Person: Bañares Morcillo, Luis
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First Name
Luis
Last Name
Bañares Morcillo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
33 results
Search Results
Now showing 1 - 10 of 33
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 A femtosecond velocity map imaging study on B-band predissociation in CH3I. I. The band origin(The Journal of Chemical Physics, 2010) Gitzinger, Gregory; Corrales Castellanos, María Eugenia; Loriot, Vincent; Amaral Mathon, Gabriel; Nalda Míguez, Rebeca de; Bañares Morcillo, LuisA femtosecond pump-probe experiment, coupled with velocity map ion imaging, is reported on the second absorption band (B-band) of CH3I. The measurements provide a detailed picture of real-time B-band predissociation in the band origin at 201.2 nm. Several new data are reported. (i) A value of 1.5±0.1 ps has been obtained for the lifetime of the excited state, consistent within errors with the only other direct measurement of this quantity [A. P. Baronavski and J. C. Owrutsky, J. Chem. Phys. 108, 3445 (1998)]. (ii) It has been possible to measure the angular character of the transition directly through the observation of fragments appearing early with respect to both predissociation lifetime and molecular rotation. (iii) Vibrational activity in CH3 has been found, both in the umbrella (ν2) and the symmetric stretch (ν1) modes, with estimates of relative populations. All these findings constitute a challenge and a test for much-wanted high level ab initio and dynamics calculations in this energy region.Item Femtosecond Time-Resolved Photofragment Rotational Angular Momentum Alignment in Electronic Predissociation Dynamics(2016) Corrales Castellanos, Maria Eugenia; Shternin, Peter ; Rubio Lago, Luis; Nalda, Rebeca de; Vasyutinskii, Oleg ; Bañares Morcillo, LuisThis Letter presents an experimental and theoretical study of femtosecond time-resolved vector correlations in methyl iodide (CH3I) electronic predissociation via the second absorption B-band at 201.2 nm. The time evolution of the phenomenological anisotropy parameters βl was determined from time-resolved photofragment angular distributions obtained by means of the femtosecond laser pump–probe technique coupled with velocity map imaging detection of vibrational ground-state CH3(ν = 0) fragments and spin–orbit excited I*(2P1/2) atoms. Theoretical interpretation of the experimental results was performed on the basis of a fitting procedure using quasiclassical theory, which elucidates vector correlations in photodissociation of symmetric top molecules. The results of the fitting are in very good agreement with the experimental data and demonstrate the important role of molecular excited-state lifetimes, parent molecule and methyl fragment rotations, and methyl fragment angular momentum alignment on the time-dependent electronic predissociation dynamics.Item A velocity map imaging study of the photodissociation of the à state of ammonia(Physical Chemistry Chemical Physics, 2014) Rodríguez, Javier ; González, Marta ; Rubio-Lago, Luis; Bañares Morcillo, LuisItem 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 A femtosecond velocity map imaging study on B-band predissociation in CH3I. II. The 2_0121 and 3-0131 vibronic levels(The Journal of Chemical Physics, 2012) Gitzinger, Gregory; Corrales, María Eugenia; Loriot, Vincent; Nalda, Rebeca de; Bañares Morcillo, LuisFemtosecond time-resolved velocity map imaging experiments are reported on several vibronic levels of the second absorption band (B-band) of CH3I, including vibrational excitation in the ν2 and ν3 modes of the bound 3R1(E) Rydberg state. Specific predissociation lifetimes have been determined for the 2_01201 and 3_01$301 vibronic levels from measurements of time-resolved I*(2P1/2) and CH3 fragment images, parent decay, and photoelectron images obtained through both resonant and non-resonant multiphoton ionization. The results are compared with our previously reported predissociation lifetime measurements for the band origin 0_0 0 000 [Gitzinger et al., J. Chem. Phys. 132, 234313 (2010)10.1063/1.3455207]. The result, previously reported in the literature, where vibrational excitation to the C-I stretching mode (ν3) of the CH3I 3R1(E) Rydberg state yields a predissociation lifetime about four times slower than that corresponding to the vibrationless state, whereas predissociation is twice faster if the vibrational excitation is to the umbrella mode (ν2), is confirmed in the present experiments. In addition to the specific vibrational state lifetimes, which were found to be 0.85 ± 0.04 ps and 4.34 ± 0.13 ps for the $2_0^1$201 and $3_0^1$301 vibronic levels, respectively, the time evolution of the fragment anisotropy and the vibrational activity of the CH3 fragment are presented. Additional striking results found in the present work are the evidence of ground state I(2P3/2) fragment production when excitation is produced specifically to the 3_0^1 301 vibronic level, which is attributed to predissociation via the A-band 1Q1 potential energy surface, and the indication of a fast adiabatic photodissociation process through the repulsive A-band 3A1(4E) state, after direct absorption to this state, competing with absorption to the 3_0^1 301 vibronic level of the 3R1(E) Rydberg state of the B-band.Item Velocity Map Imaging and Theoretical Study of the Coulomb Explosion of CH3I under Intense Femtosecond IR Pulses(The Journal of Physical Chemistry A, 2011) Corrales Castellanos, María Eugenia; Gitzinger, Gregory; González Vázquez, Jesús; Loriot, Vincent; Nalda Míguez, Rebeca de; Bañares Morcillo, LuisThe Coulomb explosion of CH3Iinanintense(10 100 TW cm 2),ultrashort (50 fs) and nonresonant (804 nm) laserfield has been studied ex-perimentally and justified theoretically. Ion imageshave been recorded using thevelocity map imaging (VMI) technique for different singly and multiply charged ionfragments, CH3p+(p=1)andIq+(qe3), arising from different Coulomb explosionchannels. The fragment kinetic energy distributions obtained from the measuredimages for these ion fragments show significantly lower energies than those expectedconsidering only Coulomb repulsion forces. The experimental results have beenrationalized in terms of one-dimensional wave packet calculations on ab initiopotential energy curves of the different multiply charged species. The calculationsreveal the existence of a potential energy barrier due to a bound minimum in thepotential energy curve of the CH3I2+species and a strong stabilization with respect tothe pure Coulombic repulsion for the higher charged CH3In+(n=3,4)species.Item Strong laser field control of fragment spatial distributions from a photodissociation reaction(2017) Corrales, María ; Nalda, Rebeca de; Bañares Morcillo, LuisAbstract The notion that strong laser light can intervene and modify the dynamical processes of matter has been demonstrated and exploited both in gas and condensed phases. The central objective of laser control schemes has been the modification of branching ratios in chemical processes, under the philosophy that conveniently tailored light can steer the dynamics of a chemical mechanism towards desired targets. Less explored is the role that strong laser control can play on chemical stereodynamics, i.e. the angular distribution of the products of a chemical reaction in space. This work demonstrates for the case of methyl iodide that when a molecular bond breaking process takes place in the presence of an intense infrared laser field, its stereodynamics is profoundly affected, and that the intensity of this laser field can be used as an external knob to control it.Item Wavelength dependence of the multiphoton ionization of CH3I by intense femtosecond laser pulses through Freeman resonances(Physical Chemistry Chemical Physics, 2022) Casasús, Ignacio ; Corrales, María Eugenia; Bañares Morcillo, LuisMultiphoton ionization (MPI) of methyl iodide, CH3I, has been investigated with the photoelectron imaging (PEI) technique, using high intensity femtosecond laser pulses at different central wavelengths.