Double Charge Transfer Process Research Articles

Double charge transfer processes enable a green multiple resonance-induced thermally activated delayed fluorescence emitter for an efficient narrowband OLED.

Benefitting from short-range charge transfer (SR-CT) and through-space charge transfer (TSCT) effects, an efficient green narrowband emitter, BNDCN, was developed. Owing to the synergistic effect of double CT processes, a BNDCN-based organic light-emitting diode showed a high external quantum efficiency of 32.3%.

Nonylphenol photodegradation by novel ternary MIL-100(Fe)/ZnFe2O4/PCN composite under visible light irradiation via double charge transfer process

Nonylphenol (NP) residues, as a typical endocrine disrupting chemical (EDC), frequently exist in sewage, surface water, groundwater and even drinking water, which poses a serious threat to human health due to its bioaccumulation. In order to remove NP, a series of MIL-100(Fe)/ZnFe2O4/flake-like porous carbon nitride (MIL/ZC) was synthesized through in-situ synthesis at room temperature. High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation. The results show that 30MIL/ZC2 (20 wt.% ZnFe2O4) ternary composite had the best photocatalytic activity (99.84%) when the dosage was 30 mg. Further mechanism analysis shows that the excellent photocatalytic activity of 30MIL/ZC2 could be ascribed to the double charge transfer process between flake-like porous carbon nitride (PCN) and other catalysts in the ternary heterojunction, and the separation of photogenerated electron-hole pairs was more effective. In addition, the 30MIL/ZC2 also showed high stability after five cycles of the photodegradation reaction. Furthermore, the active substance (•O2−) was considered to be the main active substance in the NP degradation process. Based on the research results, the possible photocatalytic reaction mechanism of 30MIL/ZC2 ternary composite was proposed and discussed in detail.

Novel ternary BiOI/g-C3N4/CeO2 catalysts for enhanced photocatalytic degradation of tetracycline under visible-light radiation via double charge transfer process

In this work, a novel visible-light-driven ternary BiOI/g-C3N4/CeO2 photocatalyst was successfully synthesized by calcination and hydrothermal treatment. The obtained ternary BiOI/g-C3N4/CeO2 had high photocatalytic performance for the degradation of tetracycline (TC) under visible-light irradiation. The samples were characterized by X-ray diffraction (XRD), UV–Vis diffuse reflectance (DRS) spectroscopy, and Fourier transform infrared spectroscopy (FT-IR), etc. The results indicated that 3 wt% BiOI/g-C3N4/CeO2 catalyst possessed the best photocatalytic activity (91.6%) among all the as-prepared samples. The enhanced photocatalytic activity could be attributed to a double charge transfer process between g-C3N4 and other catalysts in the ternary heterojunction, so that the separation of photogenerated electron–hole pairs was more effective. The as-prepared ternary sample also exhibited high stability after six cycles of the photodegradation reaction. Additionally, the active species (h+) were considered as the main reactive species during the degradation of TC. Based on the research results, a possible photocatalytic reaction mechanism for the BiOI/g-C3N4/CeO2 sample was proposed and discussed in detail.

Experimental investigation of the reaction window in double charge transfer process involving biomolecule target FeTPPCl

In the study of ion induced fragmentation of gas phase biomolecule FeTPPCl, a reaction window was experimentally determined. The populations of individual fragmentation channels of parent dications FeTPPCl2+ were found to be modulated by such a reaction window. A shift to lower energy was observed using projectile ions H+ comparing to the case of F+ impact.

Double charge transfer spectroscopy of acetylene dication C 2H 22+ at vibrational resolution

We have observed a vibrational progression of C 2H 2 2+ with double charge transfer (DCT) spectroscopy. From an exploratory calculation, the progression is assigned to the symmetric C–C stretching mode of the lowest singlet 1Δ g state with linear geometry. The observed structure is well reproduced with the theoretical Franck–Condon (FC) factors obtained from the potential curves of the 1Δ g and first-excited 1Σ g + states along the normal C–C stretching coordinate. Multi-reference CI calculations reveal a predominant contribution of the 1Δ g state. These results suggest that the DCT process can probe dicationic states of polyatomic molecules like acetylene with resort to the FC principle.

Double charge transfer spectroscopy for N 22+ and CO 2+ at vibrational resolution

Doubly charged molecular ions (dications) of N 2 and CO have been studied using a double charge transfer (DCT) spectrometer capable of resolving vibrational levels. The vibrational structures of low-lying singlet states are observed in the translational energy spectra of H − ions produced by double electron capture collisions of H + projectiles. The observed spectra are well reproduced using the theoretical Franck–Condon (FC) profiles calculated from the best available ab initio potential curves. This suggests that the DCT process obeys the FC principle, i.e., the vertical transition from a neutral molecule to the corresponding dication.

Measurement of helium lines in the edge plasma of the JIPP T-IIU tokamak

UV-visible spectra of neutral and low-ionized impurities are observed in the edge plasma of the JIPP T-IIU tokamak. To study recombination processes, helium was introduced into the deuterium plasma as a trace element. The line intensities of He I from the n = 3, 4, 5 levels were compared with a calculation of the collisional radiative (CR) model. The line intensity distributions were deviated from the CR model, particularly for the lines from n = 3. It seems that the double charge transfer process is one of the dominant recombination processes for He in the edge plasma.

A neutralization-reionization study of C 2H 2+. and H +

A hybrid mass spectrometer of BEQQ geometry (B, magnetic sector; E, electric sector; QQ, quadrupole collision cell with radio-frequency only and quadrupole mass filter), equipped with dual collision cells and a deflector electrode in the field-free region between B and E, has been designed for the study of fundamental and applied studies in gaseous ion chemistry. Characterization of the dual collision cells assembly with interposed deflector is reported here using, principally, ions derived from acetylene. Charge transfer and collisional dissociative processes occurring in the collision cells were investigated using Xe, N 2 and O 2 as neutralization agents and He, N 2 and O 2 as reionization agents. Collisionally induced dissociative ionization (CIDI) of neutral C 2H 2 produced in unimolecular dissociation is compared with the neutralization-reionization (NR) of C 2H 2 +.. The efficiency of the NR processes has been determined for C 2H 2 +. and its fragment ions under single-collision conditions with Xe and O 2 as neutralization and reionization agents, respectively. The effects of positive and negative potentials applied to the downstream isolatable collision cell upon emergent ion signal intensity and degree of dissociation of projectile ions have been investigated. Operation of the dual collision cells assembly is reported for distinguishing between singly and doubly charged ions of the same mass-to-charge ratio, and for distinguishing between competing reaction pathways of doubly charged ions. The separation of single charge transfer (SCT) processes from combined SCT and double charge transfer (DCT) processes in charge reversal is explored, using the dual collision cells filled with a common target gas as a pseudo-single cell. In this application, the deflector electrode permits the observation of negative ions produced solely in SCT processes. Alternatively, with the deflector grounded and a negative potential applied to the downstream collision cell, the collisional processes occurring in each collision cell can be distinguished due to energy separation. Three sets of ion signals are obtained which arise from (1) single and double charge transfer processes in the upstream collision cell, (2) single charge transfer processes only in each of the two collision cells, and (3) single and double charge transfer processes in the downstream collision cell. Evidence obtained by translational energy loss spectroscopy, though of poor resolution, indicates the reionization of fast C 2H 2 to C 2H 2 2+ in two consecutive SCT processes with oxygen as the target gas and, in a separate experiment, the neutralization of C 2H 2 2+ by DCT with Xe as the target gas. In the neutralization of fast atomic and molecular ions, neutral species in high-energy Rydberg states may be formed. Field ionization of Rydberg states of Ar, Kr, and C 2H 2 is reported here, using ionizing fields generated with the application of a potential to the deflector electrode.

A quantal study of differential cross sections for double charge transfer in C4+-He collisions

Differential cross section for the double charge transfer process in C4+-He collisions are studied using a quantal two-channel molecular orbital close coupling expansion method. The calculated results for C4+ at incident energies of 1520 and 500 eV are found to be in good agreement with recent measurements. It is also shown that the quantal calculations and the experimental results are well reproduced by a semiclassical approximation. Comparison with the recent semi-empirical study of the same system by Barany et al. (1986) is also discussed.

Translational energy spectrum of O2-ions formed by 4 keV O2+ions impacting on argon

The translational energy spectrum of O2- arising from single and double collision double charge transfer between 4 keV O2+ ions and Ar atoms has been recorded. The incident O2+ ions are found to be either in the ground x2 Pi g state or in the metastable a4 Pi u state. The single-collision double charge transfer is observed only from metastable O2+ ions, ground state O2+ leading to autodetaching levels of O2-. This result gives evidence on the validity of Franck-Condon principle for molecular transitions occurring in double charge transfer processes.