Showing papers on "Stark effect published in 2005"
TL;DR: In this paper, the authors proposed a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of selfabsorption on line intensity.
260 citations
TL;DR: In this paper, the magnitude of the longitudinal electric field induced by both spontaneous and piezoelectric polarizations was determined by comparing experimental results with a variational calculation of excitonic energies and oscillator strengths.
Abstract: Continuous-wave, time-integrated, and time-resolved photoluminescence experiments are used to study the excitonic optical recombinations in wurtzite ZnO/Zn078Mg022O quantum wells of varying widths By comparing experimental results with a variational calculation of excitonic energies and oscillator strengths, we determine the magnitude (09MV∕cm) of the longitudinal electric field that is induced by both spontaneous and piezoelectric polarizations The quantum-confined Stark effect counteracts quantum confinement effects for well widths larger than 3nm, leading to emission energies that can lie 05eV below the ZnO excitonic gap and to radiative lifetimes that can be larger than milliseconds
206 citations
TL;DR: Analysis of the dephasing mechanisms reveals dipole selection rules closely analogous to those seen in atomic spectroscopy experiments, which suggest the prospects for exploiting them for scalable quantum information processing applications are more promising than previous dephase models would have predicted.
Abstract: Resonant optical coupling experiments have demonstrated coherent quantum interference between the Stark-split ``dressed states'' of a synthesized 3-level electronic system in a semiconductor quantum well. Analysis of the dephasing mechanisms reveals dipole selection rules closely analogous to those seen in atomic spectroscopy experiments. In this respect, these systems behave as ``artificial atoms'' for the purposes of observing a range of nonclassical coherent optical effects. The prospects for exploiting them for scalable quantum information processing applications are more promising than previous dephasing models would have predicted.
196 citations
TL;DR: The observed giant Stark effect significantly reduces the band gap of BNNTs and thus greatly enhances the utility of BnnTs for nanoscale electronic, electromechanical, and optoelectronic applications.
Abstract: Bias dependent scanning tunneling microscopy and scanning tunneling spectroscopy have been used to characterize the influence of transverse electric fields on the electronic properties of boron-nitride nanotubes (BNNTs). We find experimental evidence for the theoretically predicted giant Stark effect. The observed giant Stark effect significantly reduces the band gap of BNNTs and thus greatly enhances the utility of BNNTs for nanoscale electronic, electromechanical, and optoelectronic applications.
179 citations
TL;DR: In this paper, an initial temperature of 3.2 eV and density of 7.7×1017 cm−3 were measured using Boltzmann diagram method using singly ionized Sn lines, while density measurements were made using the Stark broadening method.
Abstract: Optical emission spectroscopic studies have been carried out on a tin plasma generated using 1064-nm, 8-ns pulses from a Nd:yttrium aluminum garnet laser. Temperature and density were estimated from the analysis of spectral data. The temperature measurements have been performed by Boltzmann diagram method using singly ionized Sn lines, while density measurements were made using the Stark broadening method. An initial temperature of 3.2 eV and density of 7.7×1017cm−3 were measured. Temporal and spatial behaviors of electron temperature and density in the laser-generated tin plasma have been analyzed. Time evolutions of density and temperature are found to decay adiabatically at early times. The spatial variation of density shows approximately 1∕z dependence. The time-integrated temperature exhibits an appreciable rise at distances greater than 7 mm. This may be caused by the deviation from local thermodynamic equilibrium at larger distances from the target surface.
156 citations
TL;DR: In this paper, the influence of an external electric field on the optical properties of single quantum dots is investigated and a large decrease of the anisotropic exchange splitting, correlated with the in-plane Stark shift, is observed.
Abstract: The influence of an in-plane electric field on the optical properties of single quantum dots is investigated. On a sample containing a plane of InAs∕GaAs dots, micrometer-size electro-optical structures were produced in order to apply an external electric field in the dot plane. A large decrease of the anisotropic exchange splitting, correlated with the in-plane Stark shift, is observed.
140 citations
TL;DR: In this article, the authors performed optical emission spectroscopy measurements with added trace probe gases in an atmospheric pressure direct current helium microplasma to investigate the electric field distribution in the cathode sheath region.
Abstract: Optical emission spectroscopy measurements were performed with added trace probe gases in an atmospheric pressure direct current helium microplasma. Spatially resolved measurements (resolution ~6 µm) were taken across a 200 µm slot-type discharge. Gas temperature profiles were determined from N2 emission rotational spectroscopy. Stark splitting of the hydrogen Balmer-β line was used to investigate the electric field distribution in the cathode sheath region. Electron densities were evaluated from the analysis of the spectral line broadening of Hβ emission. The gas temperature was between 350 and 550 K, peaking nearer the cathode and increasing with power. The electron density in the bulk plasma was in the range (4–7) × 1013 cm−3. The electric field peaked at the cathode (~60 kV cm−1) and decayed to small values over a distance of ~50 µm (sheath edge) from the cathode. These experimental data were generally in good agreement with a self-consistent one-dimensional model of the discharge.
126 citations
TL;DR: In this article, the electron density in dielectric barrier discharge is measured by using the spectral line profile method and the asymmetrical deconvolution is used to obtain Stark broadening.
Abstract: We present a method and results for measurement of electron density in atmospheric-pressure dielectric barrier discharge. The electron density of microdischarge in atmospheric pressure argon is measured by using the spectral line profile method. The asymmetrical deconvolution is used to obtain Stark broadening. The results show that the electron density in single filamentary microdischarge at atmospheric pressure argon is 3.05×1015cm−3 if the electron temperature is 10 000 K. The result is in good agreement with the simulation. The electron density in dielectric barrier discharge increases with the increase of applied voltage.
109 citations
TL;DR: A continuously operated electrostatic trap for polar molecules is demonstrated that offers good starting conditions for high-precision measurements, and can be used as a first stage in cooling schemes for molecules and as a "reaction vessel" in cold chemistry.
Abstract: A continuously operated electrostatic trap for polar molecules is demonstrated. The trap has a volume of approximately 0.6 cm3 and holds molecules with a positive Stark shift. With deuterated ammonia from a quadrupole velocity filter, a trap density of approximately 10(8) cm(-3) is achieved with an average lifetime of 130 ms and a motional temperature of approximately 300 mK. The trap offers good starting conditions for high-precision measurements, and can be used as a first stage in cooling schemes for molecules and as a "reaction vessel" in cold chemistry.
101 citations
TL;DR: In this paper, the Stark-chirped rapid adiabatic passage (SCRAP) technique was used for complete population transfer between two quantum states, in which a strong far-off-resonant pulse modifies the transition frequencies by inducing dynamic Stark shifts and thereby creating time-dependent level crossings amongst the three diabatic states.
Abstract: We show that the technique of Stark-chirped rapid adiabatic passage SCRAP, hitherto used for complete population transfer between two quantum states, offers a simple and robust method for complete population transfer amongst three states in atoms and molecules. In this case SCRAP uses three laser pulses: a strong far-off-resonant pulse modifies the transition frequencies by inducing dynamic Stark shifts and thereby creating time-dependent level crossings amongst the three diabatic states, while near-resonant and moderately strong pump and Stokes pulses, appropriately offset in time, drive the population between the initial and final states via adiabatic passage. The population transfer efficiency is robust to variations in the intensities of the lasers, as long as these intensities are sufficiently large to enforce adiabatic evolution. With suitable pulse timings the population in the possibly decaying intermediate state can be minimized, as with stimulated Raman adiabatic passage STIRAP. This technique applies to one-photon as well as multiphoton transitions and it is also applicable to media exhibiting inhomogeneous broadening; these features represent clear advantages over STIRAP by overcoming the inevitable dynamical Stark shifts that accompany multiphoton transitions as well as unwanted detunings, e.g., induced by Doppler shifts.
66 citations
TL;DR: In this paper, a detailed variational calculation of the binding energies of hydrogenic impurities in a cubic quantum box as a function of both the impurity position and an applied electric field was carried out.
Abstract: We carry out a detailed variational calculation of the binding energies of hydrogenic impurities in a cubic quantum box as a function of both the impurity position and an applied electric field. It is found that the binding energy of the impurities is highly dependent on the impurity position, and the electric field splits the energy of impurities on points of the box which are equivalent in the absence of the electric field. When the impurity is located at the upper half of the cube and the field pushes the particle downwards, then the binding energy decreases, whereas the Stark shift exhibits a minimum.
TL;DR: In this paper, the effect of an externally applied lateral electric field upon an exciton confined in a single InGaN quantum dot was studied using microphotoluminescence spectroscopy.
Abstract: The effect of an externally applied lateral electric field upon an exciton confined in a single InGaN quantum dot is studied using microphotoluminescence spectroscopy. The quantum-confined Stark effect causes a shift in the exciton energy of more than 5 meV, accompanied by a reduction in the exciton oscillator strength. The shift has both linear and quadratic terms as a function of the applied field.
TL;DR: To determine the magnitude and direction of the internal electric field in the Xe4 cavity of myoglobin mutant L29W-S108L, the vibrational Stark effect of carbon monoxide (CO) is studied using infrared spectroscopy at cryogenic temperatures.
TL;DR: In this paper, an extended description of phase stability in a Stark decelerator is given, including higher-order effects, which predicts a wide variety of resonances that originate from the spatial and temporal periodicity of the electric fields.
Abstract: The motion of polar molecules can be controlled by time-varying inhomogeneous electric fields. In a Stark decelerator, this is exploited to select a fraction of a molecular beam that is accelerated, transported, or decelerated. Phase stability ensures that the selected bunch of molecules is kept together throughout the deceleration process. In this paper an extended description of phase stability in a Stark decelerator is given, including higher-order effects. This analysis predicts a wide variety of resonances that originate from the spatial and temporal periodicity of the electric fields. These resonances are experimentally observed using a beam of OH ({sup 2}{pi}{sub 3/2},v=0,J=3/2) radicals passing through a Stark decelerator.
TL;DR: In this paper, a theoretical investigation of the combined effect of confinement geometry, valley degeneracy, crystallo-graphic orientations, and anisotropy of the effective mass on the intraband absorption of the conduction band of Si nanocrystals is presented.
Abstract: Received 3 May 2005; published 27 October 2005A theoretical investigation of the combined effect of confinement geometry, valley degeneracy, crystallo-graphic orientations, and anisotropy of the effective mass on the intraband absorption of the conduction bandof Si nanocrystals is presented. We show that the coupling between the nanocrystal shape and arbitraryorientations of the crystalline Si core plays a dramatic role in the intraband optical properties through inter-esting changes in the electronic structure and intra- and inter-valley degeneracy. Different orientations of thecrystalline Si also affect the shape and orientation of the orbital wave functions, thereby modifying transitionrules and fine structure of the intraband absorption. The anisotropy of the effective mass is also responsible forthe emergence of absorption peaks that are not present in isotropic nanocrystals. Additional intraband transi-tions are also induced by changes in the nanocrystal shape with respect to spherical dots. Moreover, thequantum confined Stark effect blueshifts the absorption peaks and induces the appearance of peak structures asa consequence of the relaxation of selection rules caused by the displacement of the wave functions in responseto external electric fields. This effect was found to be only appreciable in large nanocrystals.DOI: 10.1103/PhysRevB.72.155438 PACS number s : 73.21.La, 73.22.Dj, 78.67.Bf, 78.20.Bh
TL;DR: In this article, the authors studied the nonlinear behavior of an electromagnetically induced transparency EIT resonance subject to a coherent driving field and showed that the doublet splitting originates from the rf-field induced dynamic Stark effect and has close analogy with the Autler-Townes effect observed in three-level pump-probe spectroscopy study.
Abstract: In this paper we study the nonlinear behavior of an electromagnetically induced transparency EIT resonance subject to a coherent driving field. The EIT is associated with a three-level system where two hyperfine levels within an electronic ground state are coupled to a common excited state level by a coupling field and a probe field. In addition there is an radio-frequency rf field driving a hyperfine transition within the ground state. The paper contrasts two different situations. In one case the rf-driven transition shares a common level with the probed transition and in the second case it shares a common level with the coupled transition. In both cases the EIT resonance is split into a doublet and the characteristics of the EIT doublet are determined by the strength and frequency of the rf-driving field. The doublet splitting originates from the rf-field induced dynamic Stark effect and has close analogy with the Autler-Townes effect observed in three-level pump-probe spectroscopy study. The situation changes when the rf field is strong and the two cases are very different. One is analogous to two three-level systems with EIT resonance associated with each. The other corresponds to a doubly driven three-level system with rf-field-induced electromagnetically induced absorption resonance. The two situations are modeled using numerical solutions of the relevant equation of motion of density matrix. In addition a physical account of their behaviors is given in terms of a dressed state picture.
TL;DR: An effective mass theory for substitutional donors in silicon in an inhomogeneous environment is developed and the ground state energy for the donor electron is found to increase with electric field as a consequence of spectrum narrowing of the 1s manifold.
Abstract: We develop an effective mass theory for substitutional donors in silicon in an inhomogeneous environment. Valley-orbit coupling is included perturbatively. We specifically consider the Stark effect in $\mathrm{Si}\ensuremath{\mathbin:}\mathrm{P}$. In this case, the theory becomes more accurate at high fields, while it is designed to give correct experimental binding energies at zero field. Unexpectedly, the ground state energy for the donor electron is found to increase with electric field as a consequence of spectrum narrowing of the $1s$ manifold. Our results are of particular importance for the Kane quantum computer.
TL;DR: In this paper, the authors show that coherent control of multiphoton transitions is possible in the strong field limit, even in the presence of large dynamic Stark shifts, by tailoring the phase of an ultrafast laser pulse, one can compensate for the dynamic Stark shift during the atom-field interaction to achieve efficient population transfer in two-photon absorption.
Abstract: We show that coherent control of multiphoton transitions is possible in the strong field limit, even in the presence of large dynamic Stark shifts. By tailoring the phase of an ultrafast laser pulse, one can compensate for the dynamic Stark shift during the atom-field interaction to achieve efficient population transfer in two-photon absorption. Numerical simulations for atomic sodium reveal efficient population transfer from the $\ensuremath{\mid}3s⟩$ ground state to the $\ensuremath{\mid}4s⟩$ excited state using an appropriately shaped ultrafast laser pulse. The theory and simulations provide insight into coherent control of more complicated multiphoton processes.
Journal Article•
TL;DR: In this paper, the Stark-chirped rapid adiabatic passage (SCRAP) technique was used for complete population transfer between two quantum states, in which a strong far-off-resonant pulse modifies the transition frequencies by inducing dynamic Stark shifts and thereby creating time-dependent level crossings amongst the three diabatic states.
Abstract: We show that the technique of Stark-chirped rapid adiabatic passage SCRAP, hitherto used for complete population transfer between two quantum states, offers a simple and robust method for complete population transfer amongst three states in atoms and molecules. In this case SCRAP uses three laser pulses: a strong far-off-resonant pulse modifies the transition frequencies by inducing dynamic Stark shifts and thereby creating time-dependent level crossings amongst the three diabatic states, while near-resonant and moderately strong pump and Stokes pulses, appropriately offset in time, drive the population between the initial and final states via adiabatic passage. The population transfer efficiency is robust to variations in the intensities of the lasers, as long as these intensities are sufficiently large to enforce adiabatic evolution. With suitable pulse timings the population in the possibly decaying intermediate state can be minimized, as with stimulated Raman adiabatic passage STIRAP. This technique applies to one-photon as well as multiphoton transitions and it is also applicable to media exhibiting inhomogeneous broadening; these features represent clear advantages over STIRAP by overcoming the inevitable dynamical Stark shifts that accompany multiphoton transitions as well as unwanted detunings, e.g., induced by Doppler shifts.
TL;DR: In this paper, the nonresonant dynamic Stark effect (NRDSE) was used for quantum control in the intermediate field strength regime (nonperturbative but nonionizing).
Abstract: The nonresonant dynamic Stark effect (NRDSE) is investigated as a general tool for quantum control in the intermediate field strength regime (nonperturbative but nonionizing). We illustrate this scheme for the case of nonadiabatic molecular photodissociation at an avoided crossing. Using the NRDSE exclusively, both the electronic branching ratio and predissociation lifetime may be controlled. Infrared control pulses are used to modify the field-free dynamical evolution during traversal of the avoided crossing, thus controlling the nonadiabatic branching ratio. Predissociation lifetimes may be either increased or decreased using properly timed short infrared pulses to modify phase differences between the diabatic wave packets. In contrast with the limiting cases of perturbative control (interference between transitions) and strong field control with ionizing laser fields, control via the NRDSE may be thought of as reversibly modifying the effective Hamiltonian during system propagation.
TL;DR: In this paper, a single-band approximation for the hole and a parabolic lateral confinement potential are adopted which allows for the separation of the lateral center-of-mass motion and consequently for an exact numerical solution of the Schrodinger equation.
Abstract: We study the Stark effect for an exciton confined in a pair of vertically coupled quantum dots. A single-band approximation for the hole and a parabolic lateral confinement potential are adopted which allows for the separation of the lateral center-of-mass motion and consequently for an exact numerical solution of the Schr\"odinger equation. We show that for intermediate tunnel coupling the external electric field leads to the dissociation of the exciton via an avoided crossing of bright and dark exciton energy levels which results in an atypical form of the Stark shift. The electric-field-induced dissociation of the negative trion is studied using the approximation of frozen lateral degrees of freedom. It is shown that in a symmetric system of coupled dots the trion is more stable against dissociation than the exciton. For an asymmetric system of coupled dots the trion dissociation is accompanied by a positive curvature of the recombination energy line as a function of the electric field.
TL;DR: The inelastic lifetimes of electrons in image-potential states at Cu(100) that are Stark shifted by the electrostatic tip-sample interaction in the scanning tunneling microscope are calculated using the many-body GW approximation.
Abstract: The inelastic lifetimes of electrons in image-potential states at Cu(100) that are Stark shifted by the electrostatic tip-sample interaction in the scanning tunneling microscope are calculated using the many-body GW approximation. The results demonstrate that in typical tunneling conditions the image state lifetimes are significantly reduced from their field-free values. The Stark shift to higher energies increases the number of inelastic scattering channels that are available for decay, with field-induced changes in the image state wave function increasing the efficiency of the inelastic scattering through greater overlap with final state wave functions.
TL;DR: In this article, asymmetric theoretical Stark profiles, which take into account the effect of static ions, were used to fit the experimental data of the emission profile of the line Fe I 538.34 nm.
TL;DR: In this paper, the Stark broadening of the H α, H β and H γ lines was used to determine the electron density and temperature in a microwave plasma at atmospheric pressure.
Abstract: For a microwave plasma at atmospheric pressure the use of the Stark broadening of the H α , H β and H γ lines to determine the electron density and temperature is reported. Knowing the values of th...
TL;DR: In this paper, cold collisions of OH molecules in the ground state, under the influence of a magnetic field, were investigated and it was shown that modest fields of several thousand gauss can act to suppress inelastic collisions of weak-field-seeking states by two orders of magnitude.
Abstract: We consider cold collisions of OH molecules in the {sup 2}{pi}{sub 3/2} ground state, under the influence of a magnetic field. We find that modest fields of several thousand gauss can act to suppress inelastic collisions of weak-field-seeking states by two orders of magnitude. We attribute this suppression to two factors: (i) an indirect coupling of the entrance and the exit channel, in contrast to the effect of an applied electric field; and (ii) the relative shift of the entrance and exit scattering thresholds. In view of these results, magnetic trapping of OH may prove feasible.
TL;DR: In this article, a 0.1% measurement of the ratio R of the ac Stark effect (or light shift) in the 6S1/2 and 5D3/2 states of a singly-ionized barium ion, iso-electronic to the well-studied alkali atom Cs, was reported.
Abstract: Experimental tests of atomic theory often involve the measurement of atomic state lifetimes, oscillator strengths, polarizabilities [1], and other properties which depend directly on atomic dipole matrix elements. Absolute measurements of these quantities can be difficult. Another approach [2] is to make high precision measurements of properties which can be directly calculated using modern atomic theory techniques and depend on ratios of atomic matrix elements. Here we report a 0.1% measurement of the ratio R of the ac Stark effect (or light shift) in the 6S1/2 and 5D3/2 states of a singly-ionized barium ion, iso-electronic to the well-studied alkali atom Cs. Comparison of this result with an ab initio calculation of R would yield a new test of atomic theory. Since R is expressible as ratios of matrix elements (shown below), this measurement also establishes a sum rule relating the barium matrix elements known to ∼ 1% or better (i.e. h 6S1/2||r||6P1/2,3/2i ) to matrix ele
TL;DR: In this paper, the ultracold scattering properties of polar molecules in strong electric field-seeking states were investigated and it was shown that the elastic cross section displays a quasiregular set of potential resonances.
Abstract: We present first steps toward understanding the ultracold scattering properties of polar molecules in strong electric field-seeking states. We have found that the elastic cross section displays a quasiregular set of potential resonances as a function of the electric field, which potentially offers intimate details about the intermolecular interaction. We illustrate these resonances in a ``toy'' model composed of pure dipoles, and in more physically realistic systems. To analyze these resonances, we use a simple WKB approximation to the eigenphase, which proves both reasonably accurate and meaningful. A general treatment of the Stark effect and dipolar interactions is also presented.
TL;DR: In this paper, the authors used the thermochromic shift method of absorption and fluorescence spectra of aniline in ethyl acetate for temperature ranging from 213 to 393 K.
TL;DR: The vibrational energy spacings, rotational constants, and spin orbit coupling constants for the first three vibrational states of F(2) (+)(X (2)Pi(g)) have been determined accurately.
Abstract: Rotationally resolved pulsed field ionization and zero electronic kinetic energy photoelectron spectra for the transition F2+(XΠg2)←F2(XΣg+1) have been recorded using the extreme ultraviolet coherence radiation. The vibrational energy spacings, rotational constants, and spin orbit coupling constants for the first three vibrational states of F2+(XΠg2) have been determined accurately. The first adiabatic ionization potential (IP) of F2 is determined as IP(F2)=126 585.7±0.5cm−1. To determine the threshold Etipp for ion-pair production of F2, the images of F−(S01) in the velocity mapping conditions have also been recorded at the photon energy of 126 751cm−1. Taking the Stark effect into account, the Etipp is determined as Etipp(F2)=126 045±8cm−1 (15.628±0.001eV). By combing the IP(F2) and the Etipp(F2) determined in this work and together with the reported ionization potential and electronic affinity of the F atom, the bond dissociation energies of F2 and F2+ are determined as D0(F2)=1.606±0.001eV and D0(F2+)...
TL;DR: In this article, the influence of the plasma environments on modified atomic autoionization for isolated atoms/ions by using the complex coordinate rotation method was investigated, which is proved to be a very simple and powerful tool to analyze the position and the width of a resonance.
Abstract: A computational scheme has been developed and used to investigate the influence of the plasma environments on modified atomic autoionization for isolated atoms/ions by using the complex coordinate rotation method which is proved to be a very simple and powerful tool to analyze the position and the width of a resonance. The Debye screening potential is employed to describe the effects of the plasma environments. Stark shifts and widths on the ground state of hydrogen are reported for field strength up to F=0.12a.u. Slater-type basis wave functions are used to describe the system and angular-momentum states up to L=11 are included when the external electric field is turned on. Converged results are obtained by using different maximum angular-momentum states. The modified autoionization for various Debye lengths ranging from infinite to a small value of 0.86 are reported. It has been observed that for a given temperature and under the influence of a given external electric field, the resonance energy and the...