João Ameixa

Postdoctoral Researcher

Email: j.ameixa@campus.fct.unl.pt

Publons ID: 5301475

Research Areas

In my research I focus on multiscale radiation damage to DNA by combining interdisciplinary knowledge from physics, radiation biology, biophysics as well as DNA bionanotechnology. In addition, I made advances in the field of gas-phase molecular dynamics with implications in astrochemistry, nanomedicine and biochemistry through studies on (i) electron attachment to novel radiosensitizer agents for cancer radiation therapy (OTfU, benzaldehyde, tirapazamine), (ii) the electron-induced fragmentation of chromium hexacarbonyl, a precursor for focused electron beam-induced deposition of metallic nanostructures, (iii) the electron attachment properties of subunits of ubiquinone, and NADH mitochondrial electron carrier molecules, (iv) the survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium, and (v) the characterization of low-lying excited states of molecules detected in the interstellar medium using vacuum-ultraviolet (VUV) radiation. I have expertise in the operation of ion sources (electron monochromators, electrospray ionization sources), mass spectrometers (quadrupole, double-sector, reflectron time of flight), detectors (channel electron multiplier, multichannel plate, faraday plate), respective instrumentation and data acquisition systems, high-vacuum technology, atomic force microscopy (AFM), as well as have conducted experiments using synchrotron radiation and cryogenic ion-beam storage rings.

In my teaching activities, I focused on laboratory courses on physics to undergraduate science and engineering students covering topics of classical mechanics, thermodynamics, and electromagnetism. Further engaged in netwoeks at the European level as member of the COST Actions “MultiChem” CA20129 and “MD-GAS” CA18212.

Main Publications

Ameixa, J.; Arthur-Baidoo, E.; Pereira-da-Silva, J.; Ruivo, J. C.; Varella, M. T. do N.; Beyer, M. K.; Ončák, M.; Ferreira da Silva, F.; Denifl, S. Formation of temporary negative ions and their subsequent fragmentation upon electron attachment to CoQ0 and CoQ0H2. Chem. Phys. Chem. (2022). https://doi.org/10.1002/cphc.202100834 Front Cover

Ziegler, P.; Pelc, A.; Arthur-Baidoo, E.; Ameixa, J.; Ončák, M.; Denifl, S. Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule. RSC Adv. 11, 32425–32434 (2021). https://doi.org/10.1039/D1RA06083J

Gatchell, M.; Ameixa, J.; Ji, M.; Stockett, M. H.; Simonsson, A.; Denifl, S.; Cederquist, H.; Schmidt, H. T.; Zettergren, H. Survival of PAH knockout fragments in the interstellar medium. Nat. Commun. 121, 2021, 12, 1–8 (2021). https://doi.org/10.1038/s41467-021-26899-0

Arthur‐Baidoo, E.; Ameixa, J.; Ončák, M.; Denifl, S. Ring‐selective fragmentation in the tirapazamine molecule upon low‐energy electron attachment. Int. J. Mol. Sci. 22, 3159 (2021). https://doi.org/10.3390/ijms22063159

Arthur-Baidoo, E., Ameixa, J., Ziegler, P., Ferreira da Silva, F., Oncak, M., & Denifl, S. Reactions in Tirapazamine Induced by the Attachment of Low-Energy Electrons: Dissociation Versus Roaming of OH. Angew. Chemie-Int. Ed., 59 17177-17181 (2020). https://doi.org/10.1002/anie.202006675 Hot Paper

Pereira-da-Silva, J.; Rodrigues, R.; Ramos, J.; Brigído, C.; Botnari, A.; Silvestre, M.; Ameixa, J.; Mendes, M.; Zappa, F.; Mullock, S. J.; Araújo, J. M. M.; Varella, M. T. do N.; Cornetta, L. M.; Ferreira da Silva, F. Electron driven reactions in tetrafluoroethane: positive and negative ions formation. J. Am. Soc. Mass Spectrom., 32, 6, 1459–1468 (2021). https://doi.org/10.1021/jasms.1c00057

Tiefenthaler, L., Ameixa, J., Martini, P., Albertini, S., Ballauf, L., Zankl, M., Goulart, M., Laimer, F., Haeften, K. von, Zappa, F., and Scheier, P. An intense source for cold cluster ions of a specific composition. Review of Scientific Instruments 91, 033315 (2020). https://doi.org/10.1063/1.5133112