Energy pooling reactions between two Na* (3p) atoms specified according to magnetic substate combinations

Abstract

In a beam experiment the authors have studied the energy pooling reaction between two laser excited Na* (3p) atoms, where in the final state one of the sodium atoms is in the 5s or 4d state and the other in the ground state. They have determined all eight independent partial cross sections and coherence terms, specified according to the various magnetic substate combinations of the colliding Na* (3p) atoms, as a function of the collision velocity. This is the maximum information that can be extracted from the experiment given the symmetry of the detection scheme. By applying a weak magnetic field, to orient the Na* (3p) atoms, the authors were able to distinguish between the two partial cross sections sigma 11 and sigma 1-1, where the subscripts 11 and 1-1 refer to the initial magnetic substate combinations of the two collision partners. By using an electro-optical modulator the authors have furthermore improved the signal-to-noise ratio to an extent where it was possible to measure all coherence terms.

Wavelength-dependent photodissociation as a probe for vibrational energy distributions in molecular ions

“…In our experiment the Na + 2 ions are produced via associative ionization in so-called headtail collisions between two Na(3 2 P 3/2 , F = 3) atoms in a single thermal Na beam. Our atomic beam configuration is based upon the experimental apparatus described by Meijer et al [13] and Nijland et al [14]. The associative ionization volume with dimensions x × y × z = 5 × 0.7 × 8 mm 3 is located between the grids G1 and G2 of the electrode system, displayed schematically in figure 4.…”

“…For a → transition the angular fragment distribution is given by Yang et al [16] G(θ) ∝ 1 + βP 2 (cos θ) (14) with θ the angle between the laser polarization axis and the recoil direction, β the socalled asymmetry parameter and P 2 the second Legendre polynomial. Kortyna et al [5] find experimentally β = 1.83 ± 0.17, in agreement with the theoretical value of 2.0 for low rotational temperatures.…”

Associative ionization in collisions between excited Na atoms in the and the states

“…The experimental set-up is shown schematically in figure 2. The apparatus has been described previously in [7,15] and has been used in beam experiments on associative ionization and energy pooling, respectively, in collisions between Na * (3p; 2 P 3/2 ) atoms. In the experiment discussed in this paper a single sodium beam is used, which intersects the exciting laser beams at right angles.…”

“…In principle, a complete analysis in the J -picture involves a very large set of partial cross sections and coherence terms. For a detailed discussion on these cross sections and coherence terms we refer to [15,18]. This set has already been reduced considerably by the transformation from the F -to the J-picture, using the reasonable assumption that the nuclear spin (I = 3…”