# Photon emission and atomic collision processes in two-phase argon doped with xenon and nitrogen

## TL;DR

This paper analyzes photon emission and atomic collision processes in two-phase argon doped with xenon and nitrogen, aiming to improve scintillation signals for dark matter and neutrino detectors, and questions a recent hypothesis about excitation transfer enhancement.

## Contribution

It provides a comprehensive analysis of emission and collision processes in doped argon and challenges the hypothesis of excitation transfer enhancement at low temperatures.

## Key findings

- The hypothesis of excitation transfer enhancement is likely incorrect.
- Resonant excitation transfer via ArN2 van der Waals molecules is proposed as an alternative mechanism.
- Implications for improving photon collection in particle detectors.

## Abstract

We present a comprehensive analysis of photon emission and atomic collision processes in two-phase argon doped with xenon and nitrogen. The dopants are aimed to convert the VUV emission of pure Ar to the UV emission of the Xe dopant in the liquid phase and to the near UV emission of the N2 dopant in the gas phase. Such a mixture is relevant to two-phase dark matter and low energy neutrino detectors, with enhanced photon collection efficiency for primary and secondary scintillation signals. Based on this analysis, we show that the recently proposed hypothesis of the enhancement of the excitation transfer from Ar to N2 species in the two-phase mode is either incorrect or needs assumption about a new extreme mechanism of excitation transfer coming into force at lower temperatures, in particular that of the resonant excitation transfer via ArN2 compound (van der Waals molecule).