Hyperfine Structure of1snpP3Terms ofLi6,7ii (original) (raw)
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Journal of Physics B: Atomic, Molecular and Optical Physics
We use the Baranger model to compute collisional broadening and shift rates for the D 1 and D 2 spectral lines of M + Ng, where M = K, Rb, Cs and Ng = He, Ne, Ar. Scattering matrix elements are calculated using the channel packet method, and non-adiabatic wavepacket dynamics are determined using the split-operator method together with a unitary transformation between adiabatic and diabatic representations. Scattering phase shift differences are weighted thermally and are integrated over temperatures ranging from 100 K to 800 K. We find that predicted broadening rates compare well with experiment, but shift rates are predicted poorly by this model because they are extremely sensitive to the near-asymptotic behavior of the potential energy surfaces.
The Journal of Chemical Physics, 2006
The absorption of light during atomic collisions is treated by coupling electronic excitations, treated quantum mechanically, to the motion of the nuclei described within a short de Broglie wavelength approximation, using a density matrix approach. The time-dependent electric dipole of the system provides the intensity of light absorption in a treatment valid for transient phenomena, and the Fourier transform of time-dependent intensities gives absorption spectra that are very sensitive to details of the interaction potentials of excited diatomic states. We consider several sets of atomic expansion functions and atomic pseudopotentials, and introduce new parametrizations to provide light absorption spectra in good agreement with experimentally measured and ab initio calculated spectra. To this end, we describe the electronic excitation of the valence electron of excited alkali atoms in collisions with noble gas atoms with a procedure that combines l-dependent atomic pseudopotentials...
We report a precise measurement of the hyperfine interval in the 2P 1/2 state of 7 Li. The transition from the ground state (D 1 line) is accessed using a diode laser and the technique of saturated-absorption spectroscopy in hot Li vapor. The interval is measured by locking an acousto-optic modulator to the frequency difference between the two hyperfine peaks. The measured interval of 92.040(6) MHz is consistent with an earlier measurement reported by us using an atomic-beam spectrometer [Das and Natarajan, J. Phys. B 41, 035001 (2008)]. The interval yields the magnetic dipole constant in the P 1/2 state as A = 46.047(3), which is discrepant from theoretical calculations by >80 kHz.
The Journal of Chemical Physics, 1989
To gain insight into the mechanism of Na(3p)2P3/2→2P1/2 fine-structure transitions induced by collision with He, we monitor the expectation values of the orbital- and spin-angular momentum vectors, l and s, as a function of time along the trajectory, using a semiclassical formalism. In a typical collision, 〈s〉 remains nearly space-fixed while 〈l〉 precesses about the rotating internuclear axis. Thus, in the interaction region, the projection of 〈l〉 onto the internuclear axis, 〈λ〉, remains nearly constant, and the molecular alignment of the orbital is preserved. We show how equations of motion for the classical analogues of these expectation values agree qualitatively with the quantum equations of motion. A qualitative comparison is also made with the Cs–He system for which the spin–orbit coupling is much stronger. We calculate cross sections for Na(2P3/2)+He→Na(2P1/2)+He as a function of the alignment of the excitation laser polarization with respect to the asymptotic relative veloci...
Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV
Nuclear Physics A, 2006
Quasi-elastic scattering of 6 He at E lab =27 MeV from 197 Au has been measured in the angular range of 6 • − 72 • in the laboratory system employing LEDA and LAMP detection systems. These data, along previously analysed data of 6 He + 208 Pb at the same energy, are analysed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6 He induced reactions.
Journal de Physique, 1984
2014 Les auteurs ont calculé par la technique Hartree-Fock les contributions du spectre discret aux paramètres décrivant les effets croisés du second ordre des interactions électrostatiques et hyperfines (paramètres de Bauche-Amoult) pour les configurations 3dN 4s et 3dN-1 4s2 des éléments du groupe du fer. Ils proposent une méthode d'extrapolation pour estimer les contributions totales des états liés. Ils montrent que, dans le cas de la configuration 3dN 4s, les contributions les plus importantes proviennent des excitations 4s ~ ns, 3d ~ nd, ns ~ 3d et ns ~ 4s; tandis que, dans le cas de la configuration 3dN-1 4s2, elles proviennent des excitations 3d ~ nd et ns ~ 3d. Les contributions de 3d ~ ng et de 3d ~ ns sont toujours très petites. Abstract. 2014 Hartree-Fock values of discrete spectrum contributions to the parameters describing crossed secondorder effects of electrostatic and hyperfine interactions (Bauche-Amould parameters) have been calculated for 3dN 4s and 3dN-1 4s2 configurations of the first row transition metal atoms. An extrapolation procedure is proposed to estimate the total bound state contributions. It is shown that in the case of 3dN 4s configuration the most important are the 4s ~ ns, 3d ~ nd, ns ~ 3d and ns ~ 4s excitations, while, in the case of 3dN-1 4s2, they are the 3d ~ nd and ns ~ 3d ones. The contributions from 3d ~ ng and 3d ~ ns excitations are always very small.
Hyperfine structure and lifetimes of some excited levels inCs+
Physical review, 1980
Hyperfine-structure (hfs) measurements of the 592-nm Sd[7/2]"'-6p[5/2]" the 612-nm Sd [3/2]i-6p[5/2]" and the 581-nm Sd[3/2];-6p[3/2]& transitions in Csri are performed with the beam-laser technique. The hyperfine coupling constants A and B are evaluated from the experimental data. A comparison with semiempirical calculations of the hfs constants is made. Radiative lifetimes of the levels 6p[5/2]"6p [3/2]i, and 6p[3/2], are measured with the cascade-free beam-laser technique. The measured lifetimes are compared with lifetimes obtained from semiempirical calculations using the Coulomb approximation.
Physical Review A, 1997
To enhance the current understanding of mechanisms contributing to magnetic hyperfine interactions in excited states of atomic systems, in particular, alkali-metal atom systems, the hyperfine fields in the excited 5 2 S 1/2-8 2 S 1/2 states of potassium and 8 2 S 1/2-12 2 S 1/2 states of francium atoms have been studied using the relativistic linked-cluster many-body perturbation procedure. The net theoretical values of the hyperfine fields for the excited states studied are in excellent agreement with available experimental data for both atoms. There is a significant decrease in importance of the correlation contribution in going from the ground state to the excited states, the correlation contributions as ratios of the direct contribution decreasing rapidly as one moves to the higher excited states. However, the contribution from the exchange core polarization ͑ECP͒ effect is nearly a constant fraction of the direct effect for all the excited states considered. Physical explanations are offered for the observed trends in the contributions from the different mechanisms. A comparison is made of the different contributing effects to the hyperfine fields in potassium and francium to those in the related system, rubidium, studied earlier. Extrapolating from our results to the highly excited states of alkali-metal atoms, referred to as the Rydberg states, it is concluded that in addition to the direct contribution from the excited valence electron to the hyperfine fields, a significant contribution is expected from the ECP effect arising from the influence of exchange interactions between electrons in the valence and core states. ͓S1050-2947͑97͒07907-9͔