Detection of sub-GeV Dark Matter and Solar Neutrinos via Chemical-Bond
  Breaking
  We explore a new low-threshold direct-detection concept for dark matter,
based on the breaking of chemical bonds between atoms. This includes the
dissociation of molecules and the creation of defects in a lattice. With
thresholds of a few to 10's of eV, such an experiment could probe the nuclear
couplings of dark matter particles as light as a few MeV. We calculate the
expected rates for dark matter to break apart diatomic molecules, which we take
as a case study for more general systems. We briefly mention ideas for how
chemical-bond breaking might be detected in practice. We also discuss the
possibility of detecting solar neutrinos, including pp neutrinos, with this
experimental concept. With an event rate of $\mathcal{O}$(0.1/kg-year), large
exposures are required, but measuring low-energy solar neutrinos would provide
a crucial test of the solar model.
