Neon Levels Research Articles

Near-threshold electron impact excitation of ultraviolet-emitting levels of neon, argon, krypton and xenon atoms

The excitation by electron impact of levels of neon, argon, krypton and xenon atoms that decay by emission of ultraviolet light has been studied as a function of incident energy up to a few eV above the energies of the lowest excited levels. The width (FWHM) of the energy spread of the incident beam was typically less than 30 meV. A crossed-beam interaction region was used and UV photons emitted approximately normally to the electron and gas beam directions were detected by a channel electron multiplier. Precautions were taken to avoid detection of scattered electrons and metastable atoms by the photon detector. The onset positions of the lowest excited levels were used in calibrating the incident energy scales. The energies of resonance structures in the excitation functions could therefore be obtained, and are compared with the results of previous experiments.

Autoionising neon levels excited in 5-10 keV collisions with lithium and sodium

Electron spectra from 5-10 keV Li+-Ne, Li-Ne, Na+-Ne and Na-Ne collisions have been measured. The Wigner spin-conservation rule causes marked differences between the spectra from neutral and ionic systems. Fifteen lines arising from doubly excited neon levels have been observed. The experimentally determined level energies are found to be in good agreement with recent calculations by Sichel and Langlois (1977).

Formation and decay kinetics of the 2p levels of neon, argon, krypton, and xenon produced by electron-beam pulses

Observations of the kinetics of light emission show that the 2p levels of the rare gases Ne, Ar, Kr, and Xe are produced by three different processes: (1) direct excitation by the electron beam; (2) degradation of higher energy levels; (3) ion recombination. The time dependences of the visible and near-IR emission spectra observed from these gases reveal that process 3 produces a significantly different distribution of 2p levels than does the combination of processes 1 and 2.

Transition probabilities of neon spectral lines at 352 nm, 363 nm and 345 nm

The method of transparent plasma was applied to obtain probabilities for optical transitions between the 4p' [ 1 2 ] 0, 4p [ 1 2 ] 0 and 3s neon levels.

Determination of the relaxation constants of a common level in resonance interaction of opposite waves with a three-level system

An analysis is made of the method for measuring the relaxation constants of a common level in resonance interaction of two opposite traveling waves with a three-level system, based on the modulation of the polarization of one of the waves. The results for the 3s2 level of neon, obtained experimentally for the 3s2–3p2 and 3s2–3p4 transitions, were in agreement with the values obtained earlier by other methods.

High resolution Zeeman spectroscopy on the neon levels 2s 2 and 2p 4 by mode crossing at high magnetic fields

Mode crossing signals in laser intensity occur if the Zeeman splitting of one laser level equals the frequency separation between two laser modes. This kind of experiment using two optical frequencies for double resonance yields high resolution in Zeeman spectroscopy and allows very accurate determination ofg J -values. Mode crossing dips of the 0.633μ, 1.152μ and 1.523μ transitions of the He-Ne-laser in an axial magnetic field were measured by tuning the field strength up to 0.17 Tesla. At this field strength the Zeeman splitting of the Dopplerbroadenedσ-lines corresponds to approximately 6 Gcps. The frequency separation between resonant modes was controlled by means of a scanning high resolution Fabry-Perot. The experimental results for theg J -values areg J =1.2211±0.002 for the Ne 2s2 level andg J =1.3008±0.002 for the Ne 2p4 level. A pressure inducedg J -shift of aboutΔg J /(g J ×pHe)=−1.6×10−3/Torr for the 2p4 level has been observed. The influence of helium collisions disturbing the Zeeman splitting of the 2p4 state is discussed.

Resonance structure in elastic electron scattering from helium, neon and argon

High energy-resolution spectra of electrons scattered elastically from helium, neon and argon atoms have been obtained as functions of scattering angle and of incident electron energy. In addition to the well known levels of the lowest configurations of the temporary negative ions (resonances), the authors observe structures at energies close to those of the (core)np5(n+1)s levels of neon and argon. These structures are attributed to resonances having configurations (core)np5((n+1)s(n+1)p3P). By calibration against features occurring at known energies in the elastic scattering spectra and also metastable excitation spectra they determine accurately the energies of the observed resonances.

New g J-values and pressure induced g J-shift of the neon 2p 4 level measured by optical-optical double resonance

Mode crossing experiments yield high resolution in Zeeman spectroscopy of higher excited states. The g J-values of the neon levels 2p 4 and 2s 2 have been measured by mode crossing on 0.633 microm, 1.152 microm and 1.523 microm HeNe-laser tuning the axial magnetic field up to 0.17 T. A slight pressure induced g J-shift of the 2p 4 level is observed.

Autoionizing levels in neon excited by low-energy heavy-ion impact

Energy spectra of electrons ejected from autoionizing states in neon, excited in 0.5-15 keV Ne+-He, He+-Ne, Li+-Ne, Na+-Ne and Mg+-Ne collisions have been measured. Due to quasi-molecular effects spectral features from the autoionizing configurations 1s22s22p4 nln'l' are preferentially excited. 13 lines in the region 20-30 eV are reported. Their assignments to specific levels are discussed and the need for theoretical calculations is pointed out.

Destruction par chocs électroniques des atomes métastables et pseudo-métastables de néon dans une colonne positive

2014 The population frequency response of the 1s3, 1s4, 1s5 levels of Neon to a weak modulation of the discharge current has been studied in the positive column of a glow discharge. The following values are found for the deexcitation coefficients by electron impact : 03B2(1s3) = 03B2(1s5) = (10.4 ± 2) 10-7 cm3.s-1 03B2(1s4) = (27 ± 4) 10-7 cm3.s-1. LE JOURNAL DE PHYSIQUE LETTRES TOME 38, ler OCTOBRE 1977, Classification Physics Abstracts 34. 80D ,

Calculation of doubly excited energy levels of rare-gas atoms by a frozen-core superposition-of-configurations method. I. Description of method and comparison with experiment for optically allowed levels of Ne

A method is described for the calculation of doubly excited energy levels of rare-gas atoms. The calculation makes use of frozen-core Hartree-Fock orbitals, optimized orthogonalized Slater-type functions to describe excited orbitals and virtual orbitals appearing in a superposition of configurations, and an empirical correction for core correlation. The method is found to be accurate to 0.1 eV for the 1s22s22p4(3P,1D,1S)3snp(1Po) levels of neon (n=3,4), as well as the singly excited 1s22s2p6np(1Po) levels (n=3-6). Modifications are described for the case of two or more states of the same symmetry, formed from the same core state and the same excited orbitals (e.g. 1s22s22p4(3P)3s(2,4P)3p(3Po)).

Resonant multiphoton ionization of neon. Experimental determination of the polarizability of the3p′[12]1level

Multiphoton ionization of neon in the case of a 16-photon resonance with the $3{p}^{\ensuremath{'}}{[\frac{1}{2}]}_{1}$ intermediate level is studied using a neodymium-glass laser. Experiments show that when the electric field $E$ ranges from 2.2 \ifmmode\times\else\texttimes\fi{} ${10}^{7}$ to 3.5 \ifmmode\times\else\texttimes\fi{} ${10}^{7}$ V/cm, the number of collected charges takes a maximum value at 2.9 \ifmmode\times\else\texttimes\fi{} ${10}^{7}$ V/cm. A theoretical study on the basis of the formalisms due to Keldysh and Zon etal predicts that, when an intermediate resonant level is considered, this maximum can be observed by the use of a laser beam of sufficiently large spectral width. This is the case in our experiment. The number of ionization events decreases when the resonance is destroyed, i.e., when the Stark shift of the level becomes larger than the spectral width of the laser, which, at 16 photons, is of the order of 100 \AA{}. Good agreement between experiment and theory allows us to determine the polarizability of the resonant $3{p}^{\ensuremath{'}}{[\frac{1}{2}]}_{1}$ level of neon which is found to be 21.8 ${\mathrm{\AA{}}}^{3}$. We have also determined an experimental cross section of multiphoton ionization of neon at $\ensuremath{\lambda}=1.06$ \ensuremath{\mu}m.

Level crossing method compared with recent achievements in high-resolution laser spectroscopy

The level crossing method is illustrated by the determination of the Stark constant of the 62P3/2 term of rubidium, lifetimes and depolarizing-collision cross sections of the 53D3 and 43F2,3,4 levels of cadmium, lifetimes of some high neon levels, and the hyperfine structure of the D lines of sodium. The results obtained by the level crossing method are compared with those deduced by laser spectroscopy (two-photon excitation, saturated absorption, laser excitation of an atomic beam).

Lifetime of the1s2(P11)and1s4(P13)levels of neon by the cascade Hanle effect

The theory of the cascade level-crossing effect as formulated by Happer is evaluated for zero-nuclear-spin atomic systems and extended to include the case of a polarized initial state. We have used this theory to interpret our cascade-Hanle-effect results (zero-field level crossings) to obtain the lifetime of the two resonance levels, $1{s}_{2}(^{1}P_{1})$ and $1{s}_{4}(^{3}P_{1})$, of the $2{p}^{5}3s$ configuration of neon. The resonance lines 744 \AA{} ($1{s}_{4}\ensuremath{-}^{1}S_{0}$) and 736 \AA{} ($1{s}_{2}\ensuremath{-}^{1}S_{0}$) are produced in the cascade to the ground $^{1}S_{0}$ state when a beam of metastable $1{s}_{3}(^{3}P_{0})$ and $1{s}_{5}(^{3}P_{2})$ neon atoms is excited by selected lines of the $2{p}^{5}3s\ensuremath{-}2{p}^{5}3p$ transition array. Our results are $\ensuremath{\tau}(1{s}_{2})=1.65\ifmmode\pm\else\textpm\fi{}0.16$ nsec and $\ensuremath{\tau}(1{s}_{4})=20.5\ifmmode\pm\else\textpm\fi{}1.5$ nsec.

Population transfer on Ne metastable atoms

We describe an experiment allowing transfer measurement on metastable levels of neon of the perturbation induced by the 6328 Å laser light on the upper levels. First results are given.

Born and four-state calculations for the excitation of the (2p)43s and (2p)53p levels of neon by proton impact

For the singlet levels of (2p)53s and (2p)53p of the Ne atom wavefunctions of Hartree-Fock type are constructed. The Born calculations yield the new Bethe parameter bn=0.050 for the (2p)53p states. A four-state impact parameter calculation is carried out including the states 1S(2p)6, 1S(2p)53p and 1P(2p)53s (M=0,1). With this relatively simple model all known experimental data for the excitation of (2p)53s and (2p)53p by proton impact can be explained satisfactorily.

On the Populations of Neon Levels in the Low Temperature Plasma of a Hollow Cathode Discharge

Abstract Atomic levels population measurements constitute an essential contribution to various aspects of plasma research: balance and cross-section of inelastic processes, admixtures effects on level excitation mechanism, purposeful optimisation of plasma parameters etc. Atomic level populations in the negative glow of a hollow cathode discharge are of utmost interest in view of the peculiarities of the spectral source: a rich spectrum consisting of gas lines, lines of the cathode material and also lines of the substances introduced in the discharge; intensive atomic and ionic lines of high excitation potentials; small spectral linewidth, convenient for analytical purposes.

Absolute cross sections for the excitation of the 1s 2- and 1s 4-levels of neon and argon by proton impact (100 keV to 1150 keV)

The excitation of the 1s2 and 1s4 levels in neon and argon has been studied by proton impact in the energy range of 100 to 1150 keV. The results are compared with other experimental and theoretical data.

Structure in near threshold electron excitation of argon and neon

Excitation of the first excited levels of argon and neon have been observed around threshold. The experiment was carried out in a crossed-beam arrangement. An electron gun with energy width of less than 100 meV was used. The excitation was observed at 90 degrees . No correction for polarization has been applied. Resonance structure has been found. The structure is compared with structure found in transmission experiments and total cross section measurements for metastable excitation.

Born cross sections for the excitation of the lowest resonance level of neon using elaborate CI wavefunctions

Born cross sections are calculated for the excitation of the 1P1(2p) 53s level of Ne by electron and proton impact using Hartree-Fock wavefunctions and two sets of different CI wavefunctions. The optical oscillator strength obtained with the largest CI wavefunctions is 0.149.