Wavelength-dependent photodissociation of iodomethylbutane

Ultrashort XUV pulses of the Free-Electron-LASer in Hamburg (FLASH) were used to investigate laser-induced fragmentation patterns of the prototypical chiral molecule 1-iodo-2-methyl-butane (C₅ H₁₁I) in a pump-probe scheme. Ion velocity-map images and mass spectra of optical-laser-induced fragmentation were obtained for subsequent FEL exposure with photon energies of 63 eV and 75 eV. These energies specifically address the iodine 4d edge of neutral and singly charged iodine, respectively. The presented ion spectra for two optical pump-laser wavelengths, i.e., 800 nm and 267 nm, reveal substantially different cationic fragment yields in dependence on the wavelength and intensity. For the case of 800-nm-initiated fragmentation, the molecule dissociates notably slower than for the 267 nm pump. The results underscore the importance of considering optical-laser wavelength and intensity in the dissociation dynamics of this prototypical chiral molecule that is a promising candidate for future studies of its asymmetric nature.. Authors: Music, Valerija [Universität Hamburg (Germany); Universität Kassel (Germany); European XFEL, Schenefeld (Germany)]; Allum, Felix [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Institute (PULSE); Univ. of Oxford (United Kingdom)]; Inhester, Ludger [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Center for Free-Electron Laser Science]; Schmidt, Philipp [Universität Kassel (Germany); European XFEL, Schenefeld (Germany)]; Boll, Rebecca [European XFEL, Schenefeld (Germany)]. DOE Contract: AC02-76SF00515. Subjects: 74 ATOMIC AND MOLECULAR PHYSICS