Experimental and computational study of ethanolamine ices at astrochemical conditions

TL;DR

This study combines experimental spectroscopy, chemical modeling, and quantum calculations to investigate ethanolamine ices under astrochemical conditions, aiming to understand its formation, spectral features, and potential presence in star-forming regions.

Contribution

It provides the first temperature-dependent spectral data, chemical models including reaction pathways, and quantum estimates for ethanolamine and related species in astrochemical environments.

Findings

Surface reactions may significantly produce ethanolamine in warmer regions (60-90 K).

Modeled ethanolamine abundance aligns with observational upper limits in hot cores.

Theoretical constants for related species aid future astronomical identification.

Abstract

Ethanolamine (NH2CH2CH2OH) has recently been identified in the molecular cloud G+0.693-0.027, situated in the SgrB2 complex in the Galactic center. However, its presence in other regions, and in particular in star-forming sites, is still elusive. Given its likely role as a precursor to simple amino acids, understanding its presence in the star-forming region is required. Here, we present the experimentally obtained temperature-dependent spectral features and morphological behavior of pure ethanolamine ices under astrochemical conditions in the 2 - 12 micro meter (MIR) and 120 - 230 nm (VUV) regions for the first time. These features would help in understanding its photochemical behavior. In addition, we present the first chemical models specifically dedicated to ethanolamine. These models include all the discussed chemical routes from the literature, along with the estimated binding energies and activation energies from quantum chemical calculations reported in this work. We have found that surface reactions: CH2OH + NH2CH2 --> NH2CH2CH2OH and NH2 + C2H4OH --> NH2CH2CH2OH in warmer regions (60-90 K) could play a significant role in the formation of ethanolamine. Our modeled abundance of ethanolamine complements the upper limit of ethanolamine column density estimated in earlier observations in hot core/corino regions. Furthermore, we provide a theoretical estimation of the rotational and distortional constants for various species (such as HNCCO, NH2CHCO, and NH2CH2CO) related to ethanolamine that have not been studied in existing literature. This study could be valuable for identifying these species in the future.