Formation pathways of formic acid (HCOOH) in regions with methanol ices

Abstract

We modeled the collisions between OH^+ projectiles with kinetic energies ranging from 10 to 22 eV and an amorphous cold (CH3OH)_10 substrate using Born-Oppenheimer molecular dynamics (BOMD) simulations. We conducted the simulations for a collision time of 400 femtoseconds (fs), during which we followed multiple bond-forming and breaking reactions. Here, we report four new pathways for the formation of formic acid HCOOH . We find new precursors such as CH3(OH)2+ HC(OH)2^+ CH2OH^+ and CH2(OH)2 which are essential in these pathways for the formation of formic acid. The methanodiol CH2(OH)2 and hydroxymethyl CH2OH^+ cations have previously been identified as key precursors of formaldehyde. These pathways suggest new ways to form formic acid in methanol ice mantles on dust grains, offering alternative mechanisms leading to the formation of complex organic molecules (COMs) in space.