Self-assembling of the neutral intermediate with chemically bound argon in photoexcited van der Waals complex Ar-I2

J Chem Phys. 2021 Sep 28;155(12):124308. doi: 10.1063/5.0059414.

Abstract

Photodissociation of the van der Waals complex Ar-I2 after excitation into the Rydberg states of I2 has been investigated with velocity map imaging of photofragments. Formation of the translationally hot ions of argon Ar+ with three modes in kinetic energy distribution has been revealed. The measured dependence of the kinetic energy of Ar+ on the pumping photon energy indicates the appearance of Ar+ from three channels of the photodissociation of the linear intermediate Ar+-I-I- containing chemically bound argon. These channels are (1) dissociation into Ar++ I2 -; (2) three-body dissociation into (Ar+)* + I* + I-, with (Ar+)* and I* being the 2P1/2 states of the species; and (3) two-body electron photodetachment, giving rise to Ar+ + I2 + e. Three indicated channels are similar to those established for the photodissociation of trihalide anions. This similarity confirms the conclusion on the formation of the Ar+-I-I- intermediate, which is isoelectronic to the trihalide anion Cl-I-I-. The mechanism of the Ar+-I-I- formation involves two-photon excitation of the complex Ar-I2 into the Rydberg state of I2 converted into the ion-pair state and further electron transfer from Ar to I+ of the ion-pair state. The self-assembling of the structure making the formation of the Ar+-I-I- intermediate energetically accessible is confirmed by modeling the dynamics in the excited linear complex Ar-I2. Photoexcitation of the van der Waals complexes of noble gases with halogens into the ion-pair states of halogen is supposed to be a promising approach for generating the new chemical compounds of noble gas atoms.