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Laser desorption mass spectrometry was employed to study rubrene using three different sample preparation methods. Pressed-pellet and films drop-cast from solution were investigated with a laser-desorption time-of-flight spectrometer. Jet-cooled rubrene cations were produced in a supersonic molecular beam by laser desorption from a film-coated metal rod and detected with time-of-flight mass spectrometry. The films for this process were produced by vacuum sublimation of powder samples. The mass spectra from each of these samples contained the parent molecular ion and fragments resulting from phenyl ring elimination - a pattern similar to that produced by electron impact ionization. The amount of fragmentation varied with sample preparation and desorption laser wavelength. The rubrene cation was mass selected and studied with UV laser photodissociation at 355 nm. The resulting fragmentation mass spectrum indicated the loss of one or two phenyl groups, but no more than this. Computational studies of the ion energetics were used to investigate the stable fragment ion structures and understand the energetics of the dissociation process. 

A new electronic transition is reported for the linear C 6 + cation with an origin at 416.8 nm. This spectrum can be compared to the matrix isolation spectra at lower energies reported previously by Fulara et al. [J. Chem. Phys. 123, 044305 (2005)], which assigned linear and cyclic isomers, and to the gas phase spectrum reported previously by Campbell and Dunk [Rev. Sci. Instrum. 90, 103101 (2019)], which detected the same cyclic-isomer spectrum reported by Fulara. Comparisons to electronically excited states and vibrations predicted by various forms of theory allow assignment of the spectrum to a new electronic state of linear C 6 + . The spectrum consists of a strong origin band, two vibronic progression members at higher energy and four hot bands at lower energies. The hot bands provide the first gas phase information on ground state vibrational frequencies. The vibrational and electronic structure of C 6 + provide a severe challenge to computational chemistry. 

The Zn+(methanol) ion molecule complex produced by laser vaporization is studied with photofragment imaging at 280 and 266 nm. Photodissociation produces the methanol cation CH3OH+ via excitation of a charge-transfer excited state. Surprisingly, excitation of bound excited states produces the same fragment via a curve crossing prior to separation of products. Significant kinetic energy release is detected at both wavelengths with isotropic angular distributions. Similar experiments are conducted on the perdeuterated methanol complex. The Zn+ cation is a minor product channel that also exhibits significant kinetic energy release. An energetic cycle using the ionization energies of zinc and methanol together with the kinetic energy release produces an upper limit on the Zn+-methanol bond energy of 33.7 ± 4.2 kcal/mol (1.46 ± 0.18 eV).