Energy transfer reaction K(4s) + K(7s) \rightarrow K(4s) + K(5f), theory compared with experiment

A comparison between theory and experiment, concerning the K(4s)+K(7s)\rightarrow K(4s)+K(5f) reaction of energy transfer in thermal collisions, is presented. Relevant cross sections are calculated for the potassium vapour temperatures in the range of 310-1000 K. They are based on the theoretical adiabatic K_2 potential energy curves and on the use of the multicrossing Landau-Zener model. In the temperature range of the present experiment, 428-451 K, the computed cross sections vary little, from 2.09x10^-14 cm^2 to 2.04x10^-14 cm^2, and agree well with the value 1.8(8)x10^-14 cm^2, which is the average of the corresponding experimental results.

Energy transfer reaction K(4s) + K(7s) → K(4s) + K(5f), theory compared with experiment

Abstract A comparison between theory and experiment, concerning the K(4 s) + K(7s)→K(4 s) + K(5f) reaction of excitation energy transfer in thermal collisions, is presented. The cross sections for this process are calculated for the potassium vapour temperatures in the range of 310–1000 K. The calculations are based on the theoretical adiabatic K2 potential energy curves and on the use of the multicrossing Landau-Zener model. The experiment was carried out using the method of spectroscopy with resolution in time. The signals of the direct-fluorescence decay from pulsed-laser-excited 7s state, and of the sensitized-fluorescence from 5f state, were registered and analysed. In the temperature …

Excitation transfer between the rubidium52Dfine-structure levels in collisions with ground-state rubidium atoms: Experiment and theory

Experimental and theoretical study of thenf-level lifetimes of potassium

The theoretical and experimental values of the 5f ,6 f ,7 f, and 8f radiative lifetimes of neutral potassium are reported. The reduced matrix elements for all allowed electric-dipole nf5/2-nd5/2, nf5/2-nd3/2, and nf7/2-nd5/2 transitions with n =5–8 in K arecalculated using the relativistic linearized coupled-cluster method with single and double excitations of Dirac-Fock wave functions included to all orders in many-body perturbation theory. The resulting electric-dipole matrix elements are used to evaluate the lifetimes of the 5f ,6 f ,7 f, and 8f states in neutral K and their uncertainties. The contributions from the nf5/2-ng7/2, nf7/2-ng7/2, and nf7/2-ng9/2 transitions to the lifetimes o…

All-experimental values of self-quenching cross-sections for nf states (n=5-8) of potassium atoms

All-experimental self-quenching cross-sections σ nf are reported for K(nf) states (n = 5, 6, 7, 8). The experiment was performed at varied temperatures of K vapour in a spectral cell. Time-resolved fluorescence was observed following pulsed step-wise excitation with dipole and quadrupole transitions K(4s) → K(4p) → K(nf). The values: σ 5f = 2.4 ± 1.7, σ 6f = 4.5±1.4, σ 7f = 8.1±1.8, and σ 8f = 18.2±3.0 (in units of 10−13 cm−1) were obtained from a Stern-Volmer-type plot.