The use of Förster resonance energy transfer (FRET) as a probe of the structure of biological molecules through fluorescence measurements in solution is well attested. The transposition of this technique to the gas phase is appealing since it opens the perspective of combining the structural accuracy of FRET with the specificity and selectivity of mass spectrometry (MS). Here, we report FRET results on gas phase poly-alanine ions obtained by measuring FRET efficiency through specific photo-fragmentation rather than fluorescence. The structural sensitivity of the method was tested using commercially-available chromophores (QSY 7 and carboxyrhodamine 575) grafted on a series of small, alanine based peptides of differing sizes. The photo-fragmentation of these systems was investigated through action-spectroscopy, and their conformations were probed using ion mobility spectrometry (IMS) and Monte Carlo-minimization (MCM) simulations. We show that specific excitation of the donor chromophore results in the observation of fragments that are specific to the electronic excitation of the acceptor chromophore. This shows that energy transfer took place between the two chromophores and hence that the action-FRET technique can be used as a new and sensitive probe of the structure of gas phase biomolecules, which opens perspectives as a new tool in structural biology.