We report cross-section measurements of the associative-ionization process, Na(3 ${\mathit{p}}^{2}$ ${\mathit{P}}_{3/2}$ )+Na(3 ${\mathit{p}}^{2}$ ${\mathit{P}}_{3/2}$ )\ensuremath{\rightarrow} ${\mathrm{Na}}_{2}^{+}$ +e as a function of velocity, alignment, and orientation in the collision energy range from 300 to 5 K. Two independently tunable laser beams select narrow velocity classes of excited sodium in a well-collimated atomic beam. Circular and linear polarization of the excitation lasers permits alignment and orientation of the excited atoms in the two velocity classes. The excitation functions show pronounced differences reflecting different molecular pathways to the final product, and they bridge the energy range between conventional and ``cold'' collision dynamics.We report cross-section measurements of the associative-ionization process, Na(3${\mathit{p}}^{2}$${\mathit{P}}_{3/2}$)+Na(3${\mathit{p}}^{2}$${\mathit{P}}_{3/2}$)\ensuremath{\rightarrow}${\mathrm{Na}}_{2}^{+}$+e as a function of velocity, alignment, and orientation in the collision energy range from 300 to 5 K. Two independently tunable laser beams select narrow velocity classes of excited sodium in a well-collimated atomic beam. Circular and linear polarization of the excitation lasers permits alignment and orientation of the excited atoms in the two velocity classes. The excitation functions show pronounced differences reflecting different molecular pathways to the final product, and they bridge the energy range between conventional and ``cold'' collision dynamics.

Physical Review AJul 1, 199013 citations

Molecular beam diagnostics with internal state selection: Velocity distribution and dimer formation in a supersonic Na/Na2 beam

Klaas Bergmann, Ulrich Hefter, P. Hering

Chemical PhysicsAug 1, 197891 citations

Alignment of Sodium Atoms

W. Bruce Hawkins

Physical ReviewOct 15, 19548 citations

Coherence in Penning Ionization and First Kind Collisions: Volume Recombination of Ions/Electrons.

L. D. Schearer, W. F. Parks

A thermal energy beam of helium atoms in the metastable state is used to coherently excite ions of Sr, Ca, and Ba in a Penning collision. The anisotropic excited state distributions appears as Polarized line emission from the excited ions. The degree of ion alignment may be used to determine the populations of the quasi-molecular states of the ion-atom pair. The coherent emission is also utilized to obtain Hanle signals from which the radiative decay rate of the excited ion is determined. This is the first case in which coherence is produced in a collision process involving Penning ionization. The alignment of the Penning ions is an important new parameter in the description of these reactions. In an effort to extend such observations to molecular systems a nitrogen molecular metastable beam source was demonstrated. The use of metal vapor targets and the excitation rate of the excited states of Cd and Zn in energy transfer collisions with the N2(m) enable us to determine the vibrational distribution of the A 3Sigma state of N2 in the beam. Energy transfer cross sections and some Penning cross sections were measured in the beam system. (Author)A thermal energy beam of helium atoms in the metastable state is used to coherently excite ions of Sr, Ca, and Ba in a Penning collision. The anisotropic excited state distributions appears as Polarized line emission from the excited ions. The degree of ion alignment may be used to determine the populations of the quasi-molecular states of the ion-atom pair. The coherent emission is also utilized to obtain Hanle signals from which the radiative decay rate of the excited ion is determined. This is the first case in which coherence is produced in a collision process involving Penning ionization. The alignment of the Penning ions is an important new parameter in the description of these reactions. In an effort to extend such observations to molecular systems a nitrogen molecular metastable beam source was demonstrated. The use of metal vapor targets and the excitation rate of the excited states of Cd and Zn in energy transfer collisions with the N2(m) enable us to determine the vibrational distribution of the A 3Sigma state of N2 in the beam. Energy transfer cross sections and some Penning cross sections were measured in the beam system. (Author)

Dec 1, 19790 citations

We report cross-section measurements of the associative-ionization process, Na(3

{\mathit{p}}^{2}

{\mathit{P}}_{3/2}

)+Na(3

{\mathit{p}}^{2}

{\mathit{P}}_{3/2}

)\ensuremath{\rightarrow}

{\mathrm{Na}}_{2}^{+}

+e as a function of velocity, alignment, and orientation in the collision energy range from 300 to 5 K. Two independently tunable laser beams select narrow velocity classes of excited sodium in a well-collimated atomic beam. Circular and linear polarization of the excitation lasers permits alignment and orientation of the excited atoms in the two velocity classes. The excitation functions show pronounced differences reflecting different molecular pathways to the final product, and they bridge the energy range between conventional and ``cold'' collision dynamics.