The laser induced predissociation dynamics of the B Rydberg state of CH(3)I following two-photon absorption of a pump pulse was studied with femtosecond pump-probe photoelectron imaging coupled with time-resolved mass spectroscopy. The predissociation lifetime was measured to be 1.55 ps induced by the crossing between the B state and the repulsive A-band. Two possible predissociation channels were observed originating from (a) direct coupling between the B state and the repulsive (3)Q(0) state and (b) a second crossing between the (3)Q(0) and (1)Q(1) states after the coupling between the B and (3)Q(0) states, respectively.
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http://dx.doi.org/10.1364/oe.17.010506 | DOI Listing |
J Chem Phys
December 2024
Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
Photodissociation of the CH2Cl radical is investigated by using high-level multireference configuration interaction ab initio methods, including the spin-orbit coupling. All possible fragmentation pathways, namely, CH2Cl + hν → CH2 + Cl, HCCl + H, and CCl + H2, have been analyzed. The potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distance of each pathway have been calculated.
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry Chinese Academy of Sciences, Beijing 100190, China.
The dicarbon molecule, C, is one of the most important diatomic species in various gaseous environments. Despite extensive spectroscopic studies in the last two centuries, the radiative and photodissociative properties of C in its highly excited electronic states are still largely unexplored, particularly in the short vacuum ultraviolet (VUV) region. In this study, the lifetimes of C for rotational levels in the recently identified 1Σ state up to the vibrational level ν' = 4 and in the Σ state up to ν' = 2 are measured for the first time with a VUV-pump-UV-probe photoionization scheme.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
Department of Chemistry, The College of William & Mary, Williamsburg, VA 23187-8795, USA.
The topology of multidimensional potential energy surfaces defines the bimolecular collision outcomes of open-shell radicals with molecular partners. Understanding these surfaces is crucial for predicting the inelastic scattering and chemical transformations of increasingly complex radical-molecule collisions. To characterize the inelastic scattering mechanisms of nitric oxide (NO) radicals with large alkanes, we generated the collision complexes comprised of NO with propane or -butane.
View Article and Find Full Text PDFJ Phys Chem A
September 2024
State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
The first high-resolution translational spectroscopy studies of D atom photoproducts following excitation to the Rydberg states of DS are reported. Excitation at wavelengths λ ∼ 139.1 nm reveals an unusual 'inverse' isotope effect; the B(3←2) Rydberg state of DS predissociates much faster than its counterpart in HS.
View Article and Find Full Text PDFFaraday Discuss
August 2024
Department of Chemistry, The College of William & Mary, Williamsburg, VA 23187-8795, USA.
In bimolecular collisions between open-shell radicals and increasingly-larger alkanes, the relative impact configurations open the possibility of reactive and nonreactive outcomes that are isomer specific. To model the interaction potential between molecular scattering partners, observables are needed from experiments that can quantify both the initial molecular orientations and internal energies on multidimensional potential energy surfaces. Recent work by our group demonstrated that upon infrared (IR) excitation, the dynamics of the nitric oxide-methane collision complex (NO-CH) are dependent on the initial monomer geometries, as small changes in configuration substantially affect the energies, electronic couplings, and predissociation pathways due to the Jahn-Teller effect.
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