutional symport/antiport rules, and a limit on the efficiency of such P systems is provided with evolutional communication rules of length at most 2. The computational efficiency of this kind of models is shown when using evolutional communication rules of length at most 4. (C) 2016 Elsevier Inc. All rights reserved.National Natural Science Foundation of China [61033003, 61272161, 61370099, 61320106005, 61472154, 61602192]; Ph.D. Programs Foundation of Ministry of Education of China [20120142130008]; Innovation Scientists and Technicians Troop Construction Projects of Henan Province [154200510012]SCI(E)ARTICLE177-19337
Aptamer-Binding Directed DNA Origami Pattern for Logic Gates
No full textIn this study, an aptamer-substrate strategy is introduced to control programmable DNA origami pattern. Combined with DNA aptamer-substrate binding and DNAzyme-cutting, small DNA tiles were specifically controlled to fill into the predesigned DNA origami frame. Here, a set of DNA logic gates (OR, YES, and AND) are performed in response to the stimuli of adenosine triphosphate (ATP) and cocaine. The experimental results are confirmed by AFM imaging and time dependent fluorescence changes, demonstrating that the geometric patterns are regulated in a controllable and programmable manner. Our approach provides a new platform for engineering programmable origami nanopatterns and constructing complex DNA nanodevices.National Natural Science Foundation of China [61370099, 61272161, 61425002, 61472333, 61572046, 61320106005]SCI(E)[email protected]; [email protected]
Laser intensity determination using nonadiabatic tunneling ionization of atoms in close-to-circularly polarized laser fields
No full textWe conceive an improved procedure to determine the laser intensity with the momentum distributions from nonadiabatic tunneling ionization of atoms in the close-to-circularly polarized laser fields. The measurements for several noble gas atoms are in accordance with the semiclassical calculations, where the nonadiabatic effect and the influence of Coulomb potential are included. Furthermore, the high-order above-threshold ionization spectrum in linearly polarized laser fields for Ar is measured and compared with the numerical calculation of the time-dependent Schrodinger equation in the single-active-electron approximation to test the accuracy of the calibrated laser intensity. (C) 2016 Optical Society of AmericaNational Basic Research Program of China [2013CB922201]; National Natural Science Foundation of China [11274050, 11204356, 11334009, 11374329, 11425414, 11474321]; Youth Innovation Promotion Association of CAS [2011242]SCI(E)[email protected]; [email protected]
