Theoretical study of generalized oscillator strengths for the low-lying electronic excitations of CH3Cl and CF3Cl

We report a theoretical study of electronic excitation in CH3Cl and CF3Cl by electron impact. Momentum-transfer-dependent generalized oscillator strengths (GOSs) are calculated for transitions to low-lying excited singlet-states at the equation-of-motion coupled-cluster singles and doubles level. The influence of molecular vibration is taken into account in the calculation. The theoretical results show reasonable overall agreement with experimental data reported in the literature. The shapes of the GOS profiles reveal that the 1 1E state of CH3Cl has a valence-Rydberg mixed nature, while that of CF3Cl is of a predominant C-Cl antibonding character. A comparison with the experimental GOSs of CH3Cl provides unambiguous evidence that the 3pe state is lower in energy than the 3pa1 state. Optical oscillator strengths are also calculated and comparison is made with available experimental and other theoretical results.

Multi-Conformational Luminescence and Phosphorescence of Few Phenazine 1,2,3-Triazole Molecules

Dropcast films produced from blends solutions of phenazine 1,2,3-triazole molecules in very low concentrations in a 1,3-Bis (N-carbazolyl) benzene (mCP) matrix were investigated at room temperature. The mCP acts as an optically inert matrix, having no influence on the emission properties of the guest molecules. Its conductive properties also ensure that blend films, within a completely organic character, are formed as truly active layers. The fluorescent and phosphorescent emission properties of the phenazine molecules, depending on their conformational states, allowed relatively intense emissions in blue, green, red and also in white, without the need to mix different materials. Although the results of absorption of the blended films have shown no characteristics of the guest molecules, due to their relatively low concentrations, the excitation of them occurs directly by the incident laser beam. The steady-state spectroscopy for the monomer and dimer singlet fluorescence states of respective blue and green emissions of the films were investigated. The analysis of their temporal decays were done using a different approach based on the Exponentially Modified Gaussian (EMG) function. The phosphorescent emissions of the triplet steady-states, occurring in the orange or in the red wavelength regions, were observed to be correlated, respectively, to the formation of guest monomers or to the guest dimers singlet states.

Quantum error correction and large $N$

In recent years quantum error correction (QEC) has become an important part of AdS/CFT. Unfortunately, there are no field-theoretic arguments about why QEC holds in known holographic systems. The purpose of this paper is to fill this gap by studying the error correcting properties of the fermionic sector of various large NN theories. Specifically we examine SU(N)SU(N) matrix quantum mechanics and 3-rank tensor O(N)^3O(N)3 theories. Both of these theories contain large gauge groups. We argue that gauge singlet states indeed form a quantum error correcting code. Our considerations are based purely on large NN analysis and do not appeal to a particular form of Hamiltonian or holography.

Charge–Transfer Fluorescence and Room-Temperature Phosphorescence from a Bisamide-Based Derivative

The development of organic luminescent materials with bimodal emissions of both fluorescence and room-temperature phosphorescent (RTP) remains a challenge. The investigation of the relationship between fluorescence and RTP performance is especially rare. In this work, we obtained an organic luminescent molecule, 1,4-phenylenebis((9H-carbazol-9-yl)methanone) (PBCM), which exhibits bimodal emissions of cyan fluorescence and yellow RTP in its crystalline state through adopting an electron donor–acceptor–donor (D–A–D) structure. The charge–transfer (CT) effects in the bimodal luminescent properties of PBCM, as well as the single-crystal structures and thermal properties, were investigated. It was found that the CT effect in the singlet states effectively reduces the ∆Est and promotes the ISC processes, resulting in an efficient phosphorescence of PBCM at room temperature. In addition, many strong intermolecular interactions are formed between the donor and acceptor parts of adjacent molecules, leading to the rigid configurations and compact packing of molecules in crystals, which was also confirmed to facilitate the efficient bimodal emissions of PBCM.

Understanding the Electronic Interactions, Vertical Excitation Analysis, and the Photovoltaic Properties of 5-(2-ethylhexyl)-1,3-di(furan-2-yl)-4H-thieno[3,4-c]pyrrole-4,6-dione

Organic photovoltaic (OPV) are a promising new class of photovoltaic as they offer several advantageous features including large surface area to volume ratio, low cost, lightweight properties, and durability. The limitation of OPV that prevented their adoption for use in the past was their low power conversion efficiency (PCE) but that drawback has been solved by the development of the donor-acceptor-donor (D-A-D) system with high conversion efficiencies. Herein, 5-(2-ethylhexyl)-1,3-di (furan-2-yl)-4H-thieno [3,4-c]pyrrole-4,6(5H)-dione (FTPF), a donor-acceptor-donor monomer was investigated for its optoelectronic, excited state, and photovoltaic properties using a density functional theory (DFT) and time-dependent density function theory (TD-DFT) at the B3LYP/6-31+G(d,p) theoretical method. The spectral analysis (FT-IR, UV-vis, and NMR), electronic molecular properties, natural bonding orbitals (MOs and NBOs) analyses, and excitation were studied at this level in gas, hexane, DMF, and THF. The UV-Vis spectrum showed that FTPF exhibited mono-absorption in non-polar gas and hexane, but dual absorptions in polar solvents (DMF and THF) having maximum wavelength (λmax) at 351, 359, 371 and 373 nm in gas, hexane, THF, and DMF respectively, showing a major red shift as solvent became polar. The hole-electron excitation studies of the first five singlet states: S0→S1/S2/S3/S4/S5 in gas and DMF phases showed that S0→S1 is a delocalized π→π* Rydberg excitations originating from the D-A-D C=C π bonds, S0→S2 is π→π* local excitation, while S0→S3 in water occurred as an n→π* from the carbonyl and azolide groups of the acceptor unit, but n→π* charge transfer (CT) in DMF. The S0→S5 in water and S0→S4 are n→π* LE type excitations, while S0→S5 in DMF conformed to a delocalized π→π* excitation extended over the D-A-D conjugated backbone. FTPF provided efficient electron injection in all studied solvent; showing that FTPF is a sure-bet for opto-electronic application.

Chirality enhances oxygen reduction

Controlled reduction of oxygen is important for developing clean energy technologies, such as fuel cells, and is vital to the existence of aerobic organisms. The process starts with oxygen in a triplet ground state and ends with products that are all in singlet states. Hence, spin constraints in the oxygen reduction must be considered. Here we show that electron transfer from chiral electrodes to oxygen (oxygen reduction reaction) is enhanced over that from achiral electrodes. We demonstrate lower overpotentials and higher current densities for chiral catalysts versus achiral ones. This finding holds even for electrodes composed of heavy metals with large spin orbit coupling. The effect results from the spin selectivity conferred on the electron current by the chiral assemblies, the chiral induced spin selectivity effect.

An Operator Product Expansion for Form Factors II. Born level

Form factors in planar $$ \mathcal{N} $$ N = 4 Super-Yang-Mills theory admit a type of non-perturbative operator product expansion (OPE), as we have recently shown in [1]. This expansion is based on a decomposition of the dual periodic Wilson loop into elementary building blocks: the known pentagon transitions and a new object that we call form factor transition, which encodes the information about the local operator. In this paper, we compute the two-particle form factor transitions for the chiral part of the stress-tensor supermultiplet at Born level; they yield the leading contribution to the OPE. To achieve this, we explicitly construct the Gubser-Klebanov-Polyakov two-particle singlet states. The resulting transitions are then used to test the OPE against known perturbative data and to make higher-loop predictions.