Article
Chemistry, Physical
Bin-Bin Xie, Bo-Long Liu, Xiu-Fang Tang, Diandong Tang, Lin Shen, Wei-Hai Fang
Summary: This study generalized the quantum trajectory mean-field approach to simulate internal conversion and intersystem crossing processes, revealing new nonadiabatic relaxation pathways involving triplet states in the photoinduced ring-opening of thio-substituted heterocyclic molecules. The importance of nonadiabatic dynamics simulation in dealing with multiple electronic states with different spin multiplicities was highlighted.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Dora Voros, Sebastian Mai
Summary: In this study, the ultrafast relaxation dynamics of ortho-Nitrobenzaldehyde (oNBA) were investigated using single- and multireference electronic structure methods, potential energy surface exploration, and nonadiabatic dynamics simulations. The results showed that the initial decay from the bright ππ* state to the S-1 minimum is barrierless and involves three changes in electronic structure. The majority of the excited population decayed from S-1 through two conical intersections, leading back to the oNBA ground state or to the ketene intermediate.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Marc Alias-Rodriguez, Coen de Graaf, Miquel Huix-Rotllant
Summary: Research shows that xanthone undergoes rapid transitions in a very short period of time, with a sequential mechanism of internal conversion and intersystem crossing processes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Qi Ou, Yihan Shao, Zhigang Shuai
Summary: This study proposes a mechanism for promoting reverse intersystem crossing through light-matter coupling, which can broaden the scope of molecular design and facilitate the development of highly efficient cavity-promoted light-emitting materials.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Bin Zhang, Zhigang Shuai
Summary: Through the investigation of the reverse intersystem crossing process in cavity devices, we found that changing the detuning energy can significantly increase the rate of this process. At the same time, the incident angle and doping concentration also affect the rate. This theory provides a solid foundation for the design of highly efficient cavity-promoted light-emitting materials.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Xuezhi Bian, Yanze Wu, Hung-Hsuan Teh, Zeyu Zhou, Hsing-Ta Chen, Joseph E. Subotnik
Summary: The article explores unresolved questions in nonadiabatic dynamics with degenerate electronic states, suggesting that the inclusion of Berry force may be crucial for creating chiral induced spin separation. A robust semiclassical approach for degenerate states could potentially lead to the integration of chemical physics and spintronics.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Srijana Bhandari, Sunandan Sarkar, Alexander Schubert, Atsushi Yamada, Jameson Payne, Marcin Ptaszek, Eitan Geva, Barry D. Dunietz
Summary: The photophysical properties of tetrapyrrolic macrocycles were analyzed using a novel framework of first-principles time-dependent density functional theory, revealing an increase in intersystem crossing (ISC) rate and competing fluorescence rate with hydrogenation, leading to a lower overall ISC yield. The increase in ISC rate was found to be due to enhanced spin-orbit coupling (SOC) resulting from hydrogenation. The quantum mechanical perspective in the FGR theory and the polarization-consistent formulation achieved by the screened RSH used in the DFT calculations were crucial for predictive quality of the calculated rates.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Alexander M. Berezhkovskii, Irina V. Gopich, Attila Szabo
Summary: Kramers' procedure for calculating the rate of activated processes involves partitioning space and establishing a nonequilibrium steady state. An alternative procedure estimates the first non-zero eigenvalue of the operator that describes the dynamics. This work explores the relationship between these approaches for diffusive dynamics and shows their equivalence in special cases.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Huaiman Cao, Andrey A. Sukhanov, Marcel M. Bakirov, Yuri E. Kandrashkin, Jianzhang Zhao, Violeta K. Voronkova
Summary: Two Bodipy dimers were prepared, and it was found that the triplet excited state of the first dimer depopulates fast to the ground state, while the metastable triplet state is well-detected in the second dimer. With two iodine atoms attached, BDP-BDP-I2 exhibited a high singlet oxygen quantum yield and long intrinsic triplet state lifetime, similar to diiodoBodipy monomer. Phosphorescence experiments showed that the T1-state of BDP-BDP-I2 predominantly localizes on the diiodo Bodipy subunit and a little on the diphenyl Bodipy subunit. The presence of energy and electron transfer pathways between the two moieties of the studied dimers was implied by the observed properties.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Spectroscopy
Shu-Yu Lin, Sheng-Lung Chou, Chien-Ming Tseng, Yu-Jong Wu
Summary: We use electron bombardment to generate various silicon hydrides in an Ar matrix containing SiH4. The decomposition of SiH2 and dibridged Si2H2 in solid Ar under 365 nm irradiation is identified through infrared spectroscopy. Corresponding ultraviolet absorption spectra are recorded at each experimental stage. An intense band observed at 170-203 nm, assigned to the C 1B2 & LARR; X 1A1 transition of SiH2, is largely destroyed upon 365-nm photolysis. Moreover, a moderate band observed at 217-236 nm, assigned to the 3 1B2 & LARR; X 1A1 transition of dibridged Si2H2, is slightly reduced. These assignments are based on observed photolytic behavior, as well as the prediction of vertical excitation energies using time-dependent density functional theory and equation-of-motion coupled cluster theory.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2023)
Article
Chemistry, Physical
Angela Rodriguez-Serrano, Fabian Dinkelbach, Christel M. Marian
Summary: Multireference quantum chemical calculations were used to investigate the (reverse) intersystem crossing mechanisms of 4,5-di(9H-carbazol-9-yl)-phthalonitrile. The results indicate that the enhanced charge transfer character and low spin-orbit coupling interaction between excited states play important roles in the (R)ISC probability. Additionally, vibronic spin-orbit coupling has a small but non-negligible impact on the intersystem crossing process.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Pedro Recio, Silvia Alessandrini, Gianmarco Vanuzzo, Giacomo Pannacci, Alberto Baggioli, Demian Marchione, Adriana Caracciolo, Vanessa J. Murray, Piergiorgio Casavecchia, Nadia Balucani, Carlo Cavallotti, Cristina Puzzarini, Vincenzo Barone
Summary: This study reveals that intersystem crossing between the pre-reactive complex and the reaction barrier can control the rate of bimolecular reactions for weakly coupled potential energy surfaces, even in the absence of heavy atoms. By conducting crossed-beam experiments and computational simulations, it is found that for the O(P-3) plus pyridine reaction, the main products are pyrrole and CO, obtained through a spin-forbidden ring-contraction mechanism. The reaction rates at low to moderate temperatures are mainly dominated by intersystem crossing.
Article
Chemistry, Multidisciplinary
Braden M. Weight, Andrew E. Sifain, Brendan J. Gifford, Han Htoon, Sergei Tretiak
Summary: This study investigates the nonradiative relaxation process in single-walled carbon nanotubes (SWCNTs) with covalent surface defects through computational modeling. The results show that the chirality and defect composition of SWCNTs have a significant impact on the population relaxation, and provide insights into the relaxation process between band-edge states and localized excitonic states.
Article
Chemistry, Multidisciplinary
Braden M. Weight, Andrew E. Sifain, Brendan J. Gifford, Han Htoon, Sergei Tretiak
Summary: Recently, there has been exploration of SWCNTs with covalent surface defects for their potential use in single-photon telecommunication emission and spintronic applications. In this study, computational modeling of nonradiative relaxation in different SWCNT chiralities with single-defect functionalizations is presented. The simulations provide insights into the relaxation process between the band-edge states and the localized excitonic state, which compete with dynamic trapping/detrapping processes observed in experiments.
Article
Chemistry, Physical
Robert Smit, Zoran Ristanovic, Boleslaw Kozankiewicz, Michel Orrit
Summary: In this study, a strong excitation-induced reverse intersystem crossing (rISC) phenomenon was discovered for single perylene molecules in a dibenzothiophene matrix, leading to faster recovery from the triplet state and significantly enhanced fluorescence brightness. The intrinsic lifetimes of the two effective triplet states were found to become shorter and fluorescence brightness ultimately increased at least fourfold as excitation power increased. These results are important for understanding triplet state manipulation of single-molecule quantum emitters and improving their brightness.
Article
Biochemistry & Molecular Biology
Joel A. Rankin, Robert C. Mauban, Matthias Fellner, Benoit Desguin, John McCracken, Jian Hu, Sergey A. Varganov, Robert P. Hausinger
Article
Chemistry, Physical
Dmitry A. Fedorov, Aleksandr O. Lykhin, Sergey A. Varganov
JOURNAL OF PHYSICAL CHEMISTRY A
(2018)
Article
Chemistry, Physical
Aleksandr O. Lykhin, Seyedsaeid Ahmadvand, Sergey A. Varganov
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2019)
Article
Chemistry, Physical
Danil S. Kaliakin, Dmitri G. Fedorov, Yuri Alexeev, Sergey A. Varganov
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2019)
Article
Chemistry, Physical
Aman Ullah, Jesus Cerda, Jose J. Baldovi, Sergey A. Varganov, Juan Arago, Alejandro Gaita-Arino
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2019)
Article
Chemistry, Multidisciplinary
Andres Zavaleta, Aleksandr O. Lykhin, Jorge H. S. K. Monteiro, Shoto Uchida, Thomas W. Bell, Ana de Bettencourt-Dias, Sergey A. Varganov, Judith Gallucci
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Energy & Fuels
Ting Zhang, Chiranjivi Bhattarai, Yeongkwon Son, Vera Samburova, Andrey Khlystov, Sergey A. Varganov
Summary: Pyrolysis of anisole, a model compound for lignin in biomass tar, was studied at temperatures from 300 to 650 degrees C, revealing different decomposition products at various temperature ranges. Insights into reaction mechanisms were gained through detailed studies using density functional theory and high-level coupled cluster methods. The results will contribute to the development of predictive kinetic models for anisole decomposition and similar compounds.
Article
Chemistry, Physical
Saikat Mukherjee, Sergey A. Varganov
Summary: In excited states relaxation, internal conversion and intersystem crossing are crucial nonradiative transitions, whose interplay can lead to complex nonadiabatic dynamics. By utilizing the GAIMS method with TeraChem, nonadiabatic dynamics involving internal conversion and intersystem crossing transitions in moderate-sized molecules can be effectively modeled. The time constants describing the population transfer between different electronic states predicted by the GAIMS dynamics align well with characteristic times obtained from the analysis of the time-resolved photoelectron spectrum.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Review
Chemistry, Multidisciplinary
Vsevolod D. Dergachev, Mitra Rooein, Ilya D. Dergachev, Aleksandr O. Lykhin, Robert C. Mauban, Sergey A. Varganov
Summary: We present a nonadiabatic statistical theory (NAST) package for predicting kinetics of spin-dependent processes. The package can calculate the probabilities and rates of transitions between electronic states and account for quantum effects. It can be applied to large molecular systems and used to study slow nonadiabatic processes.
TOPICS IN CURRENT CHEMISTRY
(2022)
Article
Chemistry, Physical
Vsevolod D. Dergachev, Daria D. Nakritskaia, Sergey A. Varganov
Summary: This study investigates the accuracy of perturbation estimates of spin-orbit coupling (SOC) in lanthanide-based single-molecule magnets (SMMs) by variational solving of the Dirac equation. The results show that spin relaxation in these SMMs is influenced by the interplay between strong SOC and dynamic electron correlation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Mitra Rooein, Sergey A. Varganov
Summary: Predicting the rates of spin-dependent processes characterized by nonradiative transitions between electronic states with different spin multiplicities is crucial for understanding the mechanisms of photochemical and catalytic reactions. This study introduces three different approaches to calculate the spin-orbit coupling, transition probabilities, and rate constants between electronic states with different spin multiplicities. These approaches are implemented in the NAST software package, which predicts transition probabilities and rate constants using information from electronic structure calculations. The rates of transitions between spin states in the active site model of rubredoxin are calculated as an example.
Article
Chemistry, Multidisciplinary
Ningxin Jiang, Daria D. Nakritskaia, Jiaze Xie, Arun Ramanathan, Sergey A. Varganov, Henry S. La Pierre
Summary: The synthesis and magnetic properties of two pairs of isomeric, exchange-coupled complexes, [LnCl(6)(TiCp2)(3)] (Ln = Gd, Tb), are studied. The complexes exhibit either pseudo-octahedral or trigonal prismatic geometries, resulting in different magnetic behaviors. Ferromagnetic exchange coupling is observed in the trigonal prismatic complexes, while slow magnetic relaxation is observed in the TP-Tb complex. The electronic structures suggest that the trigonal prismatic geometry is critical for the observed magnetic behavior.
Article
Chemistry, Physical
Amir Mirzanejad, Sergey A. Varganov
Summary: Efficient activation and functionalization of the C-H bond under mild conditions are of great interest in chemical synthesis. This study investigates a previously proposed method and proposes a more favorable reaction pathway for C-H bond activation.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Andrew J. Pohlman, Danil S. Kaliakin, Sergey A. Varganov, Sean M. Casey
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2020)
Article
Chemistry, Physical
Aleksandr O. Lykhin, Sergey A. Varganov
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2020)
