Measurement of dynamic atomic polarizabilities of Al at 19 wavelengths from 420 nm to 680 nm in electrical exploding wire experiments.

Abstract

The dynamic polarizabilities of Al atom at 19 wavelengths from 420 nm to 680 nm are measured experimentally for the first time. A 15 µm diameter Al wire is heated to the gas/ microdrop stage using a 3 kA, 25 ns pulsed current, and the energy deposition when the resistive voltage reaches its peak is 4.7 eV·atom-1, which is higher than the atomization enthalpy of Al but much lower than its first ionization potential. Two laser interferometric images of the Al gas are obtained simultaneously using a 532 nm laser and an optical parametric oscillator laser. Then an integrated phase method is used to reconstruct the Al atomic linear density distribution based on the known atomic polarizability at 532 nm, which acts as a bridge between the two interferograms to obtain the relative atomic polarizability value at a specific wavelength with respect to the value at 532 nm. The measured dynamic polarizability of Al atom decreases from 13.5×10-24 cm3 to 9.4×10-24 cm3 as the wavelength increases from 420 nm to 680 nm with a measurement error of approximately ±10%. The experimental result fits well with an uncoupled Hartree-Fock approximation, and the reconstructed static polarizability of 8.13 ± 0.79×10-24 cm3 is well matched with reference measurement results.