An analysis of vibronic coupling in the triplet absorption spectrum of pyrazine

1993 ◽  
Vol 71 (10) ◽  
pp. 1537-1547 ◽  
Author(s):  
Gad Fischer
Keyword(s):  
Theoretical Calculations ◽  
Electronic States ◽  
Emission Spectra ◽  
Vibronic Coupling ◽  
Triplet States ◽  
Model Calculations ◽  
Singlet States ◽  
Out Of Plane ◽  
Hot Band ◽  
Triplet Absorption

New measurements of the singlet–triplet [Formula: see text] absorption spectra of pyrazine and pyrazine-d4 at longer pathlengths and higher vapour pressures have been recorded. Particular attention was paid to the hot band region to the red of the electronic origin. The activities of the out-of-plane vibrations, υ4 and υ10a, were identified in sequence bands, and their triplet state vibrational frequencies were determined, 295 (276, -d4) and 254 (194, -d4) cm−1, respectively. Model calculations were undertaken to match the observed singlet and triplet absorption and emission spectra for vibronic coupling induced by (i) υ10a(b1g), and (ii) υ4 and υ5(b2g). The calculations allowed the ordering and the relative energies of the higher lying triplet states to be determined. The 3B2u and 3B1u electronic states are above the ground electronic state by about 3.9 and 4.4 eV, respectively. The ordering is in analogy with the corresponding singlet states but opposite to that predicted by most theoretical calculations.

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 .

Vibrational potentials of the low frequency out‐of‐plane motion in the ground and excited singlet electronic states of 9,10‐dihydrophenanthrene

1992 ◽  
Vol 96 (10) ◽  
pp. 7229-7236 ◽  
Author(s):  
Marek Z. Zgierski ◽  
Francesco Zerbetto ◽  
Young‐Dong Shin ◽  
Edward C. Lim
Keyword(s):  
Low Frequency ◽  
Electronic States ◽  
Plane Motion ◽  
Excited Singlet ◽  
Out Of Plane

The photochemical reactivity of some benzoylthiophenes. IV. The effect of an adjacent methyl group on the excited state reactivity of 3-benzoylthiophene

1978 ◽  
Vol 56 (15) ◽  
pp. 1970-1984 ◽  
Author(s):  
D. R. Arnold ◽  
C. P. Hadjiantoniou
Keyword(s):  
Hydrogen Abstraction ◽  
Thiophene Ring ◽  
Emission Spectra ◽  
Photochemical Reactions ◽  
Triplet States ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
State Diagrams ◽  
Phosphorescence Emission ◽  
Intramolecular Hydrogen

The electronic absorption and phosphorescence emission spectra and the photochemical reactivity of several methyl-3-benzoylthiophenes (2- and 4-methyl-3-benzoylthiophene (1, 2), 2,5-dimethyl-3-benzoylthiophene (3), and 3-(2-methylbenzoyl)thiophene (4)) have been studied. Partial state diagrams have been constructed. The lowest energy absorption in hexane solution in every case is the carbonyl n → π* transition. The two lowest triplet states of these ketones are close in energy and, in fact, the nature of the emitting triplet (n,π* or π,π*) depends upon the position of methyl substitution and upon the solvent. The photochemical reactions studied include intramolecular hydrogen abstraction (revealed by deuterium exchange in the adjacent methyl group upon irradiation in perdeuteriomethanol solution), photocycloaddition of dimethyl acetylenedicarboxylate to the thiophene ring, and photocycloaddition of isobutylene to the carbonyl group. Generalizations, potentially useful for predicting photochemical reactivity of these and other aromatic ketones are summarized.

Triplet-triplet absorption and energy transfer from high triplet states

1971 ◽  
Vol 27 (2) ◽  
pp. 329-341 ◽  
Author(s):  
M.V. Alfimov ◽  
I.G. Batekha ◽  
Yu.B. Sheck ◽  
V.I. Gerko
Keyword(s):  
Energy Transfer ◽  
Triplet States ◽  
Triplet Absorption

scholarly journals Study of the Electric Quadrupole Moments for some Scandium Isotopes Using Shell Model Calculations with Different Interactions

2018 ◽  
Vol 15 (3) ◽  
pp. 304-309
Author(s):  
Baghdad Science Journal
Keyword(s):  
Shell Model ◽  
Theoretical Calculations ◽  
Microscopic Theory ◽  
Model Space ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Core Polarization ◽  
Model Calculations ◽  
Major Shell ◽  
Experimental Values

The electric quadrupole moments for some scandium isotopes (41, 43, 44, 45, 46, 47Sc) have been calculated using the shell model in the proton-neutron formalism. Excitations out of major shell model space were taken into account through a microscopic theory which is called core polarization effectives. The set of effective charges adopted in the theoretical calculations emerging about the core polarization effect. NushellX@MSU code was used to calculate one body density matrix (OBDM). The simple harmonic oscillator potential has been used to generate the single particle matrix elements. Our theoretical calculations for the quadrupole moments used the two types of effective interactions to obtain the best interaction compared with the experimental data. The theoretical results of the quadrupole moments for some scandium isotopes performed with FPD6 interaction and Bohr-Mottelson effective charge agree with experimental values.

Magneto-infrared spectra of matrix-isolated NiH and NiH2 molecules and theoretical calculations of the lowest electronic states of NiH2

1997 ◽  
Vol 106 (6) ◽  
pp. 2055-2059 ◽  
Author(s):  
S. Li ◽  
R. J. Van Zee ◽  
W. Weltner, Jr. ◽  
M. G. Cory ◽  
M. C. Zerner
Keyword(s):  
Infrared Spectra ◽  
Theoretical Calculations ◽  
Electronic States
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