Gas-phase action spectroscopy of protoporphyrin IX (PP) and zinc-PP anions from 210nm to 720nm

Photoelectron spectroscopy of the protoporphyrin IX dianion

“…Decarboxylation (reaction 2) is also a commonly observed process in photodetachment and is driven by the thermodynamic stability of CO 2 . [47][48][49] Decarboxylation of PPwas previously observed by Wyer et al 15 The near eKE = 0 eV feature in the ns spectra shown in figure 2 is due to thermionic emission from monoanions (green dashed lines), as evidenced by the appearance of electrons below the RCB. As this feature is only observed when using a ns laser, the formation of the monoanions is a multiple photon process occurring on a slower timescale than the pulse duration of the fs laser.…”

“…To date there have been two gas phase measurements of the absorption spectrum of protoporphyrin IX anions. 5,15 Wyer et al recorded the gas phase photodissociation action spectra of deprotonated protoporphyrin IX anion and ZnPP -, by monitoring the formation of neutral fragments in an electrostatic storage ring. 15 Following the absorption of a photon, internal conversion back to the electronic ground state produced vibrationally excited anions, which dissociated into anionic and neutral fragments.…”

Neuroglobin Provides a Convenient Scaffold to Investigate the Triplet-State Properties of Porphyrins by Time-Resolved EPR Spectroscopy and Magnetophotoselection

“…1 We observe an influence of the axial ligand on the absorption spectrum in terms of spectral shifts, in both the Soret and Q-band regions, as a function of the increased content of pyridine in the solvent mixture, in agreement with past experiments performed on ZnPP [40]. According to the literature, the Q transitions have been tentatively assigned to either the two distinct Q x and Q y transitions or two vibronic transitions Q(0-1) and Q(0-0) for Zn(II) porphyrin systems [41][42][43][44]. From the point of view of the triplet-state spectrum, the spin-polarization pattern remains unaffected by increasing the amount of coordinating pyridine solvent, while the turning points corresponding to the X and Y transitions become more defined.…”

The electronic structure and deexcitation pathways of an isolated metalloporphyrin ion resolved by metal L-edge spectroscopy

“…Previous mass-spectrometric studies on electrosprayed metal protoporphyrin IX ions employed collision-induced dissociation (CID), [24][25][26][27] electron-capture-induced dissociation (ECD) 28 and laser-induced dissociation (LID) 18,25,26,[29][30][31][32] following absorption at the Soret and Q bands to investigate their dissociation processes. Moreover, it has been shown for gas-phase heme + that photoexcitation in the UV/vis region can be followed by dissociation via two kinetically competing channels on a microsecond to millisecond timescale.…”