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Showing papers on "Stark effect published in 1990"


Journal ArticleDOI
TL;DR: A critical review of the available experimental data on Stark widths and shifts for spectral lines of non-hydrogenic neutral atoms and positive ions has been carried out in this article.
Abstract: A critical review of the available experimental data on Stark widths and shifts for spectral lines of non‐hydrogenic neutral atoms and positive ions has been carried out. The review covers the period from 1983 through the end of 1988 and represents a continuation of earlier critical reviews up to 1982. Data tables containing the selected experimental Stark broadening parameters are presented with estimated accuracies. Guidelines for the accuracy estimates have been done developed during the previous reviews and are summarized. The data are arranged according to elements and spectra, and these are presented in alphabetical and numerical order, respectively. Comparisons with comprehensive calculations based either on the semiclassical theory, or—for multiply ionized atoms—on the modified semiempirical approximation, are made whenever possible, since the comparison with theory has often been a principal motivation for the experiments.

317 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reported the first direct demonstration of a strain-generated built-in electric field in a (111) oriented strained-layer heterostructure, where the misfit strain in a lattice mismatched quantum well was exploited to generate a longitudinal electric field via the piezoelectric effect.
Abstract: We report the first direct demonstration of a strain‐generated built‐in electric field in a (111) oriented strained‐layer heterostructure. We present a model which describes the accommodation of the misfit strain in a lattice‐mismatched quantum well, and the resulting generation of a longitudinal electric field via the piezoelectric effect. On a (111)B GaAs substrate, we grew the quantum well in the intrinsic region of a p‐i‐n diode such that the strain‐generated electric field in the quantum well opposes the weaker built‐in electric field of the diode. Under reverse bias operation, photoconductivity measurements show a quadratic blue shift of the quantum well electroabsorption peaks, in contrast to the red shifts normally observed in the quantum‐confined Stark effect. The measured blue shifts demonstrate an electric field strength of 1.7×105 V/cm, which agrees with theory to within the accuracy of the measured sample characteristics.

183 citations


Journal ArticleDOI
TL;DR: In this article, a tunable infrared modulator and/or switch using intersubband Stark shift in a step quantum well is discussed, which utilizes the inter-band absorption and the large change of separation between energy levels under an applied electric field.
Abstract: A tunable infrared modulator and/or switch using intersubband Stark shift in a step quantum well is discussed. The device utilizes the intersubband absorption and the large change of separation between energy levels in the step quantum well under an applied electric field. The incident infrared beam on the device is either absorbed or transmitted depending on the energy separation of the levels, and thus the modulation can be achieved by adjusting the energy levels with an applied electric field. The extremely short lifetime of the intersubband transition makes this modulator suitable for application in high-speed long-wavelength optical communications. >

129 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied the Stark effect involving the spin transition in the 3 A ground state of the N-V defect center in type Ib diamond, using techniques for optical detection of spin echoes.

126 citations


Journal ArticleDOI
TL;DR: Spectroscopic measurements of fluorescence and absorption in an erbium-doped fiber permit the evaluation of the Stark-level energies of the (4I(15/2) and (4)I(13/ 2) manifolds in Er:glass.
Abstract: Spectroscopic measurements of fluorescence and absorption in an erbium-doped fiber permit the evaluation of the Stark-level energies of the (4)I(15/2) and (4)I(13/2) manifolds in Er:glass. The data permit the allocation of the individual laser transitions associated with the room-temperature gain spectrum of erbium-doped fiber amplifiers operating near lambda = 1.53 microm.

126 citations


Journal ArticleDOI
TL;DR: In this paper, the Stark level-crossing spectra of S0 D2CO were analyzed for evidence of energy level correlations and quantum ergodicity, and the analysis for short and long range level correlations gave an apparent energy level spacing distribution which lies between the Poisson and GOE limits.
Abstract: The Stark level‐crossing spectra of S0 D2CO are analyzed for evidence of energy level correlations and quantum ergodicity. The analysis for short and long range level correlations gives an apparent energy level spacing distribution which lies between the Poisson and GOE limits. However, the Stark level‐crossing method diminishes any existing correlations. The true level spacing distribution must be closer to the Gaussian orthogonal ensemble (GOE) than to the Poisson limit. Complete distributions of S1−S0 coupling matrix elements and S0 dissociation rates are reported and subjected to statistical tests for ergodicity. The distribution of S1−S0 coupling matrix elements indicates that the dynamics of intramolecular vibrational redistribution of energy (IVR) is very nearly quantum ergodic. There is strong coupling and free flow of energy among vibrational degrees of freedom in this molecule above its dissociation threshold. The average S0 decay rate can be accounted for by RRKM theory with tunneling correctio...

124 citations


Journal ArticleDOI
Walter Hunziker1
TL;DR: In this article, Balslev-Combes resonance is used to construct metastable bound states with exponential decay in time governed by the complex resonance energies, up to a background of order 2N in the perturbation parameter.
Abstract: Resonances which appear as perturbed bound states are discussed in the framework of Balslev-Combes theory. The corresponding metastable states are constructed using the formal perturbation expansion to orderN−1 for the (nonexistent) perturbed bound states. They are shown to have exponential decay in time governed by the complex resonance energies, up to a background of order 2N in the perturbation parameter. The results apply in lowest orderN=1 to the perturbation of bound states embedded in the continuum and in arbitrary order to cases like the Stark effect.

100 citations


Journal ArticleDOI
TL;DR: In this article, the rotation constants of the benzene-h 6 -argon and benzene d 6-argon complexes were measured with a pulsed nozzle-beam, Fabry-Perot cavity, Fourier transform microwave spectrometer.

100 citations


Journal ArticleDOI
TL;DR: The full semiconductor Bloch equations are solved to analyze the ultrafast exciton dynamics in semiconductors, and transient adiabatic following is obtained for large detunings and arbitrary intensities, leading to exciton Stark shift, bleaching, and recovery on the time scale of the pump pulse.
Abstract: The full semiconductor Bloch equations are solved to analyze the ultrafast exciton dynamics in semiconductors. Transient adiabatic following is obtained for large detunings and arbitrary intensities, leading to exciton Stark shift, bleaching, and recovery on the time scale of the pump pulse. The many-body Coulomb effects strongly influence the semiconductor response for resonant excitation conditions, almost doubling the effective Rabi frequency of the applied field

89 citations


Journal ArticleDOI
TL;DR: A model for calculating the profile of spectral lines emitted by multielectron emitters in a hot plasma by using the static ion approximation and an impact approximation for the electrons and the Stark broadening is described.
Abstract: A model for calculating the profile of spectral lines emitted by multielectron emitters in a hot plasma is described. The Stark broadening is included in the model by using the static ion approximation and an impact approximation for the electrons. The atomic data required for the line-shape calculation are extracted from an atomic structure code and prepared as data necessary for the excited and ground levels of the radiative transition. For the cases where electron broadening is much smaller than the average ionic Stark shift, an approximation is proposed to obtain rapidly a diagonal form of the evolution operator for the emitter. Line shapes of lithiumlike and berylliumlike ions have been calculated under the conditions of recent experiments performed in laser-produced plasmas.

87 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a combination of laser frequency-modulation absorption spectroscopy and either Stark, longitudinal ultrasonic, or transverse ultrasonic internal modulation to detect persistent spectral holes in the pentacene/p-terphenyl system.
Abstract: With the use of a combination of laser frequency-modulation absorption spectroscopy and either Stark, longitudinal ultrasonic, or transverse ultrasonic internal modulation, the optical absorption spectrum of a single impurity molecule of pentacene in a p-terphenyl crystal may be measured at liquid helium temperatures. The general properties of this detection method are illustrated by first applying the technique to the detection of persistent spectral holes in the pentacene/p-terphenyl system. Selection of a single absorber for measurement is accomplished by tuning the probing laser far out into the wings of the inhomogeneously broadened O-O absorption lines for either the O{sub 1} or O{sub 2} sites. The single-molecule line shape is similar to that predicted by a simple model of the double-modulation process. The approximate amplitude of the single-molecule signals suggests that triplet bottleneck power broadening is suppressed far out in the wings of the inhomogeneous line. This work probes the ultimate N = 1 limit of the statistical fine structure present in all inhomogeneous absorption lines.

Journal ArticleDOI
TL;DR: In this paper, the ground state of CO2 at its equilibrium geometry was calculated from the fourth-order many-body perturbation theory energies of CO 2 in the presence of various configurations of point charges.
Abstract: The dipole (α), quadrupole (C), and dipole–octopole (E) polarizabilities, the dipole–dipole–quadrupole (B) and second dipole (γ) hyperpolarizabilities, and the quadrupole (θ) and hexadecapole (Φ) moments are calculated for the ground state of CO2 at its equilibrium geometry. The values are obtained from fourth‐order many‐body perturbation theory energies of CO2 in the presence of various configurations of point charges. Electron correlation affects the longitudinal components more than the transverse ones; hence, electron correlation effects are greater for the anisotropies than for the isotropic averages of these properties. Our best vibrationless estimates for the isotropic values are ᾱ≂17.63 e2a20E−1h, C≂77.8 e2a40E−1h, B≂−2.1×102 e3a40E−2h, γ≂1.20×103 e4a40E−3h, and θzz≂−3.24 ea20. The quadrupole moment, mean dipole polarizability and hyperpolarizability are in satisfactory agreement with experiment. On the other hand, the polarizability anisotropy Δα≂14.3 e2a20E−1h agrees with experimental estimat...

Journal ArticleDOI
TL;DR: In this article, a single point, spatially scannable, high-sensitivity polarimeter installed on DIII-D is described, with good temporal and spatial resolution.
Abstract: Motional Stark effect produces large net linear polarization of Hα emission from neutral beams in tokamaks. Measurement of the polarization direction permits determination of the local magnetic field pitch angle. Design of a single point, spatially scannable, high‐sensitivity polarimeter installed on DIII‐D is described. Excellent signal‐to‐noise ratio with good temporal and spatial resolution was obtained in preliminary measurements of magnetic field pitch angle.

Journal ArticleDOI
TL;DR: An anticrossing behavior between certain exciton states is observed if the electric field perpendicular to the layers of the superlattice is such that the energy spacing between the lowest two conduction subbands is an integer multiple of the Stark-ladder spacing.
Abstract: We report on novel interaction phenomena between different Stark ladders in a strongly coupled GaAs-AlAs superlattice. We observe an anticrossing behavior between certain exciton states if the electric field perpendicular to the layers of the superlattice is such that the energy spacing between the lowest two conduction subbands is an integer multiple of the Stark-ladder spacing. This anticrossing is accompanied by a spatial delocalization of the electron states and can therefore be resolved by photocurrent spectroscopy. Our experimental results are confirmed by a numerical calculation of the field dependence of the conduction-subband energies.

Journal ArticleDOI
TL;DR: The first calculation of the energies and absorption spectra of GaAs/Ga 0.65 Al 0.35 As superlattice excitons in the presence of an applied electric field differs substantially from the single-particle Stark-ladder results, particularly at low field strengths.
Abstract: We present the first calculation of the energies and absorption spectra of GaAs/${\mathrm{Ga}}_{0.65}$${\mathrm{Al}}_{0.35}$As superlattice excitons in the presence of an applied electric field. The resulting spectra differ substantially from the single-particle Stark-ladder results, particularly at low field strengths. We find very good agreement with the experimental photocurrent spectra of Agull\'o-Rueda, Mendez, and Hong [Phys. Rev. B 40, 1357 (1989)], and suggest other superlattice structures to test the quantum coherence of the exciton wave functions.

Journal ArticleDOI
TL;DR: Results indicate that SCCF contributions yield modest improvement in the calculated value of the overall crystal-field splitting of the energy levels.
Abstract: nets Y3A1)012 (YAG), Y3Sc~A1,0„(YSAG), Gd3Sc~Ga30l2 (GSGG), and LagLu2Ga30]2 (LLGG). The majority of Nd'+ ions substitute for Y'+, Gd'+, or La'+ ions in sites of D2 point-group symmetry in the lattice. Individual Stark levels within each manifold have been identified experimentally up to 40000 cm ' and compared with results obtained from a theoretical calculation. The model Hamiltonian includes Coulombic, spin-orbit, and interconfiguration interaction terms for the 4f atomic configuration of Nd'+ and crystal-field terms in D2 symmetry, including spin-correlated crystal-field (SCCF) contributions. The Hamiltonian was diagonalized within the complete 4f SLJMJ basis set which includes 364 states. Comparison between 148 (Nd: YAG), 140 (Nd: YSAG), 143 (Nd:GSGG), and 107 (Nd:LLGG) observed and calculated Stark levels (without SCCF) yields rms deviations of 18, 19, 17, and 16 cm, respectively. Results indicate that SCCF contributions yield modest improvement in the calculated value of the overall crystal-field splitting of the energy levels.

Journal ArticleDOI
TL;DR: In this article, the motional Stark effect was employed in a novel technique for obtaining the pitch angle profile and q(r) using polarimetry measurements of the Doppler shifted Hα emission from a hydrogen diagnostic neutral beam.
Abstract: The Stark effect has been employed in a novel technique for obtaining the pitch angle profile and q(r) using polarimetry measurements of the Doppler shifted Hα emission from a hydrogen diagnostic neutral beam. As a neutral beam propagates through a plasma, collisions of the beam particles with the background ions and electrons will excite beam atoms, leading to emission of radiation. The motional Stark effect, which arises from the electric field induced in the atom’s rest frame due to the beam motion across the magnetic field (E=Vbeam×B), causes a wavelength splitting of several angstroms and polarization of the emitted radiation. The Δm=±1 transitions, or σ components, from the beam fluorescence are linearly polarized parallel to the direction of the local magnetic field when viewed transverse to the fields. Since the hydrogen beam provides good spatial localization and penetration, the pitch angle can be obtained anywhere in the plasma. A photoelastic modulator (PEM) is used to modulate the linearly polarized light. Depending on the orientation of the PEM, it can measure the sine or cosine of the angle of polarization. Two PEM’s are used to measure both components simultaneously. Results of q(r) for both Ohmic and NBI heated discharges have been obtained in the Princeton Beta Experiment (PBX‐M) tokamak, with an uncertainty of ∼6% for q(0).The Stark effect has been employed in a novel technique for obtaining the pitch angle profile and q(r) using polarimetry measurements of the Doppler shifted Hα emission from a hydrogen diagnostic neutral beam. As a neutral beam propagates through a plasma, collisions of the beam particles with the background ions and electrons will excite beam atoms, leading to emission of radiation. The motional Stark effect, which arises from the electric field induced in the atom’s rest frame due to the beam motion across the magnetic field (E=Vbeam×B), causes a wavelength splitting of several angstroms and polarization of the emitted radiation. The Δm=±1 transitions, or σ components, from the beam fluorescence are linearly polarized parallel to the direction of the local magnetic field when viewed transverse to the fields. Since the hydrogen beam provides good spatial localization and penetration, the pitch angle can be obtained anywhere in the plasma. A photoelastic modulator (PEM) is used to modulate the linearly po...

Journal ArticleDOI
TL;DR: In this paper, large Stark shifts of intersubband transitions in a step quantum well are observed for the first time, which can be exploited for the fabrication of optical modulators operating in the range from mid to far infrared.
Abstract: Large Stark shifts of intersubband transitions in a step quantum well are observed for the first time. The Stark shifts are ∼8 and 7 meV at ∼18 kV/cm for the 1→2 and 1→3 intersubband transitions, respectively, while the Stark shift of a similar transition in a square quantum well is only about 0.5 meV under the same bias condition. The intersubband transitions in step quantum wells can be either red or blue Stark shifted depending on the direction of the applied electric field. The large Stark shifts of intersubband transitions in the step quantum wells can be exploited for the fabrication of optical modulators operating in the range from mid to far infrared.

Journal ArticleDOI
TL;DR: In this article, the effect of external electric field on the absorption spectrum of CdS and CdSe microcrystals has been investigated both experimentally and theoretically, and it is found that electro-optic properties of the microcrystal doped glasses near the interband edge are governed by the quadratic Stark effect.

Journal ArticleDOI
TL;DR: In this paper, the rotational spectra of cyclohexane-1,1-d 2, cycloencoder-13 C-1.1, 1.2, 2, 3, 3.3, 6.5, 7.1 GHz with a pulsed microwave Fourier transform spectrometer have been measured.
Abstract: The rotational spectra of cyclohexane-1,1-d 2 , cyclohexane- 13 C-1,1-d 2 , cyclohexane-d 1 (equatorial and axial), and cyclohexane-1,1,2,2,3,3-d 6 have been measured between 8 and 26 GHz with a pulsed microwave Fourier transform spectrometer. From their analysis the rotational constants and the quartic centrifugal distortion constants have been determined. The complete substitution structure has been deduced from these rotational constants. Measurements of the Stark effect have provided information on the dipole moment induced by deuterium substitution

Journal ArticleDOI
TL;DR: In this article, the transversale relaxation of excitons in the dynamical Stark effect is treated on a microscopic level within a density-matrix approach explaining the strongly suppressed damping for the off-resonant pump pulse.
Abstract: The transverse relaxation of excitons in the dynamical Stark effect is treated on a microscopic level within a density-matrix approach explaining the strongly suppressed damping for the off-resonant pump pulse. An expression for the differential transmission spectrum is derived including the dependence on pump- and test polarization. Calculations for CdS with its three exciton series are given. Die transversale Relaxation von Exzitonen im dynamischen Starkeffekt wird auf mikroskopischem Niveau im Rahmen einer Dichtematrixmethode behandelt und erklart die stark unterdruckte Dampfung fur nichtresonante Pumpimpulse. Ein Ausdruck fur das differentielle Transmissionsspektrum wird abgeleitet, der die Abhangigkeit von Pump und Testpolarisation einschliest. Berechnungen werden fur CdS mit seinen drei Exzitonenserien angegeben.

Journal ArticleDOI
J.E. Zucker1, T. Y. Chang1, M. Wegener1, N.J. Sauer1, K.L. Jones1, Daniel S. Chemla1 
TL;DR: In this paper, measurements of electrorefraction and electroabsorption in a multiple-quantum-well waveguide structure in which each InGaAs quantum well is provided with an individual electron reservoir are presented.
Abstract: Measurements of electrorefraction and electroabsorption in a multiple-quantum-well waveguide structure in which each InGaAs quantum well is provided with an individual electron reservoir are presented. External bias transfers electrons into the wells, thus quenching the absorption and producing a refractive index change at wavelengths below the bandedge which is linear in the applied voltage. It is shown that in this type of structure both the change in refractive index per applied field and the ratio of optical phase to intensity modulation can be significantly enhanced over those found in the quantum confined Stark effect. >

Journal ArticleDOI
TL;DR: The observation of an exciton redshift with a below-gap laser beam, linked to the presence of a bound two-pair state in CuCl, demonstrates the importance of the biexciton in the description of the optical Stark effect.
Abstract: We report the observation of an exciton redshift with a below-gap laser beam, linked to the presence of a bound two-pair state in CuCl. This change in the shift direction for the optical Stark effect in semiconductors relies upon the predominant creation of virtual biexcitons, as shown by the polarization selection rules. Our experiment demonstrates the importance of the biexciton in the description of the optical Stark effect.

Journal ArticleDOI
TL;DR: In this paper, the authors have studied CO on Pt(335) using infrared diode laser spectroscopy and electric field modulation and found that the tuning rate of terrace CO is at least an order of magnitude smaller than expected.

Journal ArticleDOI
TL;DR: The influence of the resonant intermediate states is seen in the total ionization rate as well as the photoelectron spectrum, and nonlinear ac Stark shifts are found at higher intensities.
Abstract: We have developed a new method and the necessary numerical procedures to solve the time-dependent Schroedinger equation for an atom in intense laser fields. This method allows us to obtain not only the total ionization rate, but also the emitted photoelectron spectrum. We report nonperturbative calculations at high intensity with extensions of the method to systems including a realistic pulse shape. The influence of the resonant intermediate states is seen in the total ionization rate as well as the photoelectron spectrum, and nonlinear ac Stark shifts are found at higher intensities.

Journal ArticleDOI
TL;DR: The effect of an electric field has been measured on the absorption spectrum (Stark effect) of the heterodimer mutant (M)H202L of Rhodobacter sphaeroides reaction centers, where the primary electron donor consists of one bacteriochlorophyll alpha and one bacteriopheophytin alpha.
Abstract: The effect of an electric field has been measured on the absorption spectrum (Stark effect) of the heterodimer mutant (M)H202L of Rhodobacter sphaeroides reaction centers, where the primary electron donor consists of one bacteriochlorophyll alpha and one bacteriopheophytin alpha. The electronic absorption spectrum of the heterodimer mutant from 820-950 nm is relatively featureless in a poly(vinyl alcohol) film, but it exhibits some structure in a glycerol/water glass at 77 K. A feature is seen in the Stark effect spectrum of the heterodimer at 77 K centered at 927 and 936 nm in poly(vinyl alcohol) and a glycerol/water glass, respectively. This feature has approximately the same shape and width as the Stark effect for the primary electron donor of the wild type, which consists of a pair of bacteriochlorophyll alpha molecules. The angle zeta A between the transition moment at the frequency of absorption and the difference dipole delta muA is 36 +/- 2 degrees in the wild type and 32 +/- 2 degrees for that feature in the heterodimer. A range of values for [delta muA] = (13-17)/f Debye units (where f is the local field correction) is obtained for the 936-nm feature in glycerol/water, depending on analysis method. This feature is interpreted as arising from a transition to the lower exciton state of the heterodimer, which is more strongly mixed with a low-lying charge transfer transition than in the wild type.

Journal ArticleDOI
TL;DR: In this article, the parabolic quantum well (PQW) has been analyzed both analytically and numerically, and it has been shown that the fundamental absorption edge shift in PQWs is proportional to the square of the well width and that the Stark shift is independent of the particle mass.
Abstract: Quantum-confined Stark effect in parabolic quantum well (PQW) has been analyzed both analytically and numerically. Analytical studies have revealed that the fundamental absorption edge shift in PQWs is proportional to the square of the well width, and that the Stark shift in PQWs is independent of the particle mass. From numerical calculations, it has been confirmed that PQW structure enables us more easily than rectangular quantum well to obtain the absorption-type optical waveguide switches whose characteristics are nearly polarization-independent, and that PQW is also advantageous if we intend to obtain the polarization-independent changes in the refractive index with low field and over a wide wavelength region. In addition, an equivalent PQW structure has been fabricated, and the mass-independent Stark shift of the PQW has been observed for the first time.

Journal ArticleDOI
TL;DR: In this article, a GaAs/AlGaAs multiple quantum well nonlinear directional coupler using femtosecond pulses was observed at room temperature in GaAs and AlGaAs.
Abstract: All‐optical modulation is observed at room temperature in a GaAs/AlGaAs multiple quantum well nonlinear directional coupler using femtosecond pulses. The origin of the ultrafast (<500 fs) recovery of the device is attributed to the optical Stark effect.

Journal ArticleDOI
TL;DR: In this paper, the permanent dipole moment of TiN was determined from the complete resolution of the first and second-order Stark splitting of the Q21(1.5)+R2(0.5) line of the (0,0) band of the A 2Π-X 2Σ+ system.
Abstract: The permanent dipole moment of TiN in its X 2Σ+ and A 2Σ states has been determined from the complete resolution of the first‐ and second‐order Stark splitting of the Q21(1.5)+R2(0.5) line of the (0,0) band of the A 2Π–X 2Σ+ system. Values of 3.56±0.05 D (2σ) and 4.63±0.04 D (2σ) have been derived for the X and A states respectively, from least‐squares fits to plots of Stark splitting vs electric field strength. Electric fields up to 12 kV/cm have been employed avoiding voltage breakdown. The zero‐field spectrum shows resolution of the nuclear magnetic hyperfine structure of the 47TiN and 49TiN isotopes. This hyperfine structure is that of the ground X 2Σ+ state only and is shown to follow closely the coupling case bβS. The value of the Fermi contact parameter is −570 MHz which implies a 4s occupation of the 9σ molecular orbital (MO) of 72%. The results are compared with calculated and available experimental values for early first‐row transition metal oxides and nitrides.

Journal ArticleDOI
TL;DR: Calcul du coefficient de transmission par la methode de matrice de transfert de ces resonances et l'interference de type Fabry-Perot.
Abstract: We discuss the existence of electromagnetic Stark ladder in some optic systems by studying the propagation of light. The transmission coefficient is calculated by means of the transfer-matrix method. It is shown that although the transfer matrix is different from the quantum case it can give, in some particular configurations, a Stark-ladder resonance structure similar to the one observed in quantum systems. The relation between these resonances and a Fabry-Perot-like interference is discussed. Consideration is given to the observability of these ladders in the laboratory.