Breakdown of ionic character of molecular alkali bromides in inner-valence photoionization

Abstract

The inner-valence region of alkali bromide XBr (X=Li, Na, K, Rb) vapours has been studied experimentally by means of synchrotron radiation excited photoelectron spectroscopy. Experimental spectra were analyzed by comparing them with available theoretical results and previous experiments. Ionic character of alkali bromides is seen to change in the inner-valence region with increasing atomic number of the alkali atom. A mechanism involving mixing between Br 4s and Rb 4p orbitals has been suggested to account for the fine structure observed in inner-valence ionization region of RbBr.

Behavior of relative state selective photoionization cross sections of RbBr molecules in the valence region

“…The satellite structures, which can be observed in the valence photoelectron spectrum of RbBr (Fig. 1) in the ionization energy region of 24-35 eV, were not fully accounted for in the calculations [8].…”

“…All the most prominent features are labeled with capital letters and are normalized to the D line for better visual presentation of the relative intensity distribution. The D line represents a pure Rb Ap~] state based on calculations [8]. Peak A originates mainly from ionization of the Br 4s orbital, while peaks C, D, E, and F exhibit mainly Rb Ap character.…”

“…Benzaid et al [5] reported a com prehensive experim ental study o f the partial photoionization cross sections o f atom ic B r across the entire autoionization regim e extending from the first ionization threshold B r+ (3P 2) to the highest threshold B r+ (] So). T he autoionization decay patterns arising from the *oleksandr.karpenko@oulu.fi Recently, K arpenko et al [7,8] show ed that the third-order algebraic diagram m atic construction (AD C) m ethod [9,10] im plem ented in the DIRAC 10 program [11] is capable of reproducing valence and inner-valence photoelectron spectra …”

“…(Color online) IhtAp/As intensity ratios of RbBr and Kr[20,21] as a function of photon energy.four groups of spectral features assigned to Br 4 p~\ Br 4 s_I, Rb 4 p~\ and Rb 4.v-1 can be found in the ionization energy region between 5 and 45 eV[8].…”