Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPhotoionization Suppression by Continuum Coherence: Experiment and Theory
75
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present experimental and theoretical results of a detailed study of laser-induced continuum structures (LICS) in the photoionization continuum of helium out of the metastable state 2s $^1S_0$. The continuum dressing with a 1064 nm laser, couples the same region of the continuum to the {4s $^1S_0$} state. The experimental data, presented for a range of intensities, show pronounced ionization suppression (by as much as 70% with respect to the far-from-resonance value) as well as enhancement, in a Beutler-Fano resonance profile. This ionization suppression is a clear indication of population trapping mediated by coupling to a contiuum. We present experimental results demonstrating the effect of pulse delay upon the LICS, and for the behavior of LICS for both weak and strong probe pulses. Simulations based upon numerical solution of the Schr{o}dinger equation model the experimental results. The atomic parameters (Rabi frequencies and Stark shifts) are calculated using a simple model-potential method for the computation of the needed wavefunctions. The simulations of the LICS profiles are in excellent agreement with experiment. We also present an analytic formulation of pulsed LICS. We show that in the case of a probe pulse shorter than the dressing one the LICS profile is the convolution of the power spectra of the probe pulse with the usual Fano profile of stationary LICS. We discuss some consequences of deviation from steady-state theory.
rate research
Read More
Photoionization of Kr$^+$ ions was studied in the energy range from 23.3 eV to 39.0 eV at a photon energy resolution of 7.5 meV. Absolute measurements were performed by merging beams of Kr$^+$ ions and of monochromatized synchrotron undulator radiation. Photoionization (PI) of this Br-like ion is characterized by multiple Rydberg series of autoionizing resonances superimposed on a direct photoionization continuum. Resonance features observed in the experimental spectra are spectroscopically assigned and their energies and quantum defects tabulated. The high-resolution cross-section measurements are benchmarked against state-of-the-art theoretical cross-section calculations from the Dirac-Coulomb R-matrix method.
We describe a method for the calculation of photoionization cross-sections using square-integrable amplitudes obtained from the diagonalization of finite-basis set representations of the electronic Hamiltonian. Three examples are considered: a model example in which the final state is a free particle, the hydrogen atom and neutral atomic sodium. The method exploits the Whittaker-Shannon-Kotelnikov sampling theorem, which is widely used in digital signal sampling and reconstruction. The approach reproduces known data with very good accuracy and converges to the exact solution with increase of the basis set size.
The resource theory of coherence studies the operational value of superpositions in quantum technologies. A key question in this theory concerns the efficiency of manipulation and inter-conversion of the resource. Here we solve this question completely for qubit states by determining the optimal probabilities for mixed state
Measurements of the single photoionization cross section of Cu-like Zn$^+$ ions are reported in the energy (wavelength) range 17.5 eV (709 AA) to 90 eV (138 AA). The measurements on this {it trans}-Fe element were performed at the Advanced Light Source synchrotron radiation facility in Berkeley, California at a photon energy resolution of 17 meV using the photon-ion merged-beams end-station. Below 30 eV the spectrum is dominated by excitation autoionizing resonance states. The experimental results are compared with large-scale photoionization cross-section calculations performed using a Dirac-Coulomb $R$-matrix approximation. Comparison are made with previous experimental studies, resonance states are identified and contributions from metastable states of Zn$^+$ determined.
Photoionization cross section $sigma_{nkappa}$, asymmetry parameter $beta_{nkappa}$, and polarization parameters $xi_{nkappa}$, $eta_{nkappa}$, $zeta_{nkappa}$ of Xe and Rn are calculated in the fully relativistic formalism. To deal with the relativistic and correlation effects, we adopt the relativistic random-phase theory with channel couplings among different subshells. Energy ranges for giant emph{d}-resonance regions are especially considered.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
