Ground state tunnel splitting of the methyl group in a three-fold potential

1989 ◽  
Vol 22 (11) ◽  
pp. 1941-1944 ◽  
Author(s):  
J Peternelj ◽  
I Jencic
Keyword(s):  
Ground State ◽  
Methyl Group ◽  
Tunnel Splitting

Radiation and Radiationless Processes in 2,3-Pentanedione; Phosphorescence Lifetime in the Gas Phase

1971 ◽  
Vol 49 (7) ◽  
pp. 987-993 ◽  
Author(s):  
A. W. Jackson ◽  
A. J. Yarwood
Keyword(s):  
Hydrogen Atom ◽  
Triplet State ◽  
Gas Phase ◽  
Ground State ◽  
Hydrogen Atom Abstraction ◽  
Intersystem Crossing ◽  
Phosphorescence Lifetime ◽  
Gaseous State ◽  
Methyl Group ◽  
Intramolecular Hydrogen

Fluorescence and phosphorescence are observed when 2,3-pentanedione in the gaseous state is excited at 365, 405, and 436°nm. The phosphorescence lifetime has been investigated as a function of temperature (298 to 363 °K) and concentration of the diketone (0.5 to 90 × 10−4 M). A mechanism that explains the experimental data is proposed. Apart from the radiative process and an intersystem crossing to the ground state, the triplet state 2,3-pentanedione molecules are removed by two other processes. One is a unimolecular reaction with a rate constant of 1 × 1011 exp (−11.0/RT) s−1 (consistent with an intramolecular hydrogen atom abstraction), and the other is an interaction with ground state molecules. The photochemistry of the triplet state of 2,3-pentanedione is compared with that of biacetyl to consider the effect of substitution of a hydrogen atom by the methyl group on the radiationless processes in diketones.

Gauche Propanal: Microwave Spectrum and Methyl Barrier

1987 ◽  
Vol 42 (9) ◽  
pp. 957-962 ◽  
Author(s):  
Jeremy Randeil ◽  
A. Peter Cox ◽  
H. Dreizier
Keyword(s):  
Internal Rotation ◽  
Ground State ◽  
Rotational Constant ◽  
Microwave Spectrum ◽  
Methyl Group

The barrier hindering internal rotation of the methyl group was determined by analysing ground-state A, E splittings of rotational lines in the 0+ and 0- torsional states of gauche propanal. The value V3 = 886 (10)cm-1 obtained can be compared with that obtained earlier for the cis rotamer.The A rotational constant has also been determined, its value averaged over the two lowest states being 26248.41 (5) MHz.

A Search for Isotope Effects in Chemiluminescent Reactions of Metastable Ca*( 3Pj, 1D2 ) Atoms with CH3I and CD3I Molecules

1999 ◽  
Vol 54 (3-4) ◽  
pp. 191-194 ◽  
Author(s):  
B. Pranszke ◽  
P. Kierzkowski ◽  
A. Kowalski
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Isotope Effects ◽  
Reaction Cross ◽  
Isotopic Substitution ◽  
Methyl Group ◽  
Total Collision ◽  
Reaction Cross Sections

Chemiluminescent reactions of calcium atoms in the metastable 3Pj and 1D2 states with CH3I and CD3I were studied in a beam-gas arrangement. Calcium monoiodide spectra associated with transitions from the electronic A 2Π, B 2Σ+ and C 2Π states to the X 2Σ+ ground state were recorded. Total collision and chemiluminescence cross sections were measured. It was found that isotopic substitution in the methyl group does not change the reaction cross sections and the chemiluminescence spectra.

Site-dependent effects of methylation on the electronic spectra of jet-cooled methylated xanthine compounds

2017 ◽  
Vol 19 (33) ◽  
pp. 22375-22384 ◽  
Author(s):  
Doory Kim ◽  
Key Young Yang ◽  
Hyung Min Kim ◽  
Tae-Rae Kim ◽  
Nam Joon Kim ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Electronic Spectra ◽  
Methyl Group ◽  
Torsional Barrier

The torsional barrier of methylated xanthine compounds is affected by a methyl-adjacent carbonyl or methyl group in the ground state, whereas it is governed in the excited state by the hyperconjugation interaction in the LUMO.

Determination of a High Potential Barrier Hindering Internal Rotation from the Ground State Spectrum The Methylbarrier of cis-Propanal

1982 ◽  
Vol 37 (9) ◽  
pp. 1035-1037 ◽  
Author(s):  
J. A. Hardy ◽  
A. P. Cox ◽  
E. Fliege ◽  
H. Dreizler
Keyword(s):  
Internal Rotation ◽  
Potential Barrier ◽  
Ground State ◽  
Model Errors ◽  
Centrifugal Distortion ◽  
Methyl Group ◽  
Distortion Analysis ◽  
High Potential Barrier ◽  
Double Resonances

Abstract The barrier hindering internal rotation of the methyl group was determined by analysing the splittings of rotational lines in the ground state. So model errors are minimized. The assignment was checked by double resonances and a centrifugal distortion analysis.

Microwave Spectrum and Barrier to Internal Rotation of 5-Methylisoxazole

1975 ◽  
Vol 30 (10) ◽  
pp. 1279-1281 ◽  
Author(s):  
P. J. Mjöberg ◽  
W. M. Ralowski ◽  
S. O. Ljunggren
Keyword(s):  
Internal Rotation ◽  
Ground State ◽  
Microwave Spectrum ◽  
State Transitions ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Methyl Group

Abstract The ground state rotational spectrum of 5-methylisoxazole has been studied in the region 18 000 -36 000 MHz. The A and E state transitions have been assigned.The rotational constants are A = 9230.831 MHz, B = 3559.334 MHz and C = 2610.255 MHz and the three-fold barrier to internal rotation of the methyl group was calculated to be 777.2 ± 5.5 cal mol-1 .

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