Ions In Neon Research Articles

The mobility of N 2+ ions in neon measured by a modified Townsend drift technique

The pulsed Twonsend discharge technique is modified by eliminating the flash-lamp. In the range of reduced field strength from 12 to 30 V cm -torr mobilities for N 2 + ions is neon are found ranging from 9.7 to 6.3 cm 2 V-sec .

Mobility of mass-identified ions in neon and reaction rate coefficient for Ne + + 2Ne → Ne +2 + Ne

The mobilities of mass-identified Ne + and Ne + 2 ions in neon have been measured by the “four-gauze” electrical shutter method at 300°K. The reduced zero-field mobilities of Ne + and Ne + 2 ions, corrected to 273°K, are 4.13± 0.04 and 6.20± 0.07 cm 2V −1sec −1 respectively. The reaction rate coefficient for the termolecular ion-neutral association reaction is (4.6 ± 0.35) × 10 −32 cm 6 sec −1 and in the range from 2 to 10 V cm −1 torr −1 it does not depend on the electric field strength.

On the anomaly in the cross sections for electron loss and capture by multiply charged ions in neon

The electron loss and capture cross sections for multiply charged He, N, Ne and Ar ions at velocities V from 3*108 to 109 cm s-1 in helium, nitrogen, neon and argon have been measured. It has been found that due to a higher average velocity of outer electrons in Ne atoms the dependences of these cross sections on nuclear charge of target atoms at V approximately 109 cm s-1 become nonmonotonic: the values sigma i'i+1 in neon become smaller and sigma i,i-1 greater than in nitrogen and argon.

Formation of metastable helium atoms by electron capture during the passage of fast He+ions through gases

A beam attenuation technique, developed previously in this laboratory, has been used to investigate the formation of metastable helium atoms by electron capture of 10-200 keV He+ ions in hydrogen, helium, neon, argon, krypton and nitrogen. The fractions of metastable atoms formed in both thin and thick targets have been determined and used to obtain separate cross sections for the formation of ground state and metastable atoms. The equilibration of the metastable component of the beam in thick targets has also been described quantitatively in terms of the relevant charge changing collisions.

Afterglow study in neon-helium mixture

A microwave cavity method was used to measure the electron density in the afterglow period of a pulsed dc glow discharge. The measurements were carried out in the mixture neon with 6 × 10−2% of helium for the pressure interval from about 5 to 25 torr.The de-excitation cross section of metastable atoms was found to be 1·09 × 10−19 cm2. It was also found that the late afterglow period is affected only by the ambipolar diffusion of ions and electrons at all measured gas pressures.The value of an effective reduced mobility coefficient was calculated from the measured value of the ambipolar diffusion coefficient and it was found to be 8·37 ± 0·84 cm2V−1 s−1. This value is in a good agreement with the theoretical value calculated according to the Langevin formula for molecular (NeHe)+ ions in neon. It is supposed that these ions strongly affect loss processes of electrons in this mixture during the afterglow period.

Mobilities and Reaction Rates of Neon Ions in Neon

Mobilities and Reaction Rates of Neon Ions in Neon

Note on diffusion and drift of positive ions in neon

Measurements of the drift velocity W and the diffusion coefficient D for selected species of neon ions in neon were made over the range 3 < E/p0 < 45 v cm-1 torr-1. Two species of ion, having zero field mobilities of 4 and 7.5 cm2 sec-1 v-1, were observed. The diffusion coefficient for the slower species increased from an approximately constant value at low values of E/p0 and tended to the form D [is proportional to] (E/p0)1/2 at high values of E/p0. Above a value of E/p0 about 3 v cm-1 torr-1 the energy of these ions was shown to increase with increasing E/p0.

The Mobility of Potassium Ions in Nitrogen and Neon at 294 K

The mobility of potassium ions in nitrogen and neon has been measured by an electrical shutter method of the type developed by Bradbury and Nielsen for measuring electronic drift velocities. The values obtained for the mobility μ0, 2.54 and 7.42 cm2 volt-1 sec-1 for nitrogen and neon respectively, are in good agreement with those listed by Tyndall. The variation of the mobility with E/p0 is shown to be in qualitative agreement with theoretical considerations while the disagreement between the present results and those of Mitchell and Ridler is discussed.

Elastic and Inelastic Scattering of Low-Velocity Ions: He+ in Ne, Ne+ in He, and Ne+ in Ne

Experimental results are presented for collisions in the energy range 4 to 400 electron volts of He+ ions in neon and of Ne+ ions in helium and in neon. Charge exchange was observed only in the case of Ne+ in neon. Empirical potential functions for the interactions are tabulated and discussed. It is concluded that the HeNe+ ion, if formed, would probably separate if subjected to impact at thermal energies.

Mobilities of Mercury Ions in Helium, Neon, and Argon

The mobilities of mercury ions in helium, neon, and argon have been measured at 300\ifmmode^\circ\else\textdegree\fi{}K. The values obtained are ${\ensuremath{\mu}}_{0}=19.6(\mathrm{He}), 5.95 (\mathrm{Ne}), \mathrm{and} 1.84 (\mathrm{A})$ ${\mathrm{cm}}^{2}$/volt-sec. These values are in agreement with extrapolations of the mobility versus mass-number curves obtained for alkali ions in the noble gases by Tyndall and collaborators. The experimental values for ${\mathrm{Hg}}^{+}$ are compared with the Langevin theory in the polarization limit. Good agreement is obtained only for the case of argon.

Scattering of Low-Energy H— Ions in Helium, Neon, and Argon

Elastic and inelastic cross sections have been measured for the scattering of H— ions in helium, neon, and argon gases, at incident ion energies in the range 5 ev to 350 ev. One term interaction potentials of the form V=—K/rn were calculated from the low-energy elastic cross sections. These potentials were: for H— and He, V=—2.90/r3.01 ev for r=1.30 A to 1.90 A; for H— and Ne, V=—4.17/r2.80 ev for r=1.00 A to 1.78 A; and for H— and A, V=—7.82/r3.40 ev for r=1.23 A to 2.12 A. The observed inelastic cross sections are interpreted as cross sections for electron detachment from H—; they show a similar behavior with ion energy W in the three cases, appearing at W between 0 and 5 ev, rising rapidly to W=40 ev, and then rising very slowly to W=350 ev. Evidence was found for positive ion formation in H— collisions with Ne and A atoms at ion energies above 100 ev.

Mobilities of Atomic and Molecular Ions in the Noble Gases

A method is described for measuring the mobilities of ions of near-thermal energy. A pulse of ions is generated in a discharge region and passes through a grid into a drift region where a uniform electric field causes the ions to move to a collector electrode. The mobilities are determined from measurements of the transit time of the ions in crossing the drift space. The experimental mobility values for thermal energy ions moving in their parent gases at 300\ifmmode^\circ\else\textdegree\fi{}K and a gas density of 2.69\ifmmode\times\else\texttimes\fi{}${10}^{19}$ atoms/cc are ${\ensuremath{\mu}}_{0}=10.5$ ${\mathrm{cm}}^{2}$/volt-sec (${\mathrm{He}}^{+}$), 20.3 (${\mathrm{He}}_{2}^{+}$), 4.0 (${\mathrm{Ne}}^{+}$), 6.5 (${\mathrm{Ne}}_{2}^{+}$), 1.60 (${\mathrm{A}}^{+}$), 2.65 (${\mathrm{A}}_{2}^{+}$), 0.90 (${\mathrm{Kr}}^{+}$), 1.21 (${\mathrm{Kr}}_{2}^{+}$), 0.58 (${\mathrm{Xe}}^{+}$), and 0.79 (${\mathrm{Xe}}_{2}^{+}$). These values are in good agreement with available theoretical results. Our measurements join smoothly at higher ion energies with the measurements made by Hornbeck and by Varney except in the case of ${\mathrm{A}}_{2}^{+}$. In addition, our results indicate that earlier measurements at near-thermal energy by Tyndall and collaborators refer to the molecular ions in helium and neon, and to the atomic ions in krypton and xenon.

The Drift Velocities of Molecular and Atomic Ions in Helium, Neon, and Argon

Drift velocity measurements as a function of $\frac{E}{{p}_{0}}$ the ratio of field strength to normalized gas pressure, are presented for atomic and molecular ions of He, Ne, and A in their respective parent gases. Identification of the molecular ions is based upon the time resolution of the apparatus and the dependence of ion concentration on pressure, applied voltage, and gas purity. Extrapolation of the low field measurements to zero field yields mobility values for atomic ions, ${\ensuremath{\mu}}_{0}({\mathrm{He}}^{+})=10.8$ ${\mathrm{cm}}^{2}$/volt sec, ${\ensuremath{\mu}}_{0}({\mathrm{Ne}}^{+})=4.4$, and ${\ensuremath{\mu}}_{0}({\mathrm{A}}^{+})=1.63$ in good agreement with theory: Massey and Mohr compute ${\ensuremath{\mu}}_{0}({\mathrm{He}}^{+})=11$, and Holstein gives ${\ensuremath{\mu}}_{0}({\mathrm{Ne}}^{+})=4.1$ and ${\ensuremath{\mu}}_{0}({\mathrm{A}}^{+})=1.64$. Drift velocity data at low field for the molecular ions agree within experimental error with data of Tyndall and Powell (He), and Munson and Tyndall (Ne and A), which they assigned to atomic ions. A qualitative description in terms of ion-atom interaction forces is given for the observed field variation of the atomic ion drift velocities up to high $\frac{E}{{p}_{0}}$.

Mobility of positive alkali ions in argon, neon and helium

In a previous paper we described the application of new methods of measuring the mobility of ions to the case of positive ions of helium moving through helium gas. We also gave an example of the profound effect of traces of impurities in giving rise to groups of ions moving at speeds different from that of helium ions. This result is contrary to those obtained in many earlier investigations on the mobility of ions produced in one gas and measured in another. It was found that such ions could not be distinguished in their mobility from an ion of the gas in which the measurements were made. This is explained by the fact that, judged by present standards, the gas in all these early experiments was very impure and the ions consisted of clusters of polar molecules. Moreover, except in the case of the radio-active recoil atoms investigated by Rutherford and by Franck, which have a low ionisation potential, the conditions were often favourable for a transfer of charge from the original ion to some other atom or molecule, so that even the core of the cluster may not have been that of the original ion. In the determination of the mobility of different ions in a gas, the positive ions may be produced from Kunsman sources of the alkalies or alkaline earths, or from a glow discharge in a gas containing small amounts of known impurities. The present paper describes the results obtained in argon, neon and helium by the first method using ions of sodium, potassium, rubidium and cæsium.

Ionization Potentials and Probabilities for the Formation of Multiply Charged Ions in Helium, Neon and Argon

The multiply charged ions in helium, neon and argon have been studied with a mass spectrograph previously described. In helium the ${\mathrm{He}}^{+}$ ion showed up strongly but only faint evidence for the formation of ${\mathrm{He}}^{++}$ was found and no quantitative data for its relative intensity could be obtained. Neon yie ded the three ions ${\mathrm{Ne}}^{+}$,${\mathrm{Ne}}^{2+}$ and ${\mathrm{Ne}}^{3+}$ as the result of single electron impacts occurring respectively at minimum electron energies of 21.5, 63, and 125 volts. Curves which illustrate the efficiency for the formation of these ions expressed in number of ions per electron per cm per mm pressure at 0\ifmmode^\circ\else\textdegree\fi{}C as a function of the electron velocity exhibit maxima for ${\mathrm{Ne}}^{+}$ and ${\mathrm{Ne}}^{2+}$ of 2.75 and 0.16 at 150 and 250 volts respectively. In argon the five ions ${\mathrm{A}}^{+}$,${\mathrm{A}}^{2+}$,${\mathrm{A}}^{2+}$, ${\mathrm{A}}^{4+}$ and ${\mathrm{A}}^{5+}$ were observed. The ionization potentials for the first four were found to be respectively, 15.7, 44, 88 and 258 volts for single impact. The efficiency curves show maxima of 11.4, 1.1 and 0.04 at 50, 115 and 250 volts for ${\mathrm{A}}^{+}$,${\mathrm{A}}^{2+}$ and ${\mathrm{A}}^{3+}$ respectively. In the curves for ${\mathrm{Ne}}^{3+}$ and ${\mathrm{A}}^{4+}$ are found several upward breaks beyond their ionization potentials which indicate other higher critical potentials for their formation.