High Resolution Threshold Photofragment Spectroscopy ofO2+(a4Πu→f4Πg)

A new technique of laser photofragment spectroscopy is introduced and applied to a study of transitions from the $v=4\mathrm{}$ level of the $a^4{\Pi }_{\mathrm{u}}$ state of ${\mathrm{O}}_2^{+}$ to predissociating levels of the $f^4{\Pi }_g$ state near the dissociation limit. A resolution of 0.5 MeV is obtained, and specific $\Omega ,J$ levels of the $a$ state are identified. Much higher resolution is possible.