Introduction to Dissociation Pathways

What is/are Dissociation Pathways?

Dissociation Pathways - An ab initio theoretical method based on the CCSD(T)//B3LYP/6-311g(d,p) level was employed to evaluate the potential energy surface for the dissociation pathways to produce Br2 and BrCl from CHBr2Cl, which encountered a transition state barrier of 445 and 484 kJ mol-1, respectively. ^[1] Except for the X1Σ+, A1Π, and C1Σ+ states, five higher excited 31Σ+, 21Π, 31Π, 41Σ+, and 41Π states are considered in order to investigate the photodissociation pathways in the vacuum ultraviolet region. ^[2] We propose to combine quantum chemical calculations, statistical mechanical methods, and photoionization and particle collision experiments to unravel the redistribution of internal energy of the furan cation and its dissociation pathways. ^[3] For CH3Cl and CH3Br monolayers adsorbed on C6H6, two photodissociation pathways can be identified - neutral photodissociation similar to the gas-phase, and a dissociative electron attachment (DEA) pathway due to photoelectrons from the metal. ^[4] From the phase-dependent behavior of photofragment emission from orientation-selected molecules, dissociation pathways were elucidated experimentally. ^[5] The primary goal was evaluating the dynamical impact of the torsional angle between the NO2 group and the benzene ring plane-something previously implicated in mediating the propensity for branching into different photodissociation pathways (NO vs NO2 elimination). ^[6] Our joint experimental and theoretical findings demonstrate the subtle interplay of steric and electronic factors that determine the size distribution, stability, and dissociation pathways of phosphine ligated gold clusters. ^[7] Both experiment and theory indicate that several isomers are present in the experimental mixture, with different infrared fingerprints as well as dissociation pathways. ^[8] This Concept article introduces the reader to how the pump-probe technique of femtosecond time-resolved mass spectrometry (FTRMS) can overcome this challenge to capture coherent vibrational dynamics on the femtosecond timescale in polyatomic radical cations and enable the analysis of their dissociation pathways. ^[9] Unexpectedly, collisional activation of the complex formed between the peptide and [CoIII(NH3)6]3+ induced gas-phase reduction of the metal to CoII, allowing the peptide to fragment via radical-based dissociation pathways. ^[10] According to our assignment of the NCO internal energy distribution, dominantly bending and a little stretching excited NCO was produced via both dissociation pathways. ^[11] Thanks to a product study, the branching ratio between the two possible photodissociation pathways is also proposed. ^[12] This Concept article introduces the reader to how the pump-probe technique of femtosecond time-resolved mass spectrometry (FTRMS) can overcome this challenge to capture coherent vibrational dynamics on the femtosecond timescale in polyatomic radical cations and enable the analysis of their dissociation pathways. ^[13] For both fundamental interest and understanding clustering and dissociation during electrospray-based propulsion, it is useful to explore the dissociation pathways of protic ionic liquid clusters, as well as the factors affecting the relative contributions of each pathway to the observed MS/MS spectra. ^[14] Although the large oscillator strength of the S2 ← S0 transition results from the (ππ*) excitation of the C═C-C═O backbone, similar to conjugated polyenes, the participation of triplets in the dissociation pathways of acetylacetone appears to have more in common with ketone photochemistry. ^[15] These partially-bound intermediates could lead to distinct, and potentially manipulable, dissociation pathways. ^[16] Losses of CO and/or H2O are the most commonly observed fragmentation channels for [Ce(peptide ? H)]2+ complexes and these dissociation pathways are modeled by DFT calculations. ^[17] The most stable configurations, adsorption energy, and dissociation pathways are calculated thoroughly. ^[18] By measuring yields, kinetic energies, and angular distributions of CH3+ + I+ and CH3+ + I++ ion pairs as a function of the delay between two 25 fs, 790 nm pump and probe pulses, we map both, bound and dissociating nuclear wave packets in intermediate cationic states, thereby tracking different ionization and dissociation pathways. ^[19]

density functional theory

Here, we apply collision-induced dissociation mass spectrometry (CID-MS) to a group of beta-2 agonists to explore characteristic dissociation pathways and we perform complementary density functional theory calculations to better understand the underlying chemistry and the associated theoretical thermodynamics. ^[1] The dissociation pathways of 2,3-DBPC and its potential energy surfaces were calculated using density functional theory. ^[2] The correlation of NO chemisorption with its dissociation pathways on β-MnO2(1 1 0) and (1 0 1) surfaces are investigated based on density functional theory (DFT) with Vienna Ab-initio Simulation Package (VASP). ^[3]

Multiple Dissociation Pathways

First, dPaCS-MD generated multiple dissociation pathways within a reasonable computational time for all the complexes, although the complexes differed significantly in the size of the molecules and in intermolecular interactions. ^[1] The complementary experimental and theoretical investigation provides insight on the photodissociation of CH2OO via multiple dissociation pathways through two regions of CoIn that control the branching and energy distributions of products. ^[2] However, biomolecules with multiple dissociation pathways may have considerably more complicated force dependencies. ^[3] However, biomolecules with multiple dissociation pathways may have considerably more complicated force dependencies. ^[4]

Different Dissociation Pathways

Electron ionization of 2NI leads to analogous fragment cations as in imidazole, yet different dissociation pathways must be operative due to the presence of the NO2 group. ^[1] Different dissociation pathways are collectively induced and their interference contributeto the kinetic energy release spectra. ^[2] The results show that the decomposition of the Criegee intermediate proceeds through different dissociation pathways. ^[3] On the basis of the energetics of the different dissociation pathways and analyses of the observed KER distributions, three-body fragmentation processes are proposed as major contributors to the formation of the observed products. ^[4]

Unimolecular Dissociation Pathways

Quantum chemistry methods were used to calculate the energetics and kinetics of various possible unimolecular dissociation pathways involved in the thermal decomposition of 2-MTHF. ^[1] The calculated energy barriers for all the unimolecular dissociation pathways are higher than 20 and 35 kcal/mol for Ng = Kr and Xe, respectively. ^[2] Recent studies, which focused on the gas phase ion chemistry of this class of anions, revealed several unusual ion-molecule and unimolecular dissociation pathways. ^[3]

Ligand Dissociation Pathways

The simulations also reproduce changes in residence time due to allosteric modulation and reveal associated changes in ligand dissociation pathways. ^[1] The simulations also reproduce changes in residence time due to allosteric modulation and reveal associated changes in ligand dissociation pathways. ^[2] Multiple ligand dissociation pathways were discovered. ^[3]

Dominant Dissociation Pathways

Here, backbone cleavages were the dominant dissociation pathways. ^[1] Losses of CO and glycine are the dominant dissociation pathways for the [b4 – HN CH2]+ ion. ^[2]

Possible Dissociation Pathways

Two possible dissociation pathways of H2O molecule on PuH2 (1 1 0) surface were studied by the climbing-image nudged elastic band (CI-NEB) method. ^[1] In order to analyze the thermochemical stability of these complexes, we have calculated the changes in the related dissociation energies and free energies by considering different possible dissociation pathways (four two-body and one three-body) such as (a) LMCN(/NC) = L + MCN(/NC); (b) LMCN = LM + CN; (c) LMCN = L + M + CN; (d) LMCN = LM+ + CN−; and (e) LMCN = L− + MCN+. ^[2]

Direct Dissociation Pathways

13 eV were discovered, which are energetically more favorable than O2  direct dissociation pathways. ^[1] Besides single-photon dynamics, distinct direct dissociation pathways arising from two-photon pump absorption are also revealed. ^[2]

Two Dissociation Pathways

The bimodal product translational energy and angular distributions indicate two dissociation pathways to the H + C6H10 products in cyclohexyl. ^[1] Based on the first-principles calculations, we demonstrate two dissociation pathways of the NO ligand on the precursor. ^[2]

dissociation pathways may

However, biomolecules with multiple dissociation pathways may have considerably more complicated force dependencies. ^[1] However, biomolecules with multiple dissociation pathways may have considerably more complicated force dependencies. ^[2]

dissociation pathways involved

Quantum chemistry methods were used to calculate the energetics and kinetics of various possible unimolecular dissociation pathways involved in the thermal decomposition of 2-MTHF. ^[1] For these low energy electrons, there can be many different degradation and/or dissociation pathways involved at the molecular level [1]. ^[2]