ALMA Detection of Interstellar Methoxymethanol (CH3OCH2OH)

We report the detection of interstellar methoxymethanol (CH₃OCH₂OH) in Atacama Large Millimeter/submillimeter Array (ALMA) Bands 6 and 7 toward the MM1 core in the high-mass star-forming region NGC 6334I at ∼0.″1-1″ spatial resolution. A column density of 4(2) × 10¹⁸ cm^-2 at T _ex = 200 K is derived toward MM1, ∼34 times less abundant than methanol (CH₃OH), and significantly higher than predicted by astrochemical models. Probable formation and destruction pathways are discussed, primarily through the reaction of the CH₃OH photodissociation products, the methoxy (CH₃O) and hydroxymethyl (CH₂OH) radicals. Finally, we comment on the implications of these mechanisms on gas-phase versus grain-surface routes operative in the region, and the possibility of electron-induced dissociation of CH₃OH rather than photodissociation.