Charged Particle Imaging of the Deprotonated Octatrienoic Acid Anion: Evidence for a Photoinduced Cyclization Reaction

Abstract

. (2016) 'Charged particle imaging of the deprotonated octatrienoic acid anion : evidence for a photoinduced cyclization reaction.', The journal of physical chemistry letters., 7 (22). pp. 4635-4640. Further information on publisher's website:https://doi.org/10.1021/acs.jpclett.6b02302Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in The journal of physical chemistry letters, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see https://doi.org/10.1021/acs.jpclett.6b02302Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. (Figure 1) was generated by electrospray ionisation, mass-selected and intersected with laser pulses (~5 ns duration) at 4.13 eV (300 nm) or 4.66 eV (266 nm) at the centre of a perpendicular velocity-map imaging (VMI) spectrometer. 23,24 The VMI spectrometer has been optimised to perform photoelectron spectroscopy by gating the imaging detector with ~100 ns gate pulse and reconstructing the raw image. 25 However, the same perpendicular VMI spectrometer can also be used to image other charged species, such as H -. Supporting ground electronic structure calculations were performed at the G4 5 level of theory and resonance energetics computed at multi-state XCMQDPT2 level of theory. 26,27 The photoelectron spectra of [C7H9-CO2] -taken at hv = 4.13 eV and 4.66 eV are shown in Figure 1(a) and (b), respectively. The photoelectron spectra are dominated by a peak at low electron kinetic energy, eKE, which is generally indicative of the indirect electron loss process of thermionic emission. 15,20,28,29 In addition to this low eKE peak, there are several minor features at higher eKE. In the hν = 4.13 eV spectrum, the low eKE peak has a shoulder that extends up to ~1.4 eV and a weak feature that peaks at eKE ~ 2.5 eV as indicated by the asterisk in Figure 1(a). The photoelectron spectrum at hν = 4.66 eV, shown in Figure 1(b), is broadly similar, although the shoulder to the dominating low eKE peak is larger than at hν = 4.13 eV and extends to eKE ~1.9 eV, which is consistent with a direct photodetachment process. The hν = 4.66 eV spectrum does not, however, show the clear peak around eKE ~ 2.5 eV (or at eKE ~ 3.0 eV taking into account the additional photon energy).In addition to the peak at eKE ~ 2.5 eV in the hν = 4.13 eV photoelectron spectrum, a discernible peak is present at eKE ~ 3.3 eV, as indicated by the arrow in Fig...

Gas-phase studies of the retinal protonated Schiff base chromophore

“…This mechanism was later confirmed by Musbat et al using isotope labeling MS-MS [44]. Similar cyclization mechanisms have been shown before for larger carotenoids [47], and later photoelectron spectroscopy was used to demonstrate fragmentation via Diels-Alder cyclization of a small anionic polyene, [C 7 H 9 −CO 2 ] − [48]. Coughlan et al have shown that in solution the RPSB degrades in a process which also involves a Diels-Alder cyclization and forms a cyclic retinal derivative of mass 238 amu.…”

“…We expect that in the near future, advances in IMS resolution through techniques such as structures for losseless ion manipulation (SLIM) and trapped ion mobility spectrometry (TIMS) may improve our understanding of RPSB isomerization. A way forward may be to study simpler RPSB derivatives [31,48]. The RPSB studies exemplify the importance of using IMS as a structure selection stage in action-spectroscopy experiments, which we believe will become more and more common in the future.…”

Electronic structure of the para-dinitrobenzene radical anion: a combined 2D photoelectron imaging and computational study

“…Similar dynamics have been observed following photoexcitation in anions that then undergo ground state reactions. 54 The NO2 − PE spectrum can in fact explain much of the spectral broadening observed in Figure 1. In Figure 7, representative 1D PE spectra are shown along with simulated PE spectra for direct detachment from pDNB − and NO2 − .…”

Photoelectron imaging of PtI2− and its PtI− photodissociation product

“…resonances) and dissociation will compete with autodetachment. 17,[34][35][36][37] The relative decrease of the intensity of the I − feature compared to the direct detachment channels of PtI2 − can arise from a number of reasons in addition to the one noted above: the favourability of a one-photon process over two-photon process, the large apparent photodetachment crosssection of PtI2 − , and the absorption profile to the excited states of PtI2 − . At the low-energy spectral end, we did not succeed in acquiring a spectrum at hv = 3.1 eV, in part because our OPO has very weak output here and the cross section for detachment from iodide is low (near-This is the author's peer reviewed, accepted manuscript.…”