Triplet-triplet transfer of electronic energy upon nonequilibrium vibrational excitation of triplet molecules

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 k_V 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.     

Ultrafine particle formation by resonant laser excitation of potassium molecules

In a heat pipe oven containing potassium and a noble gas we have observed a large production of metallic potassium particles upon resonant laser excitation of the K₂ molecules. This is a new method for particle production, based on the strong local heating of the vapor due to the high absorption rate of the laser light. As a consequence of the disequilibrium caused at the gas/vapour boundary by this heating, a supersaturated region is created where the vapor condenses and produces ultrafine particles.     

Auger spectra from resonant transfer excitation of O VI

Auger spectra observed in the resonant transfer excitation of O VI by He targets are analyzed in terms of the e+O⁵⁺ resonant excitation cross section. Peak ratio for the ³D and ¹D states of the intermediate state configuration (1s2s2p²) is found to be 3 : 1, in rough agreement with the experimental data. In addition, Auger decay of resonance states generated by collisional excitation of O VI (1s2s², 1s2s2p, 1s2p²) is examined.     

Endoergic and resonant charge transfer excitation in He-Cu discharge

The intensity of Cu-II lines with upper level energies near and above those of the He ion was measured as a function of He pressure in a Cu hollow cathode tube. In this tube at low pressures the negative glow could expand above the cathode. The maximum intensity of the Cu-II 493.1 nm line was found in the low voltage, high pressure hollow cathode discharge region in accordance with a resonant charge transfer excitation process. Enhancement of the intensity of the Cu-II 436.5 nm and 417.9 nm lines was observed in the cathode glow at low pressures. Excitation of these lines is attributed to endoergic charge transfer collisions between He ions accelerated by the 2 kV tube voltage and ground state Cu atoms. The cross-section for this reaction exciting the 436.5 nm line was estimated to be of the order of 10^–17 cm².     

Generation of nonclassical light upon resonant excitation of a semiconductor microcavity

Strong correlations in the fluctuations of the intensity of emission from a semiconductor microcavity under resonant laser excitation are observed. The intensity correlation function exhibits an unusual oscillatory behavior with an unexpectedly long oscillation period and decay time. The visibility of the correlation function reaches 0.81. Long oscillation times are attributed to the Rabi frequency characterizing weak coupling between the electromagnetic field of the semiconductor microcavity mode and long-lived exciton states localized by the random potential of the quantum well. For a laser excitation power density of 400 W/cm², the power density of the radiation emitted by the microcavity is 12 W/cm², which corresponds to the total flux of nonclassical light of 1.5 × 10¹⁵ photons/s from an excited spot 50 μm in diameter. Thus, a microcavity can serve as a bright emitter of nonclassical light.     

近共振电子态和转动能量传递

为了进一步研究在近共振电子态和非共振电子态转动能量传递的跃迁几率,以一阶含时波恩近似、各向异性Lennard-Jones相互作用势和直线轨迹近似为基础,我们建立了 的碰撞诱导的电子态和转动态的能量传递模型,通过此模型我们得到了实验温度、转动量子数和折合质量对能量传递的影响。     

Dielectronic recombination and resonant transfer excitation processes for helium-like krypton

The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) resonances.Then,the resonant transfer excitation(RTE) processes of Kr 34+ colliding with H,He,H 2,and CH x(x = 0-4) targets are investigated under the impulse approximation.The needed Compton profiles of targets are obtained from the Hartree-Fock wave functions.The RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the target.For H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ’ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H 2.For CH x(x = 0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the hydrogen.However,further comparison of the individual orbital contributions of C(2p,2s,1s) and CH 4(1t 2,2a 1,1a 1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.     

Phonon-assisted electronic excitation transfer near distortive phase transitions

An anomalous temperature dependence of the phonon-assisted electronic excitation transfer rate is to be expected near a distortive phase transition, when the energy mismatch between donor and acceptor energy levels is close to that of a soft optical mode, or an order-parameter-sensitive hard mode. In the case of electron coupling to soft acoustical modes, it is shown that the Debye model used in current theories breaks down near T_c.     

Modulation of the proton transfer rate by excitation photons

The effect of the exciting photon energy on the excited state proton transfer in a dye with dual fluorescence—FET (4′-diethylamino)-3-hydroxyflavone)—is studied. The steady-state fluorescence spectra are studied upon selective excitation by photons with different energies in the region of the main absorption band, as well as at its long-wavelength wing, in the temperature range of 2–30°C. It is found that, at all temperatures, the ratio of the integral emission of the normal and tautomeric forms, which are observed at 480 and 570 nm, respectively, depends on the excitation wavelength; namely, this ratio noticeably decreases with increasing excitation wavelength in the region of the main absorption band and its long-wavelength wing at 390–440 nm, and the rate of this decrease depends on temperature. In the same region, the long-wavelength excitation effect, which is atypical for inviscid solvents at room temperature, is observed; i.e., a short-wavelength emission band is bathochromically shifted by 6–15 nm depending on temperature. This spectral shift is directly related to the inhomogeneous broadening of the electronic spectra of the normal FET form, which is very large due to a considerable (>10 D) difference in the dye dipole moments. Most probably, the excitation creates the possibility of emission from nonrelaxed nonequilibrium orientational sublevels because their lifetime becomes shorter due to the proton transfer reaction, the rate of which in acetonitrile is comparable with the rate of intermolecular orientational relaxation. It is proposed to explain these dependences using energy diagram taking into account the dependence of the free energy on the orientational polarization of the solvent.     

Migration transfer of electronic excitation energy in activated solids

An analytic expression for the kinetics of quenching of donor luminescence in the presence of acceptors with allowance for migration of energy over the donor subsystem is derived. An extended criterion for the applicability of the hopping migration model is obtained.     

On the origin of nonclassical light generation upon resonant excitation of a GaAs semiconductor microcavity

It was shown in JETP Lett. 102, 508 (2015) that the intensity correlation function of the emission from a high-quality-factor semiconductor microcavity under resonant optical pumping exhibits an oscillatory behavior with an unexpectedly long oscillation period and a long decay time, which fall in the nanosecond range. A further investigation demonstrates that the origin of these oscillations is not related to the weak Rabi interaction between long-lived localized exciton states in the quantum well and the electromagnetic field of the microcavity mode. It proves that the semiconductor microcavity plays a secondary role in the observation of nonclassical light: it provides the spectral selection of the modes of the pump laser. We believe that intrinsic instabilities lead to the chaotic excitation of spiking in the laser modes under a constant operating current.     

Direct observation of optical excitation transfer based on resonant optical near-field interaction

This article reports the direct observation of long-distance optical excitation transfer based on resonant optical near-field interactions in randomly distributed quantum dots (QDs). We fabricated optical excitation transfer paths based on randomly distributed QDs by using CdSe/ZnS core?Cshell QDs and succeeded for the first time in obtaining output signals resulting from a unidirectional optical excitation transfer length of 2.4???m. Furthermore, we demonstrate that the optical excitation transfer occurs via the resonant excited levels of the QDs with a comparative experiment using non-resonant QDs. This excitation-transfer mechanism allows for intersecting, non-interacting nano-optical wires.     

锁模激光相干激发原子的超窄共振效应

本文提出一种相干激发理论模型,解释了文献[1～3]用锁模激光脉冲序列激发原子产生超窄共振效应的实质.推导了原子密度算符ρA(t)的表示式和光谱信号表示式,给出了有关曲线.而且预言了越窄共振效应的新结果.这一理论模型可推广应用于多光子过程.     

地球的扁率对卫星运动的影响

指导出地球引力场的势能,分析了卫星的椭圆轨道旋进的现象。     

Mechanisms of femtosecond energy transfer upon strong excitation in crystals

It is shown that the fast temperature-independent shift of the long-wavelength edge of fundamental absorption observed upon electron bombardment of alkali halide, alkaline-earth, and oxygen-containing crystals is caused by the impact mechanism. In the course of the impact shift of lattice ions, short-lived perturbation (mainly, of their valence shells) occurs. The perturbation fields in the vicinity of impact-shifted anions act for no more than 100 fs. As a result, the distribution of the density of states in the valence band of a crystal is distorted, and the long-wavelength shift of the fundamental-absorption edge may increase for less than 100 fs.     

Non-radiative transfer of electronic excitation energy in multi-component luminescent systems

Based on the theory of the influence of concentration on the luminescent properties of isotropic rigid solutions worked out for a two-component system [1], a generalization has been made for multi-component systems. It is shown that the derived expressions for quantum yields in multi-component systems describe satisfactorily the non-radiative excitation energy transfer in a three-component system.     

近共振电子态和转动能量传递AB(~1∑,J) +C(~sl_j)→AB(~1∑,J′) +C(~sl_(j′))(英文)

1995年沙等在静态池实验中观测到了碰撞诱导转动传能中的量子干涉效应,并且测量到了决定跃迁截面幅值的积分干涉角(J .Chem.Phys.,1995,102 ,2772).同时,孙等在理论上计算了CO A1Π(v=0)~e3∑-(v=1)与He,Ne以及其它碰撞伴的碰撞体系的积分干涉角,建立了相应的理论模型.然而,以前的研究都局限在碰撞伴通常被认为是没有结构的粒子,但是在碰撞过程中相互碰撞的两个粒子都有内部角动量,自旋-轨道相互作用又对反应速率起着非常重要的影响,同时也能够影响反应势垒的高度,因此这种近似忽略了碰撞伴原子对整个碰撞体系得影响.基于这种考虑,在这篇文章中我们从理论上研究AB(~1∑,J) C(~sl_j)→AB(~1∑,J′) C(~sl_(j′))的碰撞诱导的电子态和转动态的能量传递,应用一级含时波恩近似、各向异性L-J相互作用势和直线轨迹近似,建立了理论模型.并讨论和比较了在近共振电子态和非共振电子态两种情况下的振动传能的跃迁几率.     

Cavityless optical bistability in a thin semiconductor film upon the resonant excitation of excitons and biexcitons

The bistable properties of a thin semiconductor film under conditions of resonant excitation of coherent excitons and biexcitons by photons in one or two different pulses are studied theoretically. Fiz. Tverd. Tela (St. Petersburg) 40, 932–933 (May 1998)