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81.
Tiago Buckup Timo Lebold Alexander Weigel Wendel Wohlleben Marcus Motzkus 《Journal of photochemistry and photobiology. A, Chemistry》2006,180(3):314-321
Biomolecules very often present complex energy deactivation networks with overlapping electronic absorption bands, making their study a difficult task. This can be especially true in transient absorption spectroscopy when signals from bleach, excited state absorption and stimulated emission contribute to the signal. However, quantum control spectroscopy can be used to discriminate specific electronic states of interest by applying specifically designed laser pulses. Recently, we have shown the control of energy flow in bacterial light-harvesting using shaped pump pulses in the visible and the selective population of pathways in carotenoids using an additional depletion pulse in the transient absorption technique. Here, we apply a closed-loop optimization approach to β-carotene using a spatial light modulator to decipher the energy flow network after a multiphoton excitation with a shaped ultrashort pulse in the near-IR. After excitation, two overlapping bands were detected and identified as the S1 state and the first triplet state T1. Using the transient absorption signal at a specific probe delay as feedback, the triplet signal could be optimized over the singlet contribution. 相似文献
82.
This paper presents a method of measuring a light field of a light source with high directional resolution using a mirrored
ball and a pinhole camera. The light field describes a spatial and directional distribution of radiances from the light source.
The directional distribution is expanded by a reflection on the mirrored ball, and the radiances are measured by a charge-coupled
device (CCD) camera with a pinhole lens. The light source is laterally moved by a robot arm to measure the directionally expanded
light field, and each pixel on a CCD can obtain the radiances from the light source through the pinhole lens with high directional
resolution. The light field is estimated from the pixel value and the position of each pixel using a ray tracing technique.
The light field of a krypton lamp was experimentally measured by the proposed method, and the accuracy of the measurement
was evaluated against the irradiances measured by a spectro-radiometer at sample points. 相似文献
83.
Boniface Nkemzi 《Mathematical Methods in the Applied Sciences》2006,29(9):1053-1080
This paper is concerned with the structure of the singular and regular parts of the solution of time‐harmonic Maxwell's equations in polygonal plane domains and their effective numerical treatment. The asymptotic behaviour of the solution near corner points of the domain is studied by means of discrete Fourier transformation and it is proved that the solution of the boundary value problem does not belong locally to H2 when the boundary of the domain has non‐acute angles. A splitting of the solution into a regular part belonging to the space H2, and an explicitly described singular part is presented. For the numerical treatment of the boundary value problem, we propose a finite element discretization which combines local mesh grading and the singular field methods and derive a priori error estimates that show optimal convergence as known for the classical finite element method for problems with regular solutions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
84.
超子中子星性质的温度效应 总被引:2,自引:0,他引:2
从相对论平均场理论出发,考虑核子、超子和介子的相互作用,研究了温度对中子星组成粒子、状态方程和中子星质量等的影响.发现温度越高,超子在中子星内部出现时的重子数密度越低.当密度较高时,中子星的核心区主要由超子组成,即中子星转变成以奇异粒子为主要成分的超子星,并且这种转变受到温度的影响,温度越高,转变密度越低.由于超子的出现,中子星核心高密度区域的状态方程,对于不同温度,差别不大,所以有限温度中子星的最大质量都在1.8M⊙附近.这与观测结果相符. 相似文献
85.
Ledzewicz U. Nowakowski A. Schättler H. 《Journal of Optimization Theory and Applications》2004,122(2):345-370
It is shown that, if a parametrized fämily of extremals F can be stratified in a way compatible with the flow map generated by F, then those trajectories of the family which realize the minimal values of the cost in F are indeed optimal in comparison with all trajectories which lie in the region R covered by the trajectories of F. It is not assumed that F is a field covering the state space injectively. As illustration, an optimal synthesis is constructed for a system where the flow of extremals exhibits a simple cusp singularity. 相似文献
86.
构造了第孙中禹种强度不等的非对称三态叠加多模叠加态光场|ψ1(ABC)〉q.利用多模压缩态理论研究了态|ψ1(ABC)〉q第一正交分量高次和压缩.结果发现:①当构成态|ψ1(ABC)〉q的三个多模相干态光场的强度不相等时,在一定条件下,态|ψ1(ABC)〉q的第一正交分量可出现任意幂次的高次和压缩.②当上述的三个多模相干态光场强度相等时,态|ψ1(ABC)〉q的第一正交分量的高次和压缩现象消失.在这种情况下,态|ψ1(ABC)〉q的第一正交分量恒处于NH最小测不准态. 相似文献
87.
Yasumitsu Matsuo Takehiko Ijichi Hironori Yamada Junko Hatori Seiichiro Ikehata 《Central European Journal of Physics》2004,2(2):357-366
We have fabricated a field effect transistor (FET) based on an organic ferroelectric insulator and molecular conductor, and
investigated the electrical properties and memory effects on the PEN-FET. We have observed a drastic change in the drain current
at around the coercive electric fieldE
c
of the organic ferroelectric insulator in not only a FET (PEN-FET) based on a pentacene (PEN) film but also a FET (IPEN-FET)
based on an iodine doped PEN film. The magnitude of the change of the drain current for the IPEN-FET is 200 times larger than
that for the PEN-FET. It is expected from these results that the PEN-FET (especially the IPEN-FET) is an improvement in such
devices, since it operates at a low gate electric field accompanied by the appearance of the spontaneous polarization in the
organic ferroelectric insulator. In addition, we have found that the drain current for the PEN-FET does not return to the
initial drain current ofE
G
=0 V/cm for more than one week, even if the gate electric field is changed to 0 V/cm from 500 V/cm(>E
c
). From these results, it is suggested that the PEN-FET becomes a memory device. 相似文献
88.
本文就欧氏空间和球面中紧致子流形的Yang-Mills场进行了讨论.得到了一类不稳定性结果. 相似文献
89.
We show that there is a threshold in energy for the onset of chaos in cosmology for the Universe described as a dynamical system derived from the Einstein equations of General Relativity (GR). In the case of the mixmaster model (homogeneous and anisotropic cosmology with a Bianchi IX metric), the chaos occurs precisely at the prescribed necessary value H
vac=0 of the GR for the energy of the Universe while the system is found to be regular for H<0 and chaotic for H>0 with respect to its pure vacuum part. In the case of generalized scalar tensor theories within the Bianchi IX model, we show using the ADM formalism and a conformal transformation that the energy of the dynamical system as compared to vacuum lies below the zero energy threshold. The system is thus not exhibiting chaos and the conclusion still holds in the presence of ordinary matter as well. The suppression of chaos occurs in a similar way for stiff matter alone. 相似文献
90.
Sergey Chervon 《General Relativity and Gravitation》2004,36(7):1547-1553
A new strategy of exact solutions construction in inflationary cosmology within the self-interacting scalar field theory is proposed. It is shown that inflationary models have no restrictions dictated by the slow-roll approximation on the self-interacting potential. The suggested approach makes it possible to compute precisely the e-folds numbers in inflationary scenarios. The scalar field with a logarithmic evolution in time is analyzed in details. Other possible types of scalar field evolution are discussed. 相似文献