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41.
Zgierski MZ Patchkovskii S Fujiwara T Lim EC 《The journal of physical chemistry. A》2005,109(42):9384-9387
The ultrafast radiationless decay of photoexcited uracil and cytosine has been investigated by ab initio quantum chemical methods based on CIS and CR-EOM-CCSD(T) electronic energy calculations at optimized CIS geometries. The calculated potential energy profiles indicate that the S(1) --> S(0) internal conversion of the pyrimidine bases occurs through a barrierless state switch from the initially excited (1)pipi state to the out-of-plane deformed excited state of biradical character, which intersects the ground state at a lower energy. This three-state nonradiative decay mechanism predicts that replacement of the C5 hydrogen by fluorine introduces an energy barrier for the initial state switch, whereas replacement of the C6 hydrogen by fluorine does not. These predictions are borne out by the very different fluorescence yields of 5-fluorinated bases relative to the corresponding 6-fluorinated bases. It is concluded from these results that the origin of the ultrafast radiationless decay is the same for the two pyrimidine bases. 相似文献
42.
D. V. Fedoseev N. G. Sanzharlinskii N. F. Kirova S. P. Vnukov 《Russian Chemical Bulletin》1978,27(11):2369-2371
Conclusions Equations were established that relate the growth rate of diamond crystals in the region of its thermodynamic stability to the synthesis time.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2647–2649, November, 1978. 相似文献
43.
44.
We base ourselves on the construction of the two-dimensional random interlacements (Comets et al., 2016) to define the one-dimensional version of the process. For this, we consider simple random walks conditioned on never hitting the origin. We compare this process to the conditional random walk on the ring graph. Our results are the convergence of the vacant set on the ring graph to the vacant set of one-dimensional random interlacements, a central limit theorem for the interlacements’ local time and the convergence in law of the local times of the conditional walk on the ring graph to the interlacements’ local times. 相似文献
45.
Diego F. de Bernardini Christophe Gallesco Serguei Popov 《Stochastic Processes and their Applications》2018,128(10):3221-3252
In this paper we consider the field of local times of a discrete-time Markov chain on a general state space, and obtain uniform (in time) upper bounds on the total variation distance between this field and the one of a sequence of i.i.d. random variables with law given by the invariant measure of that Markov chain. The proof of this result uses a refinement of the soft local time method of Popov and Teixeira (2015). 相似文献
46.
Nina Gantert Sebastian Müller Serguei Popov Marina Vachkovskaia 《Journal of Theoretical Probability》2010,23(4):1002-1014
We study survival of nearest-neighbor branching random walks in random environment (BRWRE) on ℤ. A priori there are three
different regimes of survival: global survival, local survival, and strong local survival. We show that local and strong local
survival regimes coincide for BRWRE and that they can be characterized with the spectral radius of the first moment matrix
of the process. These results are generalizations of the classification of BRWRE in recurrent and transient regimes. Our main
result is a characterization of global survival that is given in terms of Lyapunov exponents of an infinite product of i.i.d.
2×2 random matrices. 相似文献
47.
Tse JS Klug DD Patchkovskii S Ma Y Dewhurst JK 《The journal of physical chemistry. B》2006,110(8):3721-3726
The nature of chemical bonding of the stable phases of Si at high pressure was analyzed. The effect of pressure is to promote sp electrons into the d orbitals, thus increasing the metallic character and reducing the dimensionality of covalent bonding. Localized covalent bonds, however, persist up to approximately 40 GPa (Si-VI, Cmca) and help to stabilize directional framework structures. At high pressures, Si becomes a metal, and the usual dense packed structures prevail. The existence of conducting and localized electrons gives rise to a combination of "steep and flat bands" near the Fermi level in Si-V. This peculiar electron topology in conjunction with low-frequency vibrations contributes to the relatively high superconducting temperature in Si-V and VI. 相似文献
48.
We report controllable (slow or fast) propagation of low-intensity probe-light pulses through erbium-doped fiber periodically saturated by the synchronized master-pulse sequence. These two pulse sequences could have significantly different carrier wavelengths within the fundamental absorption spectrum 1470-1570 nm of Er(+3) ions. The effect of fractional delay or advancement grew with the fiber optical absorption at the probe wavelength and could be significantly stronger than that at the saturating wavelength. The probe-pulse advancement was observed in the case when the saturating and probe waves were modulated approximately in antiphase. The observed effects are explained in the framework of a simple model of a periodically saturated homogeneously broadened absorption line. 相似文献
49.
Letters in Mathematical Physics - I describe a combinatorial construction of the cohomology classes in compactified moduli spaces of curves $$\widehat{Z}_{I}\in H^{*}\left( \bar{\mathcal... 相似文献
50.
Journal of Experimental and Theoretical Physics - We present a general scheme to approach the space-time evolution of deformations, currents, and the electric field in charge density waves related... 相似文献