共查询到19条相似文献,搜索用时 78 毫秒
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介绍甲烷喇曼激光器的自调Q现象,并给出自调Q甲烷喇曼激光器有关特性的实验结果。实验中获得了单脉冲能量为4.9mJ、脉宽为6ns的1.54μm激光输出。 相似文献
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研究可激发气体中振动模式能量转移速率和声弛豫过程形成的关系,将单一气体Tanczos弛豫方程理论[J.Chem.Phys.25,439(1956)]扩展应用于混合气体中振动模式的振动-振动(V-V)和振动-平动(V-T)能量转移速率的计算。在室温下CO2,CH4,CL2,N2和O2组成的多种混合气体中,振动模式能量转移速率的计算结果表明:对于多个振动模式所形成的声复合弛豫过程,各振动模式的声激发能可由V-V能量转移相互耦合后传递给具有最快V-T转移速率的最低振动频率振动模式,再通过该振动模式的V-T转移退激发形成主弛豫过程。这种选择最快转移路径的声激发量弛豫方式,造成了大多数可激发气体中声弛豫吸收谱的实测数据只存在一个吸收峰的现象。从而提供了一个可通过计算微观振动能量转移速率分析混合气体声弛豫过程形成机理的理论模型。 相似文献
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报道了采用单次脉冲非稳腔空间增强探测 相干反斯托克斯喇曼散射(USED CARS)技术诊断常压下固体燃剂瞬态燃烧场温度和氮气浓度。采用宽带USED CARS技术,在固体燃剂瞬态燃烧场获得了较高信噪比的单次激光脉冲氮气Q支CARS实验谱,用CARS理论计算软件拟合CARS实验谱,给出了固体燃剂瞬态燃烧场温度和氮气浓度在不同高度的分布,固体燃剂燃烧场温度约2 250K、氮气相对浓度16%~20%。 相似文献
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G. Guillon T. Stoecklin A. Voronin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):83-87
We compare the cross sections for the transitions changing the projection of
the total angular momentum of N2
+(2Σ) in collisions
with 3He and 4He at very low collision energy. The fundamental
states of the two nuclear spin isomers of N2
+ are considered as
well as the two fine structure levels of the first excited para level N=2.
It is shown that the two fundamental states of the two nuclear spin isomers
behave differently. For the fundamental para level N=0 of N2
+, the
projection changing cross section is always negligible compared to the
elastic one for both He isotopes. For the fundamental ortho level N=1 of
N2
+, the spin-rotation interaction couples the different spin
levels directly so the spin relaxation becomes a first order process. The
associated resonances increase the projection changing cross section which
remains smaller but becomes comparable with the elastic one. This is in
contrast with the excited rotational levels of N2
+, which for the
rotational deactivation and elastic channels are found to be equal around
the resonances for the collisions involving 3He. These two channels are
always larger than the projection changing one. We also find that, for
transitions involving the fundamental rotational state, the domain of
validity of the threshold laws discussed by Krems and Dalgarno [Phys. Rev. A 67, 050704 (2003)] for a potential decreasing faster than
1/r2 is shortened, due to the long range charge induced dipole potential.
This effect is illustrated for the collisions of 3He with the
fundamental para state of N2
+. 相似文献
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通过求解Lorentz简化的玻尔兹曼方程,得到射频放电CH4等离子体中电子的能量分布函数.求解过程中使用一个简化的射频电场模型代替泊松方程求解放电电场.共计包含6类环境气体及27种电子碰撞反应.通过EEDF对等离子体中的电子反应率系数、电子平均能量、电子的传输率系数等进行求解分析.结果表明,在等离子体鞘层区域电子能量具有Maxwell分布形式,在正柱区域具有Druyvesteyn分布形式.最高电子能量和最大反应率系数出现在鞘层区域.电子的迁移率系数和扩散率系数随射频周期的演化时空分布不均匀. 相似文献
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Vibrational relaxation dynamics in transient grating spectroscopy studied by rate equations based on time-dependent correlation function 下载免费PDF全文
A modified model, a set of rate equations based on time-dependent correlation function, is used to study vibrational relaxation dynamics in transient grating spectroscopy. The dephasing, the population dynamics, and the vibrational coherence concerning two vibrational states are observed respectively in organic dye IR780 perchlorate molecules doped polyvinyl alcohol matrix. The result shows that in addition to the information concerning system-environment interac- tion and vibrational coherence, the vibrational energy transfer can be described by this modified model. 相似文献
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The phonon-assisted process of energy transfer aiming at exploring the newly emerging frontier between biology and physics is an issue of central interest.This article shows the important role of the intramolecular vibrational modes for excitation energy transfer in the photosynthetic systems.Based on a dimer system consisting of a donor and an acceptor modeled by two two-level systems,in which one of them is coupled to a high-energy vibrational mode,we derive an effective Hamiltonian describing the vibration-assisted coherent energy transfer process in the polaron frame.The effective Hamiltonian reveals in the case that the vibrational mode dynamically matches the energy detuning between the donor and the acceptor,the original detuned energy transfer becomes resonant energy transfer.In addition,the population dynamics and coherence dynamics of the dimer system with and without vibration-assistance are investigated numerically.It is found that,the energy transfer efficiency and the transfer time depend heavily on the interaction strength of the donor and the high-energy vibrational mode,as well as the vibrational frequency.The numerical results also indicate that the initial state and dissipation rate of the vibrational mode have little influence on the dynamics of the dimer system.Results obtained in this article are not only helpful to understand the natural photosynthesis,but also offer an optimal design principle for artificial photosynthesis. 相似文献
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T. Stoecklin A. Voronin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):259-265
A quantum mechanical investigation of vibrational and rotational energy transfer in cold and ultra cold collisions of CH+ with 3He and 4He atoms is presented. Ab initio potential energy calculations are carried out at the BCCD(T) level and a global 3D potential
energy surface is obtained using the Reproducing Kernel Hilbert Space (RKHS) method. Close coupling scattering calculations
using this surface are performed at collision energy ranging from 10-6 to 2000 cm-1. In the very low collision energy
limit, the vibrational and rotational quenching cross sections of CH+ in collisions with He are found to be of the same order of magnitude. This unusual result is attributed to the large angular
anisotropy of the intermolecular potential and to the unusually small equilibrium value of the Jacobi R coordinate of the
He–CH+ complex. As for the He–N2
+ collision, we also find a strong isotope effect in the very low collision energy range which is analyzed in terms of scattering
length and the differences between these two collisions are also discussed. 相似文献
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The specific features of the triplet-triplet (T-T) transfer of electronic excitation energy in a gas phase upon nonequilibrium
vibrational excitation of the triplet molecules of a donor were studied for an anthraquinone-diacetyl donor-acceptor pair
using the time-resolved slow fluoresence of anthraquinone and sensitized phosphorescence of diacetyl. It is shown that in
the gas phase, which allows regular control of the number of collisions, competition between the processes of T-T transfer
and intermolecular vibrational relaxation is observed for nanosecond time resolution. The T-T transfer rate for the molecular
system investigated exceeded the rate of intermolecular vibrational relaxation kV in the triplet state T1 of the donor. The effectiveness of the T-T transfer of energy by vibrationally excited molecules turned out to be higher
than the effectiveness of transfer by thermalized ones, but even the highest of them was much less than unity. An increase
in the equilibrium temperature of vapors led to a decrease in the effectiveness of transfer for both vibrationally excited
and thermalized triplet molecules, thus indicating the importance of the collisional complex in the intermolecular process
studied.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 474–479, July–August, 2000. 相似文献
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The important role of high-energy intramolecular vibrational modes for excitation energy transfer in the detuned photosynthetic systems is studied. Based on a basic dimer model which consists of two two-level systems(pigments)coupled to high-energy vibrational modes, we find that the high-energy intramolecular vibrational modes can enhance the energy transfer with new coherent transfer channels being opened when the phonon energy matches the detuning between the two pigments. As a result, the energy can be effectively transferred into the acceptor. The effective Hamiltonian is obtained to reveal the strong coherent energy exchange among the donor, the acceptor, and the high-energy intramolecular.A semi-classical explanation of the phonon-assisted mechanism is also shown. 相似文献
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Photo-induced intramolecular electron transfer and intramolecular vibrational relaxation of rhodamine 6G in DMSO revealed by multiplex transient grating spectroscopy 下载免费PDF全文
Photo-induced intramolecular electron transfer (PIET) and intramolecular vibrational relaxation (IVR) dynamics of the excited state of rhodamine 6G (Rh6G+) in DMSO are investigated by multiplex transient grating. Two major compo- nents are resolved in the dynamics of Rh6G+. The first component, with a lifetime τTPIET = 140 fs-260 fs, is attributed to PIET from the phenyl ring to the xanthene plane. The IVR process occurring in the range ZIVR = 3.3 ps-5.2 ps is much slower than the first component. The PIET and IVR processes occurring in the excited state of Rh6G+ are quantitatively determined, and a better understanding of the relationship between these processes is obtained. 相似文献