In astrochemistry, the open-shell (radical) cations of diamondoids are of special interest as they absorb lower energy photons in comparison to their neutral counterparts and may potentially be formed in interstellar medium by ionization with photons and/or cosmic rays . Thus, several recent studies have targeted the optical spectra of radical cations of diamondoids . Specifically, the optical spectrum of Ada + has been obtained by electronic photodissociation (EPD) spectroscopy by Crandall et al. and helium-tagged electronic spectroscopy by Kappe et al. . In addition, the EPD study by Crandall et al. has provided insight into photoinduced fragmentation of Ada + . The optical spectrum of the diamantane cation, Dia + , has also been recently reported by the same group .