scholarly journals Exchange Interaction in Complex Bis[(1,3-Dithiole-2-Thione-4,5-Dithiolato)-di-(Carbonyl)-Cyclopentadienyl Iron(II)]

2009 ◽  
Vol 2009 ◽  
pp. 1-4
Author(s):  
S. V. Vitushkina ◽  
D. V. Ziolkovskiy ◽  
V. A. Starodub ◽  
I. A. Presniakov ◽  
A. V. Sobolev ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Triplet State ◽  
Temperature Dependence ◽  
Exchange Interaction ◽  
Spin Density ◽  
Wide Temperature Range ◽  
Electronic States ◽  
Dft Method ◽  
Triplet States ◽  
Singlet And Triplet States

The splitting of the quasidegenerate electronic states in dinuclear bis[(1,3-dithiole-2-thione-4,5-dithiolato)-di-(carbonyl)-cyclopentadienyliron (II)] complex with the bridging, S–S coupled, dimerized sulfur-rich dithiolate ligands, [Fe(C5H5)(CO)2(C3S5-C3S5)Fe(C5H5)(CO)2] (I) was found by the means of Mössbauer spectroscopy and by the measurement of the temperature dependence of magnetic susceptibility in a wide temperature range from 2 K to 300 K. The experimental results were confirmed by the calculations of the singlet and triplet states of the complex, as well as of the distribution of spin density within the bounds of the DFT method in the B3LYP/6-31(dp)G basis. In the more stable triplet state, the spin density is significantly delocalized, which is a characteristic of olefindithiolate complexes.

Ab-initio Calculation on Methylnitrenium Ion (CH3NH)+

1974 ◽  
Vol 29 (5) ◽  
pp. 832 ◽  
Author(s):  
R. Gunde ◽  
A. Ažman
Keyword(s):  
Triplet State ◽  
Ab Initio ◽  
Ground State ◽  
Ab Initio Calculation ◽  
Triplet States ◽  
Singlet And Triplet States

Abstract Ab initio calculation were carried out on the singlet and triplet states of the methylnitrenium ion. The triplet state is the ground state for all values of angle at nitrogen.

scholarly journals CNDO/S-CI Calculations of some Carbonyl-containing Organic Luminophores with a Stilbene Subchromophore

1985 ◽  
Vol 40 (8) ◽  
pp. 859-863
Author(s):  
G. Olbrich ◽  
P. Nikolov ◽  
F. Fratev ◽  
O. E. Polansky
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Electronic States ◽  
Solvent Polarity ◽  
Energy Separation ◽  
Triplet States ◽  
Organic Luminophores ◽  
Calculated Energy ◽  
Singlet And Triplet States ◽  
Ci Calculations

For a series of carbonyl-containing compounds with a stilbene subchromophore the lowest ten singlet and triplet states have been calculated with the aid of the CNDO/S-CI method. The results were used to rationalize the relative ordering of the lowest-lying S(ππ*), S(ππ*), T(ππ*), and T(ππ*) electronic states. Using the calculated energy separation between the singlet ππ*and nπ* states and between the singlet ππ* and triplet nπ* states the fluorescence ability of the compounds studied is interpreted. The connection between the structure of the compounds and their fluorescence is discussed. It is shown that an increase of the solvent polarity in some cases may lead to an inversion of the singlet nπ* and ππ* levels and to an enhancement of the fluorescence quantum yield.

Magnetic properties of rare earth chromium borates at high temperatures

2021 ◽  
pp. 166-170
Author(s):  
O.K. Kuvandikov ◽  
◽  
N.I. Leonyuk ◽  
V.V. Malsev ◽  
M.M. Kuzmin ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Temperature Dependence ◽  
High Temperatures ◽  
Wide Temperature Range ◽  
Magnetic Moments ◽  
Chemical Formula ◽  
Temperature Range ◽  
Curie Temperatures

Temperature dependence of the magnetic susceptibility has been studied for rare-earth borates NdCr3(BO3)4, SmCr3(BO3)4 and LuCr3(BO3)4 by the Faradey method in the wide temperature range (300-1200 K). The dependence for each phase follows the Curi - Weis law. The Curie temperatures, Neel temperatures and magnetic moments corresponding to the chemical formula of the crystals, have been found.

Emission and Deactivation of the Excited States of 2,3-Pentanedione

1972 ◽  
Vol 50 (9) ◽  
pp. 1338-1344 ◽  
Author(s):  
A. W. Jackson ◽  
A. J. Yarwood
Keyword(s):  
Triplet State ◽  
Gas Phase ◽  
Excited States ◽  
Singlet State ◽  
Triplet States ◽  
Excited Singlet ◽  
Vibrationally Excited ◽  
Singlet Level ◽  
Singlet And Triplet States ◽  
Fluorescence And Phosphorescence

Vibrationally excited singlet and triplet states of 2,3-pentanedione are formed by photolysis at 365 nm. The processes removing these excited states in the gas phase are studied by measuring the fluorescence and phosphorescence yields. Fluorescence can occur from the vibrationally excited, as well as the vibrationally equilibrated, singlet state. The fluorescence and phosphorescence data are considered in terms of mechanisms which involve either weak or strong collisions. Although the data cannot distinguish between the alternatives, there are two significant conclusions. The fluorescence data require that emission occur from at least two levels in the singlet manifold. To explain the phosphorescence data, the highest emitting singlet level must not lead to a vibrationally equilibrated triplet state.

scholarly journals Передача электронной энергии в одиночной донор-акцепторной паре с триплет-триплетным поглощением

2019 ◽  
Vol 127 (7) ◽  
pp. 7
Author(s):  
И.С. Осадько
Keyword(s):  
Energy Transfer ◽  
Triplet State ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Triplet States ◽  
Single Donor ◽  
Singlet And Triplet States ◽  
Fret Efficiency ◽  
Weak Luminescence ◽  
Triplet Absorption

AbstractFörster resonance energy transfer (FRET) is examined in a single donor (D)–acceptor (A) pair whose molecules have both singlet and triplet states. Two cases are considered: (i) the excitation of the D–А pair occurs with the participation of a singlet band of the donor, and (ii) the excitation also involves the participation of an additional triplet–triplet absorption. The triplet state of the donor is shown to have no effect on the expression for the FRET efficiency, but it generates off intervals in the fluorescence track of both the donor and the acceptor. The triplet state of the acceptor strongly affects the expression for the FRET efficiency, making the complete energy transfer impossible and generating off intervals in the acceptor fluorescence track. It is shown that, if the light can excite not only the singlet transition in the donor, but also the triplet–triplet absorption band, then a weak luminescence appears in off intervals, which is orders of magnitude weaker than that in on intervals.

scholarly journals The band systems ending on the 1 s σ2 s σ 1 Ʃ g ( 1 X g ) state of H 2 —Part I

1937 ◽  
Vol 160 (903) ◽  
pp. 487-507 ◽  
Keyword(s):  
Ground State ◽  
Principal Quantum Number ◽  
Electronic States ◽  
Ground Level ◽  
Triplet States ◽  
Private Communication ◽  
Singlet States ◽  
Singlet And Triplet States ◽  
State 1 ◽  
Atomic Helium

It is now well established that the electronic states of the band systems of H 2 have a close analogy to those of atomic helium and consist of a set of singlet states and a set of triplet states. There are no known combinations between singlet and triplet states. The ground level of H 2 is the v = 0, K = 0 level of the even state 1 s σ 1 s σ 1 Ʃ g . The possible states with one electron excited to principal quantum number 2 are 1 s σ 2 s σ 1 Ʃ g , 1 s σ 2 p σ 1 Ʃ u , 1 s σ 2 pπ 1 II u , 1 s σ 2 s σ 3 Ʃ g , 1 s σ 2 p σ 3 Ʃ g and 1 s σ 2 pπ 3 II u Of these the only ones which can go down to the ground state are 1 s σ 2 p σ 1 Ʃ u and 1 s σ 2 pπ σ 1 Ʃ u on account of the triplet ↔ singlet and odd ↔ odd and even ↔ even prohibitions. The bands with these transitions are well known and understood both in emission and absorption. A large number of emission band systems which go down to the states 1 s σ 2 p σ 1 Ʃ u and 1 s σ2 pπ σ 1 II u from higher even states have been found and analysed so that we now have quite discovered, and most of those involving the v = 1 level, which he has greatly extended, I am indebted to a private communication from Professor Dieke. Incidentally the success of this method of locating the position of 1 s σ3 pπ 1 II u is to some extent also a confirmation of my identification of 3 1 O as 1 s σ 3 s σ 1 Ʃ g .

Fluorescence and Phosphorescence of 2,3-Pentanedione

1972 ◽  
Vol 50 (9) ◽  
pp. 1331-1337 ◽  
Author(s):  
A. W. Jackson ◽  
A. J. Yarwood
Keyword(s):  
Quantum Yield ◽  
Triplet State ◽  
Temperature Variation ◽  
Delayed Fluorescence ◽  
Triplet States ◽  
Yield Data ◽  
System A ◽  
Singlet And Triplet States ◽  
Fluorescence And Phosphorescence

The fluorescence and phosphorescence yields on photolysis of 2,3-pentanedione were investigated at various temperatures. The processes involved in the formation and removal of both the singlet and triplet states are considered. The data agree qualitatively and quantitatively with the results of an earlier study of the lifetime of the triplet state. It is shown that delayed fluorescence is not observed in the pentanedione system. A mechanism is proposed that can correlate the temperature variation of both the lifetime and quantum yield data.

Potential energy curves and dipole moment of NF molecule with inner electron correlation

2015 ◽  
Vol 93 (12) ◽  
pp. 1544-1550 ◽  
Author(s):  
Mingjie Wan ◽  
Huafeng Luo ◽  
Chengguo Jin ◽  
Duohui Huang ◽  
Fanhou Wang
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Correlation Energy ◽  
Dipole Moments ◽  
Electronic States ◽  
Spectroscopic Properties ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Triplet States ◽  
Singlet And Triplet States

The potential energy curves and dipole moments for the low-lying electronic states of the NF molecule are found by using highly accurate multireference configuration interaction plus the Davidson correction with the AV5Z basis set. All 16 electrons are used in the correlation energy calculations, which are used to characterize the spectroscopic properties of a manifold for singlet and triplet states. X3Σ–, a1Δ, b1Σ+, A3Π, 23Σ–, 23Π, 21Δ, 33Σ–, 13Σ+, and 13Δ electronic states correlate with the two lowest dissociation channels N(4Su) + F(2Pu) and N(2Du) + F(2Pu) are investigated. Note that the b1Σ+ state has two depth wells, but only one depth well was observed in the experiment. The spectroscopic parameters (Re, ωe, ωeχe, De, Be, and Te) are derived, which are in excellent agreement with the available experimental data and the other theoretical values. The molecular parameters and dipole moments for the ground and excited states are also obtained.

Photocyclization of 2-vinylbiphenyls: stereochemistry of the triplet state cyclization

1985 ◽  
Vol 63 (8) ◽  
pp. 2192-2196 ◽  
Author(s):  
René Lapouyade ◽  
Claude Manigand ◽  
Aziz Nourmamode
Keyword(s):  
Excited State ◽  
Triplet State ◽  
Trans Isomer ◽  
Singlet State ◽  
Membered Ring ◽  
Quantum Yields ◽  
Triplet States ◽  
Singlet Excited State ◽  
Singlet And Triplet States ◽  
Cis Isomer

The photochemistry of five- to eight-membered ring containing 2-cycloalkenyl biphenyls was examined under direct and sensitized irradiation. From the singlet excited state only trans 9,10-cycloalkyl-9,10-dihydrophenanthrenes were obtained. From the triplet state the trans isomer was exclusively formed from 2-cyclopentenyl and 2-cyclohexenyl biphenyls while the cis isomer also appeared with 2-cycloheptenyl and 2-cyclooctenyl biphenyls. We propose that the cis isomers resulted from the cyclization of the perpendicular triplet of cycloheptenyl biphenyl and from the perpendicular and trans triplet of cyclooctenyl biphenyl. Whereas the photocyclization of 2-vinylbiphenyls was regarded as a singlet-state reaction, the quantum yields of reaction of 2-cycloalkenyl biphenyls, from both singlet and triplet states, were high (ΦS = 0.20–0.26; ΦT = 0.15–0.46).

Formation of a Bound State in the Presence of Repulsive Interaction

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3242-3250 ◽  
Author(s):  
J. D. Fan ◽  
Y. M. Malozovsky
Keyword(s):  
Triplet State ◽  
Multiple Scattering ◽  
Singlet State ◽  
Effective Interaction ◽  
Bound State ◽  
Repulsive Interaction ◽  
Triplet States ◽  
Hartree Potential ◽  
Singlet And Triplet States ◽  
T Matrix

We have examined the effective interaction of two fermions in terms of the T-matrix and shown that there are two different series of ladder diagrams in describing the effective interaction: (1) the exchange ladder diagrams giving rise to the T-matrix for the triplet state with poles for attractive interaction and (2) the Hartree ladder diagrams describing the multiple scattering on the Hartree potential and producing the T-matrix for the singlet state with poles for repulsive interaction. It is verified that a bound state of two fermions in the singlet state exists only in the presence of repulsive interaction between them. We further argue that the potential in the Schrodinger equation should be spin-dependent to describe both the singlet and triplet states.

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