193-nm Photodissociation of ions from saturated and unsaturated aliphatic molecules

Abstract

To determine the analytical utility of photodissociation as a general fragmentation technique for tandem mass spectrometry of organic ions, the ability to fragment those ions considered least likely to absorb photons efficiently was investigated. To this end, the ability to photodissociate ions of aliphatic compounds by using 193-nm photons has been studied. Three fragment ions, the C4H 9 (+) ion from n-hexane, the C4H 7 (+) ion from 2-hexene, and C4H 5 (+) from 2-hexyne, have been photodissociated. The fragmentation efficiencies for all three ions studied were between 25 and 45%. The photofragment ion spectrum for each precursor ion studied is made up of characteristic fragments. These spectra demonstrate the ability to photodissociate aliphatic ions that originate from both saturated and unsaturated molecules. This provides substantial hope that virtually all organic ions will be able to be photodissociated by using 193-nm photons.

Electronic spectrum and photodissociation chemistry of the linear methyl propargyl cation H2C4H3+

“…Following photoexcitation at 193 nm, the H 2 C 4 H 3 + cation produced a charged photoproduct at m/z 27, almost certainly protonated acetylene (C 2 H 3 + ). 13 Collision induced dissociation of H 2 C 4 H 3 + also produced C 2 H 3 + through a process that was postulated to involve cyclization prior to fragmentation. 10 Recently Pei and Farrar investigated reactive collisions between C + and C 3 H 5 , which occur on the C 4 H 5 + potential energy surface, using velocity map imaging to probe the energy disposal in the reaction.…”

Photodissociation of singly protonated peptides at 193 nm investigated with tandem time‐of‐flight mass spectrometry

“…Photodissociation (PD) has been used over the years to study the structure and reaction dynamics of polyatomic ions 1–3. Recently, its analytical potential for ion activation has been further recognized, and progress is being made to develop it as a useful tool in combination with tandem mass spectrometry for the analysis of biomolecules, peptides and proteins in particular 4–21.…”

Electronic Spectrum and Photodissociation Chemistry of the 1-Butyn-3-yl Cation, H3CCHCCH+

“…There have been several previous investigations of C 4 H 5 + dissociation. Photofragmentation at 193 nm of C 4 H 5 + generated from 2-hexyne mainly produced C 2 H 3 + photofragments . Collision induced dissociation of C 4 H 5 + , presumably the MP isomer, also gave nearly exclusively C 2 H 3 + fragments, with the dissociation proposed to proceed through a low energy cyclic isomer .…”