ALMA Detection of Interstellar Methoxymethanol (CH$_3$OCH$_2$OH)
  We report the detection of interstellar methoxymethanol (CH$_3$OCH$_2$OH) 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 $10^{18}$
cm$^{-2}$ at $T_{ex}$ = 200 K is derived toward MM1, ~34 times less abundant
than methanol (CH$_3$OH), and significantly higher than predicted by
astrochemical models. Probable formation and destruction pathways are
discussed, primarily through the reaction of the CH$_3$OH photodissociation
products, the methoxy (CH$_3$O) and hydroxymethyl (CH$_2$OH) 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 CH$_3$OH rather than photodissociation.
