  Substituted naphthalene anions (deprotonated 2-naphthol and
6-hydroxy-2-naphthoic acid) are spectroscopically probed in a tandem drift tube
ion mobility spectrometer (IMS). Target anions are selected according to their
drift speed through nitrogen buffer gas in the first IMS stage before being
exposed to a pulse of tunable light that induces either photodissociation or
electron photodetachment, which is conveniently monitored by scavenging the
detached electrons with trace \ce{SF6} in the buffer gas. The photodetachment
action spectrum of the 2-naphtholate anion exhibits a band system spanning
380-460\,nm~with a prominent series of peaks spaced by 440\,\cme, commencing at
458.5\,nm, and a set of weaker peaks near the electron detachment threshold
corresponding to transitions to dipole-bound states. The two deprotomers of
6-hydroxy-2-naphthoic acid are separated and spectroscopically probed
independently. The molecular anion formed from deprotonation of the hydroxy
group possesses a photodetachment action spectrum similar to that of the
2-naphtholate anion with an onset at 470\,nm and a maximum at 420\,nm. Near
threshold, photoreaction with \ce{SF6} is observed with displacement of an OH
group by an F atom. In contrast, the anion formed from deprotonation of the
carboxylic acid group features a photodissociation action spectrum, recorded on
the \ce{CO2} loss channel, lying to much shorter wavelength with an onset at
360\,nm and maximum photoresponse at 325\,nm.
