Dissociative States Research Articles

Threshold-ion-pair-production spectroscopy of H2S and D2S

The threshold-ion-pair-production (TIPP) spectra of H2S and D2S have been recorded in the vicinity of the and thresholds using a tunable vacuum-ultraviolet laser and cold molecular samples () in supersonic expansions. The ion-pair-production signal was found to be much stronger at the thresholds than at the thresholds. From the rotational structure of the spectra, the dominant photodissociation partial waves are determined to be those with , which indicates that dissociative Rydberg states of H2S with a linear ion core are involved in the formation of the ion-pair states. The H + +SH − ion-pair-dissociation threshold energy we derive for H2S is in excellent agreement with the value reported in an earlier TIPP-spectroscopic investigation by Shiell et al. [J. Phys. Chem. A 104 (19), 4339–4342 (2000)]. From our new values of the ion-pair-dissociation thresholds, we determine improved bond-dissociation energies and of and , respectively, where the numbers in parentheses represent an uncertainty of in units of the last digit.

Observation of rotationally dependent fine-structure branching ratios near the predissociation threshold N(2D5/2,3/2) + N(2D5/2,3/2) of 14N2.

Photofragment spin-orbit fine-structure branching ratios have long been predicted to depend on the rotational quantum number J' by theory near the dissociation thresholds of several diatomic molecules, while this has rarely been observed in any photodissociation experiments yet. Here, we measured the fine-structure branching ratios N(2D5/2)/N(2D3/2) produced in the N(2D5/2,3/2) + N(2D5/2,3/2) channel at the b'1Σu +(v = 20) state of 14N2 by using our vacuum ultraviolet (VUV)-pump-VUV-probe time-sliced velocity-mapped ion imaging setup. It is found that 14N2 almost exclusively dissociates into the spin-orbit channel N(2D5/2) + N(2D3/2) at low rotational levels and gradually approaches the statistical or diabatic limit by distributing all possible spin-orbit channels at higher rotational levels. The strongly rotationally dependent fine-structure branching ratios should be due to the increasing strength of nonadiabatic Coriolis interaction among various dissociative states in the so-called "recoupling zone" as J' increases. They are supposed to provide unprecedented information on the near threshold photodissociation dynamics of 14N2.

Dissociative Ionization and Coulomb Explosion of CHBrCl2 in Intense Near-Infrared Femtosecond Laser Fields

We experimentally demonstrate the dissociative photoionization of CHBrCl2 molecules in a femtosecond laser field by time-of-flight mass spectrum and dc-slice imaging technology. The results suggest that the low kinetic energy components are from the dissociative ionization process of single-charged molecular ions. The angular distribution of fragment Cl+ ions can be attributed to the features of dissociative state and molecular configuration, and that of Br+ ions results from the electronic wave-packet evolution and combination of the multi-dissociation processes. The high kinetic energy components are from the Coulomb explosion of multi-charged molecular ions, and the error of the C-Br distance involved in the Coulomb explosion can be explained by the movement of the effective charge center of the polyatomic molecule.

Near-exact treatment of seniority-zero ground and excited states with a Richardson-Gaudin mean-field.

Eigenvectors of the reduced Bardeen-Cooper-Schrieffer (BCS) Hamiltonian, Richardson-Gaudin (RG) states, are used as a variational wavefunction ansatz for strongly correlated electronic systems. These states are geminal products whose coefficients are solutions of non-linear equations. Previous results showed an un-physical apparent avoided crossing in ground state dissociation curves for hydrogen chains. In this paper, it is shown that each seniority-zero state of the molecular Coulomb Hamiltonian corresponds directly to an RG state. However, the seniority-zero ground state does not correspond to the ground state of a reduced BCS Hamiltonian. The difficulty is in choosing the correct RG state. The systems studied showed a clear choice, and we expect that it should always be possible to reason physically which state to choose.

Role of Exciton Diffusion and Lifetime in Organic Solar Cells with a Low Energy Offset.

Despite general agreement that the generation of free charges in organic solar cells is driven by an energetic offset, power conversion efficiencies have been improved using low-offset blends. In this work, we explore the interconnected roles that exciton diffusion and lifetime play in the charge generation process under various energetic offsets. A detailed balance approach is used to develop an analytic framework for exciton dissociation and free-charge generation accounting for exciton diffusion to and dissociation at the donor–acceptor interface. For low-offset systems, we find the exciton lifetime to be a pivotal component in the charge generation process, as it influences both the exciton and CT state dissociation. These findings suggest that any novel low-offset material combination must have long diffusion lengths with long exciton lifetimes to achieve optimum charge generation yields.

Investigation of the elution behavior of dissociating itaconic acid on a hydrophobic polymeric adsorbent using in-line Raman spectroscopy

The use of adsorption for the purification of dicarboxylic acids is rather limited and currently predominantly confined to ion-exchange chromatography. A promising, but less regarded alternative is the use of hydrophobic adsorbents. Regarding hydrophobic absorbents, the literature focuses on screenings of adsorbents for purification of (di)carboxylic acids with regard to adsorption equilibria. The investigation of dynamic phenomena in the column received only minor attention. In this contribution, this knowledge gap is addressed. First, the adsorption behavior of itaconic acid species on the hydrophobic, highly-crosslinked polymeric adsorbent Chromalite™ PCG1200C is investigated. For this purpose, adsorption isotherms are determined via frontal analysis at pH values of 2, 3, 4.5, 6.5, and 8 to evaluate the dependency of the adsorption capacity on the dissociation state. Capacities above 150 g Lads−1 at liquid phase concentrations of 70 g L−1 are observed at a pH of 2. A strong decrease of capacity with increasing pH value, i.e., with increasing fraction of dissociated negatively charged acid species, is observed. Second, pulse experiments at aforementioned pH values are performed. Thereby, in-line Raman spectra are recorded at the column outlet, which allows the direct differentiation of the acid species state of dissociation. The spectral information is evaluated for quantitative concentration profiles of itaconic acid species using Indirect Hard Modeling with mixture hard models that are calibrated subject to ideal as well as non-ideal thermodynamics. In-line measurement errors of ≤ 3.5 g L−1 are achieved for the itaconic acid species. In dependency of the pH of the feed solution, a separation of the individual acid species within the pulse experiments is observed. It is conjectured that the process is dominated by a superposition of species-dependent adsorption characteristics and dissociation reactions.

Entropic force and real-time dynamics of holographic quarkonium in a magnetic field

We continue the study of a recently constructed holographic QCD model supplemented with magnetic field. We consider the holographic dual of a quark, anti-quark pair and investigate its entropy beyond the deconfinement phase transition in terms of interquark distance, temperature and magnetic field. We obtain a clear magnetic field dependence in the strongly decreasing entropy near deconfinement and in the entropy variation for growing interquark separation. We uncover various supporting evidences for inverse magnetic catalysis. The emergent entropic force is found to become stronger with magnetic field, promoting the quarkonium dissociation. We also probe the dynamical dissociation of the quarkonium state, finding a faster dissociation with magnetic field. At least the static predictions should become amenable to a qualitative comparison with future lattice data.

Plasma-relevant fast electron impact study of trifluoromethane

Abstract Trifluoromethane is an important etching gas in semiconductor industries as the fluorine source in reactive etching plasma. Electron impact excitations into the dissociation states are essential for plasma modeling. By employing an angle-resolved electron energy loss spectrometer, the generalized oscillator strengths (GOSs) for the valence-shell excited states have been determined at an absolute scale utilizing the crossed-beam based relative flow technique. The measurement was performed with an incident electron energy of 1500 eV at an energy resolution of about 70 meV. The corresponding optical oscillator strengths are also obtained by extrapolating the measured GOSs to the limit of zero momentum transfer. The extrapolated data and fitted linewidths are used to reproduce the photoabsorption spectra and compare with the available experimental and theoretical results. In addition, the integral cross sections from the excitation threshold to 5000 eV of the associated excited states have been derived by using the BE-scaling method. The resulted data can not only be used in plasma models but also serve as a benchmark for further theoretical calculations.

Search for Decays of the 9B Nucleus and Hoyle State in 14N Nucleus Dissociation

First results of an analysis to determine contribution of decays of the unstable $^{8}$Be and $^{9}$B nuclei and the Hoyle 3$\alpha$-state to dissociation of $^{14}$N $\to$ 3He (+H) are presented. As the research material, layers of nuclear track emulsion longitudinally exposed to 2.9 $A$ GeV/$c$ $^{14}$N nuclei with at the JINR Nuclotron. Under the assumption that the He and H fragments retain momentum per nucleon of the primary nucleus, these unstable states are identified by the invariant mass calculated from the emission angles of the fragments.

Correlation between molecular configuration and charge transfer dynamics in highly efficient organic solar cells

Molecular design and charge transport dynamics play an important role in achieving highly efficient organic solar cells (OSCs). In this work, non-fullerene acceptor Y6, its alkyl chain modified derivative N3 and halogen-replaced derivative BTP-BO-4Cl are selected to fabricate OSCs. The OSCs obtain a high power conversion efficiency (PCE) of 16.86%. The impact of different modification methods on molecular configuration and energy level matching is investigated systematically by time-resolved photoluminescence (TRPL) and transient absorption spectroscopy (TAS). The results demonstrate that side chain modification has a positive effect on molecular layer spacing, domain area size and charge carrier mobilities. More importantly, halogen atom replacing has the similar but more positive impact, bringing a higher PCE than side chain modification. The overall processes of charge generation, dissociation and recombination in OSCs are studied systematically for the first time. For the best-performance device, the lifetimes of singlet exciton recombination (τ1), charge transfer (CT) state recombination (τ2), singlet exciton dissociation (τ3) and CT state dissociation (τ4) are calculated as ∼500 ps, ∼2 ns, ∼200 fs and ∼1 ps, respectively. The correlation between molecular configuration and charge transfer dynamics is established, which can provide a guideline for designing materials of highly efficient OSCs.

Case Report: REL-1017 Reduces Abnormal Clinician Administered Dissociative States Scale Scores in Patients with Major Depressive Disorder

Dissociative symptoms may be found in a subset of patients with major depressive disorders (MDD). The Clinician-Administered Dissociative States Scale (CADSS) is a 23-item scale for the measurement of present-state dissociative symptoms with good inter-rater reliability and construct validity that can discriminate patients with dissociative disorders. The total CADSS score is derived by adding the score for each of the 23 items. A score of 4 or more on the CADSS is considered abnormal and clinically meaningful. Uncompetitive N-methyl-d-aspartic acid receptor (NMDAR) channel blockers have been proposed as a treatment for post-traumatic stress disorder (PTSD). REL-1017 is a novel, low potency, NMDAR channel blocker currently in Phase 3 studies for MDD. This retrospective case series describes a subset of patients from a double-blind, randomized, placebo-controlled, in-patient 7-day, phase 2 trial of oral, once daily, 25mg (75mg loading dose on day 1, first dose) and 50mg REL-1017 (100mg loading dose on day 1, first dose) as an adjunctive treatment for MDD. This subset of patients was selected based on abnormal CADSS score at baseline, pre-treatment with the study drug. As part of REL-1017 safety evaluation, the CADSS was administered at four timepoints to all study patients: (a) 30 to 60minutes pre-treatment at baseline on day 1; (b) 2hours post-treatment on day 1 (after the first dose of study drug); (c) 2hours post-treatment on day 7 (after the last dose); and (d) prior to discharge on day 9 (2days after the last dose). Among the 62 randomized patients, four patients had a CADSS score of at least 4 on day 1 before study drug administration (2 patients in the 25mg arm [CADSS score 22 and 4]; 1 patient in the 50mg arm [CADSS score 35]; 1 patient in the placebo arm [CADSS score 6]). Among these 4 patients, starting on day 1, 2hours post-treatment, the 2 subjects in the 25mg subgroup (75mg loading dose) and 1 subject in the 50mg subgroup (100mg loading dose) showed a clinically meaningful decrease in their CADSS score, while the single patient in the placebo group showed no change. CADSS scores on Day 1 pre-treatment, day 1 post-treatment, day 7 post last treatment, and on day 9 prior to discharge were 22-2-6-0; 4-0-0-0; 35-14-9-0, and 6-6-n/a-n/a, for the two patients in the 25mg REL-1017 subgroup, the single patient in the 50mg REL-1017 subgroup, and the single patient in the placebo group, respectively. These retrospective case report data potentially signal that REL-1017 may determine rapid and sustained improvement in patients with MDD and concurrent clinically meaningful dissociative symptoms assessed by a CADSS score of 4 or above. Ongoing phase 3 trials with REL-1017 are expected to enroll a total of 1200 outpatients with MDD. These studies will potentially generate additional data that may support the initiation of controlled studies with REL-1017 for the treatment of PTSD. Relmada Therapeutics.

Pharmacological modelling of dissociation and psychosis: an evaluation of the Clinician Administered Dissociative States Scale and Psychotomimetic States Inventory during nitrous oxide (‘laughing gas’)-induced anomalous states

RationaleA significant obstacle to an improved understanding of pathological dissociative and psychosis-like states is the lack of readily implemented pharmacological models of these experiences. Ketamine has dissociative and psychotomimetic effects but can be difficult to use outside of medical and clinical-research facilities. Alternatively, nitrous oxide (N2O) — like ketamine, a dissociative anaesthetic and NMDAR antagonist — has numerous properties that make it an attractive alternative for modelling dissociation and psychosis. However, development and testing of such pharmacological models relies on well-characterized measurement instruments.ObjectivesTo examine the factor structures of the Clinician Administered Dissociative States Scale (CADSS) and Psychotomimetic States Inventory (PSI) administered during N2O inhalation in healthy volunteers.MethodsSecondary analyses of data pooled from three previous N2O studies with healthy volunteers.ResultsEffect sizes for N2O-induced dissociation and psychotomimesis were comparable to effects reported in experimental studies with sub-anaesthetic ketamine in healthy volunteers. Although, like ketamine, a three-factor representation of N2O-induced dissociation was confirmed, and a more parsimonious two-factor model might be more appropriate. Bayesian exploratory factor analysis suggested that N2O-induced psychosis-like symptoms were adequately represented by two negative and two positive symptom factors. Hierarchical cluster analysis indicated minimal item overlap between the CADSS and PSI.ConclusionN2O and ketamine produce psychometrically similar dissociative states, although parallels in their psychosis-like effects remain to be determined. The CADSS and PSI tap largely non-overlapping experiences under N2O and we propose the use of both measures (or similar instruments) to comprehensively assess anomalous subjective states produced by dissociative NMDAR antagonists.

An embodied spiritual inquiry into the nature of human boundaries: Outcomes of a participatory approach to transpersonal education and research.

Embodied spiritual inquiry (ESI) is a radical approach to integral and transpersonal education and research offered as a graduate course at the California Institute of Integral Studies (CIIS). Inspired by elements of participatory research and cooperative inquiry, ESI applies interactive embodied meditations to access multiple ways of knowing (e.g., somatic, vital, emotional, mental, contemplative) and mindfully inquire into collaboratively decided questions. This article presents the learning outcomes of an inquiry into the nature of human boundaries within and between co-inquirers, providing an example of how ESI is implemented in the classroom and can be used to study transpersonal subject matter. In particular, the study found that boundaries were experienced in terms of their dynamic effects rather than as static qualities, with a relationship between dissociation and overly firm boundaries, as well as a relationship between integration/merging and more varied combinations of firm and permeable boundaries. Other notable inquiry outcomes include the identification of (a) experiential qualities of the states of dissociation, merging, and integration; (b) a recursive relationship between fear and trust in the modulation of optimal interpersonal boundaries; and (c) the phenomenon of shared emergent experience between practitioners, which suggests the existence of an intersubjective transpersonal field.

Photoinduced bond oscillations in ironpentacarbonyl give delayed synchronous bursts of carbonmonoxide release

Early excited state dynamics in the photodissociation of transition metal carbonyls determines the chemical nature of short-lived catalytically active reaction intermediates. However, time-resolved experiments have not yet revealed mechanistic details in the sub-picosecond regime. Hence, in this study the photoexcitation of ironpentacarbonyl Fe(CO)5 is simulated with semi-classical excited state molecular dynamics. We find that the bright metal-to-ligand charge-transfer (MLCT) transition induces synchronous Fe-C oscillations in the trigonal bipyramidal complex leading to periodically reoccurring release of predominantly axial CO. Metaphorically the photoactivated Fe(CO)5 acts as a CO geyser, as a result of dynamics in the potential energy landscape of the axial Fe-C distances and non-adiabatic transitions between manifolds of bound MLCT and dissociative metal-centered (MC) excited states. The predominant release of axial CO ligands and delayed release of equatorial CO ligands are explained in a unified mechanism based on the σ*(Fe-C) anti-bonding character of the receiving orbital in the dissociative MC states.

Past and Future Explanations for Depersonalization and Derealization Disorder: A Role for Predictive Coding.

Depersonalization (DP) and derealization (DR) refer to states of dissociation in which one feels a sense of alienation in relation to one’s self and environment, respectively. Whilst transient episodes often diminish without treatment, chronic experiences of DP and DR may last for years, with common treatments lacking a strong evidence base for their efficacy. We propose a theoretical explanation of DP and DR based on interoceptive predictive coding, and discuss how transient experiences of DP and DR may be induced in the non-clinical population using virtual reality. Further, we review the use of heartbeat evoked potentials in detecting the neural correlates of DP and DR allowing for an objective measure of these experiences in the non-clinical population. Finally, we discuss how the induction and detection of transient experiences of DP and DR in the non-clinical population could shed light on how the brain constructs one’s sense of self and reality.

Significant role of spin-triplet state for exciton dissociation in organic solids.

Clarification of the role of the spin state that initiates exciton dissociation is critical to attaining a fundamental understanding of the mechanism of organic photovoltaics. Although an excited spin-triplet state with an energy lower than that of excited spin-singlet state is disadvantageous in exciton dissociation, a small electron exchange integral results in small singlet-triplet energy splitting in some material systems. This energy splitting leads to a nearly isoenergetic alignment of both excited states, raising a question about the role of excited spin states in exciton dissociation. Herein, we show that the spin-triplet rather than the spin-singlet plays a critical role in the exciton dissociation that leads to the formation of free carriers. This result indicates that the spin-triplet inherently acts as an intermediate, leading to exciton dissociation. Thus, our demonstration provides a fundamental understanding of the role of excited spin states of organic molecular systems in photoinduced charge-carrier generation.

Theoretical Study of Complex Aspirin and Hydroxypropyl-β-cyclodextrin in Solvent Phase

We estimate the configuration of complex ASA/HPCD in the gas phase by using PM3 and B3LYP methods. Some physical properties in the gas phase, such as complexation energy, deformation energy, dipole moment, etc., are calculated by using PM3 and B3LYP methods. We investigate the dependence of physical properties such as complexation energy, etc., on solvation by using PM3 and B3LYP methods with the PCM method. Complex ASA/HPCD becomes more stable than the dissociation state. The present results suggest that the effect of solvent can be increasing the energy complexation, LUMO energy, HOMO energy, HOMO-LUMO gap energy, electronic potential, and chemical hardness, whereas the electrophilicity decrease.

Theoretical Study of Dissociation Process of Plastocyanins by PaCS-MD Simulation

We present a procedure of calculation of free energy landscape of two proteins by using parallel cascade molecular dynamics (PaCS-MD) and multiple independent umbrella sampling (MIUS). The free energy landscape of two plastocyanins for association/dissociation process is investigate by using the present method. We find that binding free energy is around 1 kcal/mol and that the barrier energy at around the middle range between the equilibrium point and the dissociation state becomes about 1 kcal/mol from the association process. The present results suggest that the energy barrier may arise from hydrogen bonds between two plastocyanins. We also find that the effective interaction between two plastocyanins already vanishes at the distance of 2 Å from equilibrium state. The equilibrium point of the complex around 27.9 Å is a good agreement with the experimental result 27.8 Å

Decarboxylation efficiency of carboxylic acids as ligands of metal oxide nanocluster resists upon γ-ray irradiation

Metal oxide nanocluster resists have recently attracted considerable attention for use in extreme ultraviolet lithography. To obtain sophisticated guidelines for material design, it is necessary to understand well the radiation-induced chemical reaction scheme including the insolubilization mechanism. In this study, the production of CO2, which is considered to be one of the end products of treatment with an ionizing radiation, was investigated for eight types of carboxylic acid under various conditions using γ-rays (60Co) as a radiation source. The amount of CO2 produced was measured by gas chromatography. G CO2 (/100 eV), which indicates decarboxylation efficiency, was evaluated. CO2 was generated through electron addition, hole transfer, and hydroxyl radical addition to the molecular and ionic forms of carboxylic acids. The dependences of G CO2 on reaction partners were clarified. The dependences of G CO2 on the molecular structure and dissociative state of carboxylic acids were also clarified.

A combined infrared spectroscopy and density functional theory study of the [formula omitted] and [formula omitted] reaction on [formula omitted

In this work we performed a combined infrared spectroscopy and density functional theory (DFT) study of the oxidation reaction of methane on Cr2O3. We found that adsorbed oxygen in a dissociative state favors the dehydrogenation of CH4. The reaction occurs with the formation of both methoxy species with surface oxygen atoms and hydroxyl with the adsorbed oxygen atoms. The oxidation of the methoxy species leads to the formation of adsorbed formaldehyde, which can transform into the surface dioxymethylene species. The interaction of adsorbed CH3 with hydroxyl can also produce methanol, which in turn can react with dioxymethylene or formate species.