This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/rcm.8635 This article is protected by copyright. All rights reserved. Rodrigues-Oliveira André (Orcid ID: 0000-0002-5279-4012) Daiki Yamada Bruno (Orcid ID: 0000-0001-8389-6487) Bastos Erick (Orcid ID: 0000-0002-0592-9455) Correra Thiago (Orcid ID: 0000-0002-8422-8701) Development of a Photoinduced Fragmentation Ion Trap for Infrared Multiple Photon Dissociation Spectroscopy Tatiana C. Penna, Gustavo Cervi, André F. Rodrigues-Oliveira, Bruno D. Yamada, Rafael Z. C. Lima, Jair J. Menegon, Erick L. Bastos and Thiago C. Correra* Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil *Corresponding author: tcorrera@iq.usp.br Abstract Rationale: Methods for isomer discrimination by mass spectroscopy are of increasing interest. Here we describe the development of a 3D ion trap for Infrared Multiple Photon Dissociation (IRMPD) spectroscopy that enables the acquisition of the infrared spectrum of selected ions in the gas phase. This system is suitable for the study of myriad chemical systems, including isomer mixtures. Methods: A modified 3D ion trap was coupled to a CO2 laser and an OPO/OPA system operating in the 2300 to 4000 cm –1 range. DFT vibrational frequency calculations were carried out to support spectral assignment. Results: Detailed descriptions of the interface between the laser and the mass spectrometer, the hardware to control the laser systems, the automated system for IRMPD spectrum acquisition and data