Metastable 3P2 State Research Articles

Double Differential Cross-sections for Ionization of Metastable 2P-state Hydrogen Atoms by Electrons at Intermediate Energies with Exchange Effects

Double differential cross sections were obtained from the triple differential cross sections. The present calculations are compared with the hydrogenic ground-state experimental data, theoretical results, and DDCS first Born results. Discrepancies have been found between the present results and those measurements and theoretical results and also qualitative agreement with those of compared theories. The exchange effect results give an enormous prospect for experimental outcomes in the field of ionization problems. We are expecting that the present study makes more significant contribution to the study of atomic scattering problems using the multiple scattering theories. In the future calculations, other kinematic conditions or other atomic species will also be interesting and significant.

Coherent dynamics in a five-level atomic system

The coherent control of multi-partite quantum systems presents one of the central prerequisites in state-of-the-art quantum information processing. With the added benefit of inherent high-fidelity detection capability, atomic quantum systems in high-energy internal states, such as metastable noble gas atoms, promote themselves as ideal candidates for advancing quantum science in fundamental aspects and technological applications. Using laser-cooled neon atoms in the metastable 3P2 state of state 1s 22s 22p 53s (LS-coupling notation) (Racah notation: 2 P 3/23s[3/2]2) with five m J -sublevels, experimental methods for the preparation of all Zeeman sublevels |m J ⟩ = |+2⟩, |+1⟩, |0⟩, |−1⟩, |−2⟩ as well as the coherent control of superposition states in the five-level system |+2⟩, …, |−2⟩, in the three-level system |+2⟩, |+1⟩, |0⟩, and in the two-level system |+2⟩, |+1⟩ are presented. The methods are based on optimized radio frequency and laser pulse sequences. The state evolution is described with a simple, semiclassical model. The coherence properties of the prepared states are studied using Ramsey and spin echo measurements.

Ultracold collisions in the Yb-Li mixture system

We report our experimental results on the collisional physics between non-S-state atoms (ytterbium (Yb), effectively a two-electron system, in the metastable 3P2 state) and S-state atoms (lithium (Li), an alkali metal, in the ground state). At low magnetic fields, by measuring inelastic interspecies collisional losses in the double quantum degenerate mixture we reveal the strong dependence of the inelastic losses on the internal spin states of both species and suppressed losses in stretched state configurations. Increasing the magnetic field up to 800 G we further investigate the magnetic field dependence of the collisional interactions. There, smoothly increasing inelastic losses are observed towards higher fields. The combined knowledge of both the magnetic field and the spin state dependence of the collisional losses of this prototypical mixture system of non-S-state and S-state atoms provides a significant step forward towards controllable impurity physics realized in the Yb-Li ultracold system.

Quenching rate of N(2P) atoms in a nitrogen afterglow at atmospheric pressure

We present the results of an experimental determination of the quenching rate of the metastable 2P state of atomic nitrogen by nitrogen molecules. 2D density profiles of N(2P) and N(4S) atoms were measured by absolute optical emission spectroscopy inside a tube placed downstream of an atmospheric pressure pulsed discharge in nitrogen. The results are analyzed by means of a detailed kinetic model taking into account the major processes of production and depletion of N(2P). The quenching rate constant of N(2P) by N2 molecules determined with this method at atmospheric pressure and T = 300 K is k = (3 ± 1) × 10−17 cm3 s−1.

Triple differential cross-sections for the ionization of metastable 2P-state hydrogen atoms by electrons with exchange effects

In this paper, triple differential cross-sections for the ionization of metastable 2P-state hydrogen atoms by 250 eV electron energy with exchange effects for various kinematic conditions are calculated. Multiple scattering theory proposed by Das and Seal in Phys. Rev. A 47, 2978 (1993) is utilized here. The computational results provide significant peak features that show good qualitative agreement with the hydrogenic ground-state experimental data and theoretical results and the present first Born results. In addition, physical origin of the peaks of the cross-section curves is investigated.

Energy Spectrum of Ejected Electrons of H(2P) Ionization by Electrons in Coplanar Asymmetric Geometry

We have investigated the energy spectrum of ejected electrons of hydrogen atoms ionization from metastable 2P state by electrons in coplanar asymmetric geometry. A multiple scattering theory of Das and Seal is applied. The present results show very interesting binary peak features. As well as a significant qualitative agreement with hydrogenic ground state results is obtained. New theoretical results and experimental verification for such treatment in hydrogenic metastable states by electrons will be interesting.

Electron impact ionization of metastable 2P-state hydrogen atoms in the coplanar geometry

Triple differential cross sections (TDCS) for the ionization of metastable 2P-state hydrogen atoms by electrons are calculated for various kinematic conditions in the asymmetric coplanar geometry. In this calculation, the final state is described by a multiple-scattering theory for ionization of hydrogen atoms by electrons. Results show qualitative agreement with the available experimental data and those of other theoretical computational results for ionization of hydrogen atoms from ground state, and our first Born results. There is no available other theoretical results and experimental data for ionization of hydrogen atoms from the 2P state. The present study offers a wide scope for the experimental study for ionization of hydrogen atoms from the metastable 2P state.

Ultracold Heteronuclear Mixture of Ground and Excited State Atoms

We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in an excited metastable (3P2) state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K2'<3×10(-12) cm3/s for the 3P2 mJ=-1 substate. We calculate the dynamic polarizabilities of the Yb(3P2) magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064 nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.

Ionization of Metastable 2P-State Hydrogen Atoms by Electron Impact for Coplanar Asymmetric Geometry

The triple differential cross-sections of First Born approximation have been calculated for ionization of metastable 2P-state hydrogen atoms by electron impact in the asymmetric coplanar geometry. In this study a multiple scattering theory of ionization of hydrogen atoms is used. The latest results of the present method are compared with other calculations. It will be added for new experimental study of ionization of hydrogen atoms in their metastable states.

Magneto-optical trapping of bosonic and fermionic neon isotopes and their mixtures: isotope shift of the 3P2 ↔ 3D3 transition and hyperfine constants of the 3D3 state of 21Ne

We have magneto-optically trapped all three stable neon isotopes, including the rare 21Ne, and all two-isotope combinations. The atoms are prepared in the metastable 3P2 state and manipulated via laser interaction on the 3P2 ↔ 3D3 transition at 640.2 nm. These cold (T ≈ 1 mK) and environmentally decoupled atom samples present ideal objects for precision measurements and the investigation of interactions between cold and ultracold metastable atoms. In this work, we present accurate measurements of the isotope shift of the 3P2 ↔ 3D3 transition and the hyperfine interaction constants of the 3D3 state of 21Ne. The determined isotope shifts are (1625.9 ± 0.15) MHz for 20Ne ↔ 22Ne, (855.7 ± 1.0) MHz for 20Ne ↔ 21Ne, and (770.3 ± 1.0) MHz for 21Ne ↔ 22Ne. The obtained magnetic dipole and electric quadrupole hyperfine interaction constants are A(3D3) = (−142.4 ± 0.2) MHz and B(3D3) = (−107.7 ± 1.1) MHz, respectively. All measurements give a reduction of uncertainty by about one order of magnitude over previous measurements.

Collisional Properties of Cold Spin-Polarized Metastable Neon Atoms

We measure the rates of elastic and inelastic two-body collisions of cold spin-polarized neon atoms in the metastable 3P2 state for 20Ne and 22Ne in a magnetic trap. From particle loss, we determine the loss parameter of inelastic collisions beta=6.5(18) x 10(-12) cm(3) s(-1) for 20Ne and beta=1.2(3) x 10(-11) cm(3) s(-1) for 22Ne. These losses are caused by ionizing (i.e., Penning) collisions and occur less frequently than for unpolarized atoms. This proves the suppression of Penning ionization due to spin polarization. From cross-dimensional relaxation measurements, we obtain elastic scattering lengths of a=-180(40)a(0) for 20Ne and a = +150(+80)(-50)a(0) for 22Ne, where a(0)=0.0529 nm.

Precision measurement of the metastable3P2lifetime of neon

The lifetime of the metastable 3P2 state of neon has been determined to 14.70(13) s (decay rate 0.06801(62) 1/s) by measuring the decay in fluorescence of an ensemble of Ne-20 atoms trapped in a magneto-optical trap (MOT). Due to low background gas pressure p < 5 10^-11 mbar and low relative excitation to the 3D3 state (0.5% excitation probability) operation only small corrections have to be included in the lifetime extrapolation. Together with a careful analysis of residual loss mechanisms in the MOT a lifetime determination to high precision is achieved.

Channels of energy transfer to atomic nitrogen in excited argon–nitrogenmixtures

The vacuum ultraviolet (VUV) and ultraviolet (UV) emissions of gaseousmixtures of argon with a small amount of nitrogen were investigated in theafterglow of a pulsed transverse discharge. The time dependences of the intensityof the VUV argon continuum at 126.0 nm, the UV nitrogen molecular band at337.0 nm, and the VUV nitrogen atomic lines at 149.47 and 174.52 nm wereanalysed in the total pressure range 150–600 hPa and the range 0.125–1.5 hPa ofthe admixture concentrations. The results show that all these emissions have acommon source of excitation energy, namely the atomic metastable 3P2state of argon. However, atomic nitrogen also receives energy from theatomic 3P1 state of argon and from the excited Ar2* (1u)molecules.

Potential energy curves and dipole transition moments for electronic states of ArHe and HeNe

Relativistic core-potential calculations have been carried out on the ground and excited Ω states of ArHe and HeNe correlating with the atomic limits Ar*(3p54s, 3P,1P) and Ne*(2p53s, 3P,1P), respectively, and with ground-state He atoms. The potential energy curves of the excited states of ArHe are repulsive. The potential energy curves of the 0−(I), 1(I) and 0+(II)2pσ→3s states of HeNe show a local Rydberg minimum at 2.8 bohr and a barrier at 4.0 bohr, while the other excited state potentials of HeNe are repulsive. For both ArHe and HeNe, large dipole transition moments are calculated connecting the ground state with states dissociating to atomic limits from which radiative transitions to the atomic ground state are allowed. Small but nonzero dipole transition moments are obtained for short internuclear distances for the transitions from the 1(I) state, which correlates with the metastable P23 state of Ar (in ArHe) or Ne (in HeNe). The radiative lifetime of the 1(I) state of HeNe (estimated from the vertical transition at 2.8 bohr) is 18 μs.

Potential energy curves and dipole transition moments to the ground state of the system Ar*(3p54s, 3P, 1P)+Ne

Relativistic core-potential calculations have been carried out on Ω states resulting from the interaction of Ar*(3p54s, 3P, 1P) with ground state Ne atoms. The results yield the correct asymptotic limits for the atomic states of Ar while shallow minima (700–800 cm−1) at large internuclear distances, 7–8 bohr, are obtained for the excited states. Dipole transition moments between pairs of states have been calculated and strong radiative transitions are predicted from excited states to the ground state. The 1(I) state, correlating with the metastable P23 state of Ar is found to have a small dipole transition moment at short and intermediate nuclear distances leading to a radiative lifetime for this state of 8.3 μs.

Excitation of bands of the first negative system of the N 2 + ion in collisions of N+ and O+ ions with N2 molecules

Absolute values of the excitation cross sections of the (0,0) bands [for O+(4 S), O+(2 P)-N2 pairs] and the (0,0), (0,1), (1,2), and (2,3) bands [for N+(3 P)-N2 pairs] of the first negative system of the N 2 + ion have been measured in collisions with nitrogen molecules of nitrogen and oxygen ions in the ground state and in a metastable state in the interval of ion energies 1–10 keV. The process of excitation of the (0,0) band of the first negative system of the N 2 + ion by oxygen ions in the metastable 2 P state is of a quasi-resonant character. The presence in the beam of ions in metastable states was monitored by measuring the excitation efficiency of the (0,0) band λ3914 A of the N 2 + ion in different operating regimes of the highfrequency ion source. For N+ ions in the 3 P ground state, as the collision frequency is decreased the relative vibrational population of the v′=1 and v′=2 levels of the B 2Σ u + state of the N 2 + ion is observed to deviate strongly from the value calculated in the Franck-Condon model.

The heteronuclear excimers ArKr*, ArXe*and KrXe*

If solid layers of condensed Ar or Kr are bombarded with thermal Xe or Kr atoms in the metastable 3P2 state, the mixed rare-gas excimers ArKr*, ArXe* and KrXe* are formed on or within the surface. From the observed vacuum UV emissions between 110 and 190 nm, the following binding energies with respect to dissociation for these heteronuclear excimers can be derived: ArKr* (106+or-20) meV, ArXe* (38+or-3) meV and KrXe* (138+or-50) meV. While in the case of KrXe* the binding energy reported by other authors is confirmed, the existence of ArKr* and ArXe* is unequivocally established for the first time. From the obtained vacuum UV spectra, the potential parameters for the three heaviest rare-gas excimer systems are deduced.

89. Lifetime of the metastable 2P state of the nitrogen atom: J.M. Anderson and J.R. Burrows, Nature, 193 (4818), 3 March 1962, 865–866

89. Lifetime of the metastable 2P state of the nitrogen atom: J.M. Anderson and J.R. Burrows, Nature, 193 (4818), 3 March 1962, 865–866

Lifetime of the metastable 2P state of the nitrogen atom

Lifetime of the metastable 2P state of the nitrogen atom

Life-time of the Metastable 2P State of the Nitrogen Atom

DURING an investigation, which is not yet complete, of the life of the vibrational levels above the ground-state of the nitrogen molecule, measurements were made of the decay of the 2P state of the nitrogen atom at a series of pressures. The decay was found to be exponential for pressures from 0.1 to 5 mm. and in repeated series with the purest nitrogen was found to obey the relation 1/τ=180 p−1 + 230 p2. A straight line within the limits of reading errors was obtained for a plot of p/τ against p3 over this wide range of variables. No such line could be fitted for a plot of p/τ against p2.