scholarly journals Electronic States of p-Benzoquinone. III. Calculation of the Out-of-plane Vibrational Frequencies in the Ground Electronic State

1958 ◽  
Vol 31 (6) ◽  
pp. 728-733 ◽  
Author(s):  
Tosinobu Anno ◽  
Akira Sadô
Keyword(s):  
Electronic State ◽  
Electronic States ◽  
Vibrational Frequencies ◽  
Ground Electronic State ◽  
Out Of Plane

scholarly journals Precision measurement of the fundamental vibrational frequencies of tritium-bearing hydrogen molecules: T2, DT, HT

2020 ◽  
Vol 22 (16) ◽  
pp. 8973-8987 ◽  
Author(s):  
K.-F. Lai ◽  
V. Hermann ◽  
T. M. Trivikram ◽  
M. Diouf ◽  
M. Schlösser ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Resolution ◽  
Electronic State ◽  
Precision Measurement ◽  
Molecular Hydrogen ◽  
Vibrational Frequencies ◽  
Ground Electronic State ◽  
Hydrogen Molecules ◽  
Coherent Raman

High-resolution coherent Raman spectroscopy of all three tritium-containing molecular hydrogen – T2, DT and HT – were performed to determine the ground electronic state fundamental Q-branch transition frequencies at accuracies of 0.0005 cm−1.

The a″ vibrations of singlet propynal

1993 ◽  
Vol 71 (10) ◽  
pp. 1556-1561 ◽  
Author(s):  
J.K.G. Watson
Keyword(s):  
Electronic State ◽  
Band System ◽  
Excited Electronic State ◽  
Vibrational Frequencies ◽  
Ground Electronic State ◽  
Harmonic Potential

The a″ vibrational frequencies of all possible H and D isotopomers of propynal (HCCCHO) are shown to allow two solutions for the a″ harmonic potential constants. Equations relating the solutions are given. In the [Formula: see text] ground electronic state one solution can be rejected as chemically unrealistic, but in the [Formula: see text] excited electronic state the choice is more difficult. It is shown that a choice can be made on the basis of the observed cross-sequence intensities in the [Formula: see text] band system.

The gauche Effect. A Theoretical Study of the Topomerization (Degenerate Racemization) and Tautomerization of Methoxide Ion Tautomer

1973 ◽  
Vol 51 (15) ◽  
pp. 2423-2432 ◽  
Author(s):  
Saul Wolfe ◽  
Luis M. Tel ◽  
I. G. Csizmadia
Keyword(s):  
Electronic State ◽  
Ground Electronic State ◽  
Conformational Transformation ◽  
Molecular Orbital Calculations ◽  
Rotational Angle ◽  
Electron Pairs ◽  
Hydroxyl Proton ◽  
Gauche Effect ◽  
Internuclear Distances ◽  
Relationship Of

Non-empirical double zeta quality molecular orbital calculations on −CH2OH as a function of the C—O bond length (r), the rotational angle about the C—O bond (θ), and the pyramidal angle at carbon [Formula: see text] are described. From the stretching potential curve, E(r), it is shown that dissociation of −CH2OH proceeds to give CH2 and OH−. The rotation–inversion surface, [Formula: see text], has two types of minima; in both cases the most favorable pyramidal angle at carbon is 105°. The lower minimum corresponds to a structure (the Y conformation) having the hydroxyl proton on the external bisector of the HCH angle. The higher minimum is 6.67 kcal/mol less stable and corresponds to a structure (the W conformation) having the hydroxyl proton on the internal bisector of the HCH angle. The relationship of these results to the gauche effect is discussed and it is noted that at certain internuclear distances the nuclear–nuclear repulsion term (Enucl) may overcome the tendency of adjacent electron pairs and polar bonds to exist preferentially in that conformation which has the maximum number of gauche interactions between these electron pairs or polar bonds.The topomerization of −CH2OH, i.e., the conformational transformation from one Y conformation into another, proceeds, via the W conformation as an intermediate, by two separate events, viz. rotation about the C—O bond, having a barrier of 10.58 kcal/mol, and pyramidal inversion at carbon, with a barrier of 20.52 kcal/mol. Some factors governing the relative importance of rotation and inversion in degenerate racemization are discussed.In its ground electronic state CH3O− is 22.18 kcal/mol more stable than −CH2OH. However, in the low-lying excited states all conformations of −CH2OH are stabilized relative to CH3O−. The most stable excited state structure of −CH2OH corresponds to the energy maximum for rotation–inversion of the ground electronic state.

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