Person: Marggi Poullaín, Sonia
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First Name
Sonia
Last Name
Marggi Poullaín
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
12 results
Search Results
Now showing 1 - 10 of 12
Item Imaging the photodissociation dynamics of internally excited ethyl radicals from high Rydberg states(Physical Chemistry Chemical Physics, 2023) Rubio Lago, Luis; Chicharro, David V.; Marggi Poullaín, Sonia; Zanchet, Alexandre; Koumarianou, Greta; Glodic, Pavle; Samartzis, Peter C.; García Vela, Alberto; Bañares Morcillo, LuisThe site-specific hydrogen-atom elimination mechanism previously reported for photoexcited ethyl radicals (CH3CH2) [D. V. Chicharro et al., Chem. Sci., 2019, 10, 6494] is interrogated in the photodissociation of the ethyl isotopologues CD3CD2, CH3CD2 and CD3CH2 through the velocity map imaging (VMI) detection of the produced hydrogen- and deuterium-atoms. The radicals, generated in situ from photolysis of a precursor using the same laser pulse employed in their excitation to Rydberg states, decompose along the Ca-H/D and Cb-H/D reaction coordinates through coexisting statistical and site-specific mechanisms. The experiments are carried out at two excitation wavelengths, 201 and 193 nm. The comparison between both sets of results provides accurate information regarding the primary role in the site-specific mechanism of the radical internal reservoir. Importantly, at 193 nm excitation, higher energy dissociation channels (not observed at 201 nm) producing low-recoil H/Datoms become accessible. High-level ab initio calculations of potential energy curves and the corresponding non-adiabatic interactions allow us to rationalize the experimental results in terms of competitive non-adiabatic decomposition paths. Finally, the adiabatic behavior of the conical intersections in the face of several vibrational modes – the so-called vibrational promoting modes – is discussed.Item Halogen-atom effect on the ultrafast photodissociation dynamics of the dihalomethanes CH2 ICl and CH2 BrI(Physical Chemistry Chemical Physics, 2018) Murillo Sánchez, Marta Luisa; Marggi Poullaín, Sonia; Bajo González, Juan José; Corrales Castellanos, María Eugenia; González Vázquez, Jesús; Sola Reija, Ignacio; Bañares Morcillo, LuisReal time photodissociation of dihalomethanes has been measured by femtosecond velocity map imaging to disentangle the effect of the halogen-atom on the carbon–iodine cleavage dynamics.Item Femtosecond XUV induced dynamics of the methyl iodide cation(2019) Reitsma, Geert; Murillo Sánchez, Marta Luisa; Nalda Míguez, Rebeca de; Corrales Castellanos, María Eugenia; Marggi Poullaín, Sonia; González Vázquez, Jesús; Vrakking, Marc J.J.; Bañares Morcillo, Luis; Kornilov, Oleg; Cerullo, G.; Ogilvie, J.; Kärtner, F.; Khalil, M.; Li, R.Ultrashort XUV wavelength-selected pulses obtained with high harmonic generation are used to study the dynamics of molecular cations with state-to-state resolution. We demonstrate this by XUV pump - IR probe experiments on CH3I+ cations and identify both resonant and non-resonant dynamics.Item Threshold Photoelectron Spectroscopy of the CH2I, CHI, and CI Radicals(The Journal of Physical Chemistry A, 2021) Chicharro, David V.; Hrodmarsson, Helgi Rafn; Bouallagui, Aymen; Zanchet, Alexandre; Loison, Jean-Christophe; García, Gustavo A.; García Vela, Alberto; Bañares Morcillo, Luis; Marggi Poullaín, SoniaVUV photoionization of the CHnI radicals (with n = 0, 1, and 2) is investigated by means of synchrotron radiation coupled with a double imaging photoion-photoelectron coincidence spectrometer. Photoionization efficiencies and threshold photoelectron spectra (TPES) for photon energies ranging between 9.2 and 12.0 eV are reported. An adiabatic ionization energy (AIE) of 8.334 ± 0.005 eV is obtained for CH2I, which is in good agreement with previous results [8.333 ± 0.015 eV, Sztáray et al. J. Chem. Phys. 2017, 147, 013944], while for CI an AIE of 8.374 ± 0.005 eV is measured for the first time and a value of ∼8.8 eV is estimated for CHI. Ab initio calculations have been carried out for the ground state of the CH2I radical and for the ground state and excited states of the radical cation CH2I + , including potential energy curves along the C−I coordinate. Franck−Condon factors are calculated for transitions from the CH2I(X̃ 2 B1) ground state of the neutral radical to the ground state and excited states of the radical cation. The TPES measured for the CH2I radical shows several structures that correspond to the photoionization into excited states of the radical cation and are fully assigned on the basis of the calculations. The TPES obtained for the CHI is characterized by a broad structure peaking at 9.335 eV, which could be due to the photoionization from both the singlet and the triplet states and into one or more electronic states of the cation. A vibrational progression is clearly observed in the TPES for the CI radical and a frequency for the C−I stretching mode of 760 ± 60 cm−1 characterizing the CI+ electronic ground state has been extracted.Item Femtosecond predissociation dynamics of ethyl iodide in the B-band(Physical Chemistry Chemical Physics, 2019) Murillo Sánchez, Marta Luisa; Marggi Poullaín, Sonia; Loriot, Vincent; Corrales, Maria Eugenia; Bañares Morcillo, LuisFemtosecond velocity map imaging to disentangle the electronic predissociation of ethyl iodide in the B-band.Item Femtosecond photodissociation dynamics of chloroiodomethane in the first absorption band(Chemical Physics Letters, 2017) Murillo Sánchez, Marta Luisa; Marggi Poullaín, Sonia; González-Vázquez, Jesús; Corrales, Maria Eugenia; Balerdi, Garikoitz; Bañares Morcillo, LuisThe real time photodissociation of chloroiodomethane (CH2ICl) in the first absorption band at 268 nm is reported in comparison with the well-known methyl iodide (CH3I) in order to investigate the halogen-atom substituent effect on the time-resolved photodynamics of halomethanes. Femtosecond velocity map imaging measurements in conjunction with resonance enhanced multiphoton ionization (REMPI) to detect the iodine fragments have been performed to obtain translational energy, angular distributions and the photodissociation reaction times. High level ab initio and on-the-fly trajectory calculations have been carried out to rationalize the experimental results in terms of the excited states involved and the dissociation mechanisms.Item Photodissociation dynamics of bromoiodomethane from the first and second absorption bands. A combined velocity map and slice imaging study(Physical Chemistry Chemical Physics, 2018) Marggi Poullaín, Sonia; Chicharro, David ; Navarro, Eduardo; Rubio-Lago, Luis; González-Vázquez, Jesús; Bañares Morcillo, LuisThe photodissociation dynamics of bromoiodomethane (CH2BrI) have been investigated at the maximum of the first A and second A′ absorption bands, at 266 and 210 nm excitation wavelengths, respectively, using velocity map and slice imaging techniques in combination with a probe detection of both iodine and bromine fragments, I(2P3/2), I*(2P1/2), Br(2P3/2) and Br*(2P1/2) via (2 + 1) resonance enhanced multiphoton ionization. Experimental results, i.e. translational energy and angular distributions, are reported and discussed in conjunction with high level ab initio calculations of potential energy curves and absorption spectra. The results indicate that in the A-band, direct dissociation through the 5A′ excited state leads to the I(2P3/2) channel while I*(2P1/2) atoms are produced via the 5A′ → 4A′/4A′′ nonadiabatic crossing. The presence of Br and Br* fragments upon excitation to the A-band is attributed to indirect dissociation via a curve crossing between the 5A′ with upper excited states such as the 9A′. The A′-band is characterized by a strong photoselectivity leading exclusively to the Br(2P3/2) and Br*(2P1/2) channels, which are likely produced by dissociation through the 9A′ excited state. Avoided crossings between several excited states from both the A and A′ bands entangle however the possible reaction pathways.Item Femtosecond XUV induced dynamics of the methyl iodide cation(2019) Reitsma, Geert; Murillo Sánchez, Marta Luisa; Nalda Míguez, Rebeca de; Corrales Castellanos, María Eugenia; Marggi Poullaín, Sonia; González Vázquez, Jesús; Vrakking, Marc ; Bañares Morcillo, Luis; Kornilov, OlegUltrashort XUV wavelength-selected pulses obtained with high harmonic generation are used to study the dynamics of molecular cations with state-to-state resolution. We demonstrate this by XUV pump - IR probe experiments on CH3I+ cations and identify both resonant and non-resonant dynamics.Item Stark control of multiphoton ionization through Freeman resonances in alkyl iodides(The Journal of Chemical Physics, 2023) Casasús, Ignacio ; Corrales, María ; Murillo Sánchez, Marta Luisa; Marggi Poullaín, Sonia; Oliveira, Nelson de; Limão-Vieira, Paulo; Bañares Morcillo, LuisMultiphoton ionization (MPI) of alkyl iodides (RI, R = CnH2n+1, n = 1–4) has been investigated with femtosecond laser pulses centered at 800 and 400 nm along with photoelectron imaging detection. In addition, the ultraviolet (UV)–vacuum ultraviolet (VUV) absorption spectra of gas-phase RIs have been measured in the photon energy range of 5–11 eV using the VUV Fourier transform spectrometer at the VUV DESIRS beamline of the synchrotron SOLEIL facility. The use of high-laser-field strengths in matter–radiation interaction generates highly non-linear phenomena, such as the Stark shift effect, which distorts the potential energy surfaces of molecules by varying both the energy of electronic and rovibrational states and their ionization energies. The Stark shift can then generate resonances between intermediate states and an integer number of laser photons of a given wavelength, which are commonly known as Freeman resonances. Here, we study how the molecular structure of linear and branched alkyl iodides affects the UV–VUV absorption spectrum, the MPI process, and the generation of Freeman resonances. The obtained results reveal a dominant resonance in the experiments at 800 nm, which counter-intuitively appears at the same photoelectron kinetic energy in the whole alkyl iodide series. The ionization pathways of this resonance strongly involve the 6p( 2 E3/2) Rydberg state with different degrees of vibrational excitation, revealing an energy compensation effect as the R-chain complexity increasesItem A velocity-map imaging study of the photodissociation of the methyl iodide cation(Physical Chemistry Chemical Physics, 2017) Marggi Poullaín, Sonia; Chicharro Vacas, David; Rubio-Lago, Luis; González-Vázquez, Jesús; Bañares Morcillo, LuisThe photodissociation dynamics of the methyl iodide cation has been studied using the velocity map imaging technique. A first laser pulse is used to ionize methyl iodide via a (2 + 1) REMPI scheme through the 5pp - 6p Rydberg state two-photon transition. The produced CH3I+(X) ions are subsequently excited at several wavelengths between 242 and 260 nm. The reported translational energy distributions for the methyl and iodine ions present a Boltzmann-type unstructured distribution at low excitation energies as well as a recoiled narrow structure at higher excitation energies highlighting two different dissociation processes. High level ab initio calculations have been performed in order to obtain a deeper understanding of the photodissociation dynamics of the CH3I+ ion. Direct dissociation on a repulsive state from the manifold of states representing the B˜ excited state leads to CH3+(X) + I*(2P1/2), while the CH3 + I+(3P2) channel is populated through an avoided crossing outside the Franck–Condon region. In contrast, an indirect process involving the transfer of energy from highly excited electronic states to the ground state of the ion is responsible for the observed Boltzmann-type distributions.