Observation of Excitonic n-Strings In A Quasi-one-Deviensional Charge-Transfer Crystal

1993 ◽  
Vol 328 ◽  
Author(s):  
N. Peyghambarian ◽  
K. Meissner ◽  
B. Fluegel ◽  
S. Mazumdar ◽  
F. Guo ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Bound States ◽  
Theoretical Calculations ◽  
Exchange Interactions ◽  
Bound State ◽  
Collective Excitations ◽  
One Dimension ◽  
Coulomb Interactions ◽  
Light Pulses ◽  
New Type

ABSTRACTCollective excitations, such as plasmons, rotons, electron-hole liquid, and excitonic Molecules, have been extensively studied in condensed Matter.1 Wannier excitons in inorganic semiconductors are bound by the exchange interactions between two electrons of the exciton, and the bound state of More than two excitons is not possible. We demonstrate here a new type of collective excitations,2 bound states of Multiple charge-transfer (CT) excitons. Coulomb interactions in one dimension are shown to bind a train of several (More than two) CT excitons. Experimental evidence for these new type of elementary excitations is reported in a quasi-one-dimensional CT crystal of anthracene PMDA. High density excitation by femtosecond light pulses generates Multi-exciton chains, which we refer to as excitonic n-strings with n = 1, 2, 3, etc., along the stack axis of the crystal. Both the n = 2 excitonic string (biexciton) and the n = 3 string (tri-exciton) are observed. This report provides evidence for an n > 2 exciton chain in this system.2 The stability of the n-string exciton is supported by our theoretical calculations based on the extended Hubbard Hamiltonian in one dimension.

scholarly journals (1+1)-Dirac bound states in one dimension, with position-dependent Fermi velocity and mass

Open Physics ◽  
2013 ◽  
Vol 11 (4) ◽  
Author(s):  
Omar Mustafa
Keyword(s):  
Harmonic Oscillator ◽  
Bound States ◽  
Bound State ◽  
One Dimension ◽  
Fermi Velocity ◽  
Dirac Particles ◽  
The Continuum ◽  
Oscillator Models

AbstractWe extend Panella and Roy’s [17] work for massless Dirac particles with position-dependent (PD) velocity. We consider Dirac particles where the mass and velocity are both position-dependent. Bound states in the continuum (BIC)-like and discrete bound state solutions are reported. It is observed that BIC-like solutions are not only feasible for the ultra-relativistic (massless) Dirac particles but also for Dirac particles with PDmass and PD-velocity that satisfy the condition m(x) v F2 (x) = A, where A ≥ 0 is constant. Dirac Pöschl-Teller and harmonic oscillator models are also reported.

Effect of Biquadratic Exchange Upon Ferromagnetic Two-Magnon Bound States. II. Anisotropic Exchange

1974 ◽  
Vol 52 (1) ◽  
pp. 33-39 ◽  
Author(s):  
D. A. Pink ◽  
R. Ballard
Keyword(s):  
Bound States ◽  
Exchange Interactions ◽  
Bound State ◽  
Exchange Term ◽  
Zero Temperature ◽  
Biquadratic Exchange ◽  
Anisotropic Exchange ◽  
Bound State Spectrum ◽  
Mode Pair ◽  
Isotropic Exchange

We have investigated the two-magnon bound state spectrum of a ferromagnetically ordered system for which the Hamiltonian contains an anisotropic bilinear exchange term, an anisotropic biquadratic exchange term, and a single-ion anisotropy term. The bound states, labelled by a wave vector q which we have taken to be in the [111] direction, were calculated by using zero-temperature Green functions. The principal results are: (i) the existence of single-ion bound states in the absence of single-ion anisotropy and conversely, their absence in the presence of such anisotropy, in contrast to the case in which the exchange interactions are isotropic; (ii) the appearance of an S mode for values of q, [Formula: see text]; (iii) the ordering of bound states for isotropic exchange interactions wherein the S0 mode lies below the S1-mode, D-mode pair and where the S1 mode lies below (above) the D mode if they lie below (above) the band, no longer holds.

scholarly journals On coupling constant thresholds in one dimension

2021 ◽  
Vol 13 (1) ◽  
pp. 22-38
Author(s):  
Yu.D. Golovaty
Keyword(s):  
Bound States ◽  
Bound State ◽  
One Dimension ◽  
Positive Sequence ◽  
Asymptotic Formulas ◽  
Coupling Constant ◽  
First Order ◽  
Negative Eigenvalues ◽  
Bounded Functions ◽  
Limiting Behaviour

The threshold behaviour of negative eigenvalues for Schr\"{o}dinger operators of the type \[ H_\lambda=-\frac{d^2}{dx^2}+U+ \lambda\alpha_\lambda V(\alpha_\lambda \cdot) \] is considered. The potentials $U$ and $V$ are real-valued bounded functions of compact support, $\lambda$ is a positive parameter, and positive sequence $\alpha_\lambda$ has a finite or infinite limit as $\lambda\to 0$. Under certain conditions on the potentials there exists a bound state of $H_\lambda$ which is absorbed at the bottom of the continuous spectrum. For several cases of the limiting behaviour of sequence $\alpha_\lambda$, asymptotic formulas for the bound states are proved and the first order terms are computed explicitly.

scholarly journals On the Two-Magnon Bound States for the Quantum Heisenberg Chain with Variable Range Exchange

1997 ◽  
Vol 11 (11) ◽  
pp. 453-459 ◽  
Author(s):  
J. Dittrich ◽  
V. I. Inozemtsev
Keyword(s):  
Wave Function ◽  
Finite Difference ◽  
Bound States ◽  
Nearest Neighbor ◽  
Bound State ◽  
Spin Interaction ◽  
Heisenberg Chain ◽  
Variable Range ◽  
New Type

The spectrum of finite-difference two-magnon operator is investigated for quantum S=1/2 chain with variable range exchange of the form h(j-k)∝ sinh -2a(j-k). It is found that usual bound state appears for some values of the total pseudomomentum of two magnons as for the Heisenberg chain with nearest-neighbor spin interaction. Besides this state, a new type of bound state with oscillating wave function appears at larger values of the total pseudomomentum.

On the number of bound states of semirelativistic Hamiltonian with Dirac delta potentials in one dimension

2018 ◽  
Vol 96 (11) ◽  
pp. 1235-1241
Author(s):  
Fatih Erman
Keyword(s):  
Bound States ◽  
Bound State ◽  
One Dimension ◽  
Sufficient Condition ◽  
Explicit Criterion ◽  
State Problem ◽  
Dirac Delta ◽  
Bound State Problem

We study the bound state problem for semirelativistic N attractive Dirac δ-potentials in one dimension. We give a sufficient condition for the Hamiltonian to have N bound states and give an explicit criterion for it.

scholarly journals Coexistence of a new type of bound state in the continuum and a lasing threshold mode induced by PT symmetry

2020 ◽  
Vol 6 (34) ◽  
pp. eabc1160
Author(s):  
Qianju Song ◽  
Jiashun Hu ◽  
Shiwei Dai ◽  
Chunxiong Zheng ◽  
Dezhuan Han ◽  
...  
Keyword(s):  
Bound States ◽  
External Source ◽  
Bound State ◽  
Pt Symmetry ◽  
Lasing Threshold ◽  
Symmetric Perturbation ◽  
New Type ◽  
The Rich ◽  
Symmetric Systems ◽  
The Continuum

Some photonic systems support bound states in the continuum (BICs) that have infinite lifetimes, although their frequencies and momenta are matched to vacuum modes. Using a prototypical system that can be treated analytically, we show that each of these BICs always splits into a pair of new type BIC and lasing threshold mode when a parity-time (PT)–symmetric perturbation is introduced. The radiation loss at the lasing threshold is exactly balanced by the net gain of the particles. These PT symmetry-induced BICs are different from ordinary BICs, as they can be excited by an external source but do not radiate, and they carry a different quality factor divergence rate from that of the ordinary BICs. While most of the attention of PT-symmetric systems is captured by the coalescence of modes at exceptional points, the splitting of ordinary BICs is a new phenomenon that illustrates the rich physics embedded in PT-symmetric systems.

Theoretical and experimental research on slip and uplift of the timber-concrete composite beam

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 7079-7099
Author(s):  
Jianying Chen ◽  
Guojing He ◽  
Xiaodong (Alice) Wang ◽  
Jiejun Wang ◽  
Jin Yi ◽  
...  
Keyword(s):  
Differential Equations ◽  
Deformation Theory ◽  
Concrete Slab ◽  
Theoretical Calculations ◽  
Structural Element ◽  
Structural Efficiency ◽  
Theoretical Investigations ◽  
New Type ◽  
Interlayer Slip ◽  
Good Agreement

Timber-concrete composite beams are a new type of structural element that is environmentally friendly. The structural efficiency of this kind of beam highly depends on the stiffness of the interlayer connection. The structural efficiency of the composite was evaluated by experimental and theoretical investigations performed on the relative horizontal slip and vertical uplift along the interlayer between composite’s timber and concrete slab. Differential equations were established based on a theoretical analysis of combination effects of interlayer slip and vertical uplift, by using deformation theory of elastics. Subsequently, the differential equations were solved and the magnitude of uplift force at the interlayer was obtained. It was concluded that the theoretical calculations were in good agreement with the results of experimentation.

scholarly journals Anion-enhanced excited state charge separation in a spiro-locked N-heterocycle-fused push-pull zinc porphyrin

2021 ◽  
Author(s):  
Mandeep K. Chahal ◽  
Anuradha Liyanage ◽  
Ajyal Z. Alsaleh ◽  
Paul A. Karr ◽  
Jonathan P. Hill ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Charge Separation ◽  
Charge Transfer Complex ◽  
Zinc Porphyrin ◽  
New Type ◽  
State Charge

A new type of push–pull charge transfer complex, viz., a spiro-locked N-heterocycle-fused zinc porphyrin, ZnP-SQ, is shown to undergo excited state charge separation, which is enhanced by axial F− binding to the Zn center.

Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized Metalloid Gold Nanoclusters from Ehrenfest dynamics.

2021 ◽  
Author(s):  
Adrian Dominguez-Castro ◽  
Thomas Frauenheim
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Gold Nanoclusters ◽  
Tight Binding ◽  
Time Dependent ◽  
Effective Strategy ◽  
Dynamics Simulations ◽  
Dependent Density

Theoretical calculations are an effective strategy to comple- ment and understand experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach...

scholarly journals Bound states of a Klein–Gordon particle in the presence of a smooth potential well

2020 ◽  
Vol 35 (23) ◽  
pp. 2050140
Author(s):  
Eduardo López ◽  
Clara Rojas
Keyword(s):  
Bound States ◽  
Gordon Equation ◽  
Bound State ◽  
Potential Well ◽  
One Dimensional ◽  
Smooth Potential ◽  
Klein Gordon ◽  
The One ◽  
Potential Parameters ◽  
Klein Gordon Equation

We solve the one-dimensional time-independent Klein–Gordon equation in the presence of a smooth potential well. The bound state solutions are given in terms of the Whittaker [Formula: see text] function, and the antiparticle bound state is discussed in terms of potential parameters.

Sign in / Sign up

Export Citation Format

Share Document