Specification of the Ionization Potential of AlI

Abstract

A joint analysis of high-precision microwave measurements of transition frequencies of Al atoms in S, P, D, and F Rydberg states obtained by the authors and spectroscopic data from optic wavelength range allowed us to determine a new value for ionization potential of Al atoms V IP = 48278,53±0,02 cm -1 .Ionization potentials V IP of atoms and molecules are fundamental quantities of great importance in many areas of physics and chemistry. They provide crucial information on the electronic structure and, therefore, are often used as benchmarks for theoretical methods. Also when used in the appropriate thermodynamic cycles, V IP relate to bond strengths. The accuracy of calculation of ionization potentials of multi electron atoms for the time being is not satisfactory and that is why they are determined using experimental methods: method of surface ionization, method of electron impact, method of spectral extrapolation, method of two and three stage ionization, and method of fitting Rydberg series. The last method is accepted as providing the highest accuracy of 1 cm -1 and higher. The authors of works [1][2][3][4][5] used this method to determine the ionization potential of Al atoms. We propose a method of specification of the ionization potential that based on the joining of the most accurate direct measurements of transition frequencies from the ground state to the excited states of the atom in optic wavelength range T nlj with highprecision calculations of atomic energy E(n,l,j) in Rydberg states. We used this method earlier for specification of ionization potential of Au I [6]. In the present paper we apply this method to the specification of ionization potential V IP of aluminum. Therefore we have: