ALMA Detection of Interstellar Methoxymethanol (CH₃OCH₂OH)

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We report the detection of interstellar methoxymethanol (CH₃OCH₂OH) in 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) x 10¹⁸ cm⁻² at Tex = 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 vs grain-surface routes operative in the region, and the possibility of electron-induced dissociation of CH₃OH rather than photodissociation.