  The cold emission of particles from surfaces under intense electric fields is
a process which underpins a variety of applications including atom probe
tomography (APT), an analytical microscopy technique with near-atomic spatial
resolution. Increasingly relying on fast laser pulsing to trigger the emission,
APT experiments often incorporate the detection of molecular ions emitted from
the specimen, in particular from covalently or ionically bonded materials.
Notably, it has been proposed that neutral molecules can also be emitted during
this process. However, this remains a contentious issue. To investigate the
validity of this hypothesis, a careful review of the literature is combined
with the development of new methods to treat experimental APT data, the
modelling of ion trajectories, and the application of density-functional theory
(DFT) simulations to derive molecular ion energetics. It is shown that the
direct thermal emission of neutral molecules is extremely unlikely. However,
neutrals can still be formed in the course of an APT experiment by dissociation
of metastable molecular ions.
