10 results on '"Chicharro, David V."'
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2. Imaging the Photodissociation Dynamics and Fragment Alignment of CH2BrI at 193 nm
- Author
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Recio, Pedro, primary, Cachón, Javier, additional, Rubio-Lago, Luis, additional, Chicharro, David V., additional, Zanchet, Alexandre, additional, Limão-Vieira, Paulo, additional, de Oliveira, Nelson, additional, Samartzis, Peter C., additional, Marggi Poullain, Sonia, additional, and Bañares, Luis, additional
- Published
- 2022
- Full Text
- View/download PDF
3. Imaging the Photodissociation Dynamics and Fragment Alignment of CH2BrI at 193 nm
- Author
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Universidad Complutense de Madrid, Ministerio de Ciencia e Innovación (España), Fundación Carolina, Fundación Endesa, Foundation for Research and Technology, European Commission, Consejo Superior de Investigaciones Científicas (España), Recio, Pedro [0000-0002-4867-2872], Limão-Vieira, Paulo [0000-0003-2696-1152], Samartzis, Peter C. [0000-0001-8873-2326], Marggi Poullain, Sonia [0000-0001-6712-3628], Bañares, Luis [0000-0002-0777-2375], Recio, Pedro, Cachón, Javier, Rubio-Lago, Luis, Chicharro, David V., Zanchet, Alexandre, Limão-Vieira, P., de Oliveira, Nelson, Samartzis, Peter C., Marggi Poullain, Sonia, Bañares, Luis, Universidad Complutense de Madrid, Ministerio de Ciencia e Innovación (España), Fundación Carolina, Fundación Endesa, Foundation for Research and Technology, European Commission, Consejo Superior de Investigaciones Científicas (España), Recio, Pedro [0000-0002-4867-2872], Limão-Vieira, Paulo [0000-0003-2696-1152], Samartzis, Peter C. [0000-0001-8873-2326], Marggi Poullain, Sonia [0000-0001-6712-3628], Bañares, Luis [0000-0002-0777-2375], Recio, Pedro, Cachón, Javier, Rubio-Lago, Luis, Chicharro, David V., Zanchet, Alexandre, Limão-Vieira, P., de Oliveira, Nelson, Samartzis, Peter C., Marggi Poullain, Sonia, and Bañares, Luis
- Abstract
The photodissociation dynamics and photofragment alignment of bromoiodomethane (CH2BrI) have been studied at 193 nm using a double experimental and theoretical approach. In addition, the ultraviolet (UV)-vacuum ultraviolet (VUV) absorption spectrum of gas phase CH2BrI has been measured in the photon energy range of 5-11 eV using the VUV Fourier transform spectrometer (FTS) at the VUV beamline DESIRS of the synchrotron SOLEIL facility. The slice imaging technique in combination with resonance enhanced multiphoton ionization (REMPI) detection of the Br(2PJ) and I(2PJ) (with J = 3/2 and 1/2 for Br/I and Br*/I*, respectively) atomic photofragments have been used to produce experimental translational energy and angular distributions, which were analyzed to deliver, on one hand, the partitioning of the available energy among the different degrees-of-freedom of the photofragments and, on the other, the photofragment polarization in terms of aqk(p) alignment parameters. The experimental measurements were rationalized in terms of high-level ab initio calculations of vertical excitation energies, transition dipole moments and potential energy curves (PECs) along different reaction coordinates to provide a complete picture of the photodissociation dynamics. The results indicate that for excitation at 193 nm, prompt C-X cleavage (with X being either halogen atom, Br or I) competes with fast internal conversion and consequent stochastic dissociation in lower electronic states. In the case of the CH2Br + I(2P3/2)/I*(2P1/2) channels, the dynamics are greatly biased toward the stochastic dissociation process due to both the particular PECs landscape and the unfavored excitation of the CH2BrI ensemble with respect to the C-I molecular axis at this excitation energy. The ab initio PECs provide a tentative path for the fast dissociation process in either case. For the C-Br bond breakage, excitation to the 13A' electronic state and predissociation through the 11A'/11A″ or 12A'/12A″ sta
- Published
- 2022
4. Imaging the Photodissociation Dynamics and Fragment Alignment of CH2BrI at 193 nm.
- Author
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Recio, Pedro, Cachón, Javier, Rubio-Lago, Luis, Chicharro, David V., Zanchet, Alexandre, Limão-Vieira, Paulo, de Oliveira, Nelson, Samartzis, Peter C., Marggi Poullain, Sonia, and Bañares, Luis
- Published
- 2022
- Full Text
- View/download PDF
5. Threshold Photoelectron Spectroscopy of the CH2I, CHI, and CI Radicals
- Author
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Chicharro, David V., primary, Hrodmarsson, Helgi Rafn, additional, Bouallagui, Aymen, additional, Zanchet, Alexandre, additional, Loison, Jean-Christophe, additional, García, Gustavo A., additional, García-Vela, Alberto, additional, Bañares, Luis, additional, and Marggi Poullain, Sonia, additional
- Published
- 2021
- Full Text
- View/download PDF
6. Photodissociation Dynamics and Stereodynamics of Methyl Mercaptan and Dimethylsulde from the Second Absorption Band at 201 and 210 nm
- Author
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Chicharro, David V, Marggi Poullain, Sonia, Rubio-Lago, Luis, and Bañares, Luis
- Abstract
The role of promoting and spectator modes vs energy randomization in nonadiabatic dynamics is interrogated in the photodissociation of methyl mercaptan, CH3SH, and dimethyl sulfide, CH3SCH3 or DMS, in the second absorption band. The primary CH3(ν) radicals produced in the dissociation of both systems at 210 nm have been resonantly detected in slice-imaging experiments, and the corresponding translational energy and angular distributions have been obtained. The stereodynamical information provided by Dixon’s bipolar moments in conjunction with the energy partitioning among the different degrees of freedom of the primary CH3(ν) products offers a panoramic picture of the photodissociation process of both systems. The remarkable similitude found between the two systems related to both vector correlations and internal energy content of the corresponding counterparts—SH for methyl mercaptan and SCH3 for DMS—indicates that despite the diabaticity of the process, no efficient energy randomization of the available energy takes place. More specifically, only the parent vibrational modes whose participation in the initial absorption step is imposed by the conical intersection—i.e., the promoting modes—are adiabatically preserved during the process, while the rest of the vibrational modes play the spectator role. The results for both molecules at 210 nm are complemented with experiments carried out for DMS at 201 nm to explore the internal mechanism of the conical intersection in different zones of the absorption region.
- Published
- 2019
7. Photodissociation Dynamics and Stereodynamics of Methyl Mercaptan and Dimethyl Sulfide from the Second Absorption Band at 201 and 210 nm
- Author
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Chicharro, David V., primary, Marggi Poullain, Sonia, additional, Rubio-Lago, Luis, additional, and Bañares, Luis, additional
- Published
- 2019
- Full Text
- View/download PDF
8. Site-specific hydrogen-atom elimination in photoexcited ethyl radical
- Author
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Chicharro, David V., primary, Poullain, Sonia Marggi, additional, Zanchet, Alexandre, additional, Bouallagui, Aymen, additional, García-Vela, Alberto, additional, Senent, María L., additional, Rubio-Lago, Luis, additional, and Bañares, Luis, additional
- Published
- 2019
- Full Text
- View/download PDF
9. Imaging the Photodissociation Dynamics and Fragment Alignment of CH 2 BrI at 193 nm.
- Author
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Recio P, Cachón J, Rubio-Lago L, Chicharro DV, Zanchet A, Limão-Vieira P, de Oliveira N, Samartzis PC, Marggi Poullain S, and Bañares L
- Abstract
The photodissociation dynamics and photofragment alignment of bromoiodomethane (CH
2 BrI) have been studied at 193 nm using a double experimental and theoretical approach. In addition, the ultraviolet (UV)-vacuum ultraviolet (VUV) absorption spectrum of gas phase CH2 BrI has been measured in the photon energy range of 5-11 eV using the VUV Fourier transform spectrometer (FTS) at the VUV beamline DESIRS of the synchrotron SOLEIL facility. The slice imaging technique in combination with resonance enhanced multiphoton ionization (REMPI) detection of the Br(2 PJ ) and I(2 PJ ) (with J = 3/2 and 1/2 for Br/I and Br*/I*, respectively) atomic photofragments have been used to produce experimental translational energy and angular distributions, which were analyzed to deliver, on one hand, the partitioning of the available energy among the different degrees-of-freedom of the photofragments and, on the other, the photofragment polarization in terms of aq k ( p ) alignment parameters. The experimental measurements were rationalized in terms of high-level ab initio calculations of vertical excitation energies, transition dipole moments and potential energy curves (PECs) along different reaction coordinates to provide a complete picture of the photodissociation dynamics. The results indicate that for excitation at 193 nm, prompt C-X cleavage (with X being either halogen atom, Br or I) competes with fast internal conversion and consequent stochastic dissociation in lower electronic states. In the case of the CH2 Br + I(2 P3/2 )/I*(2 P1/2 ) channels, the dynamics are greatly biased toward the stochastic dissociation process due to both the particular PECs landscape and the unfavored excitation of the CH2 BrI ensemble with respect to the C-I molecular axis at this excitation energy. The ab initio PECs provide a tentative path for the fast dissociation process in either case. For the C-Br bond breakage, excitation to the 13 A ' electronic state and predissociation through the 11 A '/11 A″ or 12 A '/12 A″ states, leading to direct dissociation through the 10 A '/9 A ″ states, appear as the most consistent dynamics. For the C-I channel, predissociation does not become a reliable possibility and a fast internal conversion may precede dissociation through the repulsive 6 A '/6 A″ and 4 A '/4 A″ states. The large content of rotational and vibrational excitation of the polyatomic cofragments is justified through the soft impulsive model and the geometrical changes produced along the dissociation pathway. Strikingly, the aq k ( p ) alignment parameters obtained for the Br(2 P3/2 ) and I(2 P3/2 ) photoproducts indicate that the rotational angular momentum of the CH2 X (X = I or Br) cofragment appears highly constrained along the recoil direction. Finally, this work presents a highly plausible explanation for the branching ratio of secondary dissociation processes in the photodynamics of CH2 BrI at 193 nm.- Published
- 2022
- Full Text
- View/download PDF
10. Threshold Photoelectron Spectroscopy of the CH 2 I, CHI, and CI Radicals.
- Author
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Chicharro DV, Hrodmarsson HR, Bouallagui A, Zanchet A, Loison JC, García GA, García-Vela A, Bañares L, and Marggi Poullain S
- Abstract
VUV photoionization of the CH
n I 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 CH2 I, which is in good agreement with previous results [8.333 ± 0.015 eV, Sztáray 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 CH2 I radical and for the ground state and excited states of the radical cation CH2 I+ , including potential energy curves along the C-I coordinate. Franck-Condon factors are calculated for transitions from the CH2 I(X̃2 B1 ) ground state of the neutral radical to the ground state and excited states of the radical cation. The TPES measured for the CH2 I 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.- Published
- 2021
- Full Text
- View/download PDF
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