Search results for "Stark effect"
showing 10 items of 67 documents
Experimental Stark-broadening studies of the NI multiplet $\mathsf{(^{1}D) 3s^{2}D - (^{1}D)3p^{2}P^{o}}$ at 7904.5 �
2004
Experimental Stark-broadening studies of the NI multiplet $(^{1}{\rm D})3s$ $^{2}{\rm D} - (^{1}{\rm D})3p$ $^{2}{\rm P}^{\rm o}$ are reported. Line shape measurements were performed using a wall-stabilized arc operated at atmospheric pressure in helium with small amounts of nitrogen and hydrogen. The radiation of the plasma emitted from nearly homogeneous plasma layers in end-on direction was measured using a grating spectrometer equipped with a charge-coupled device (CCD) detector. The arc current was varied from 35 to 50 A in order to obtain different plasma conditions (electron densities and temperatures). The so-called j(x) profiles of Griem, convoluted with the corresponding Doppler a…
AC-Stark shift and photoionization of Rydberg atoms in an optical dipole trap
2010
We have measured the AC-Stark shift of the $14D_{5/2}$ Rydberg state of rubidium 87 in an optical dipole trap formed by a focussed CO$_2$-laser. We find good quantitative agreement with the model of a free electron experiencing a ponderomotive potential in the light field. In order to reproduce the observed spectra we take into account the broadening of the Rydberg state due to photoionization. The extracted cross-section is compatible with previous measurements on neighboring Rydberg states.
Alignment-orientation transition at optical excitation of molecules in magnetic field
1995
Abstract Angular momentum alignment-orientation transition is analyzed for the ground state of diatomic or linear molecules subjected to the dynamic Stark effect. Analytical expressions are derived for the orientation value. It is shown that, first, orientation of angular momenta resulting from the action of the dynamic Stark effect is a nonlinear process which depends quadratically on the intensity of the irradiating light; second, it is a quantum effect and disappears for the states with large angular momenta; and, third, it occurs only in the presence of an external magnetic field.
SHIFT AND WIDTH OF HeII LINES
1998
Abstract Based on a quantum statistical many-particle theory, the shift and the width of some He II lines have been evaluated. Ion dynamics have been treated within the model microfield method. Furthermore, fine structure splitting has been taken into account in order to check whether this effect is the cause for the existing large discrepancies between theoretical and experimental line widths. Besides the electronic contributions to the line shift, the shift due to the inhomogeneities of the ionic microfield as well as that due to the quadratic Stark effect has been included.
A note on Δn ≠ 0 Stark transitions in hydrogenlike atoms
1992
In a gaseous helium or hydrogen target slow muons or antiprotons are captured into orbits with a high principal quantum number (n = 15 to 50) to form (μ− α)+ ions, (pα)+ ions, or (pp) atoms respectively. In the subsequent deexcitation process Stark mixing of the intermediary states plays an important role. The successful Mainz Cascade Model assumed Δn = 0 for the Stark transitions, although formally no such selection rule exists. This note examines the reasons why Δn ≠ 0 Stark transitions play only a negligible role in the deexcitation cascade.
Local Sensing with the Multi-Level AC Stark Effect
2018
Analyzing weak microwave signals in the GHz regime is a challenging task if the signal level is very low and the photon energy widely undefined. A superconducting qubit can detect signals in the low photon regime, but due to its discrete level structure, it is only sensitive to photons of certain energies. With a multi-level quantum system (qudit) in contrast, the unknown signal frequency and amplitude can be deduced from the higher level AC Stark shift. The measurement accuracy is given by the signal amplitude, its detuning from the discrete qudit energy level structure and the anharmonicity. We demonstrate an energy sensitivity in the order of $10^{-3}$ with a measurement range of more th…
Pulse-driven near-resonant quantum adiabatic dynamics: lifting of quasi-degeneracy
2004
We study the quantum dynamics of a two-level system driven by a pulse that starts near-resonant for small amplitudes, yielding nonadiabatic evolution, and induces an adiabatic evolution for larger amplitudes. This problem is analyzed in terms of lifting of degeneracy for rising amplitudes. It is solved exactly for the case of linear and exponential rising. Approximate solutions are given in the case of power law rising. This allows us to determine approximative formulas for the lineshape of resonant excitation by various forms of pulses such as truncated trig-pulses. We also analyze and explain the various superpositions of states that can be obtained by the Half Stark Chirped Rapid Adiabat…
Computer simulations of hydrogen spectral line shapes in dense plasmas
2002
A new formalism has been elaborated for calculations of hydrogen line profiles emitted by dense plasmas. The main equation of this formalism has a similar form to a set of close-coupled, time-dependent partial differential equations. Calculated line shapes are broadened, shifted and asymmetrical. The formalism yields both shifts and widths of a line calculated within the same theoretical approach. A new basis of the appropriate subspace of the Hilbert space has been built. This basis gives an accurate description of the quadratic Stark effect, and the interaction of the emitter with field gradients. The computer simulation has been used to determine the emitter perturbations by electrons an…
AC Stark shift of the ground state of atomic hydrogen
2004
An analytical expression for the second-order AC Stark shift of the ground state of atomic hydrogen is derived, which is convergent for negative as well as for positive energies of intermediate states except for the resonances. To clarify the applicability of the second-order perturbation theory, we compared results with those which are obtained by us and other authors using nonperturbative methods. It appears that values obtained for the AC Stark shift using our simple formula agree on average with Floquet-method calculations up to the field strength F=0.12 (a.u.), which corresponds to I=1015 W/cm2.
Double modulation sideband spectroscopy: μ0, μ24, and μ44 of 28SiH4
1992
Abstract The linear Stark effect within the ν 2 ν 4 dyad of the main isotopomer of silane, 28 SiH 4 , has been investigated by applying the saturation technique as well as IR-IR double resonance. From 35 transitions, two vibration-induced dipole moment parameters and the centrifugal distortion moment have been determined as μ 0 = 1.357(12) × 10 −5 D, μ 24 = 2.391(31) × 10 −2 D, and μ 44 = −1.261(17) × 10 −2 D employing the Stark coefficients calculated by the procedure of Loete.