Determination of a High Potential Barrier Hindering Internal Rotation from the Microwave Ground State Spectrum The Methylbarrier of Antiperiplanar and Synclinal Normal Propyl Fluoride

1986 ◽  
Vol 41 (7) ◽  
pp. 944-954
Author(s):  
W. Kasten ◽  
H. Dreizler

The microwave ground state spectra of antiperiplanar and synclinal normal propyl fluoride have been measured by microwave Fourier transform spectroscopy and analysed for methyl torsion fine structure. Additionally, the spectrum of the synclinal form in the first excited state of the methyl group has been investigated due to methyl torsion. The difference of the values determined for the barrier heights in the ground and first excited state of the synclinal form is discussed by an approximate treatment of the coupling of CH3 and C - C torsional motions. As high J transitions were measured a centrifugal distortion analysis was necessary.

1985 ◽  
Vol 40 (6) ◽  
pp. 575-587 ◽  
Author(s):  
J. Gripp ◽  
H. Dreizler ◽  
R. Schwarz

For ethylbromide a determination of the parameters of internal rotation is given derived from the rotational spectrum of the torsional and vibrational ground state. The Br-hyperfine structure is reanalysed with higher precision. As high J transitions were measured a centrifugal distortion analysis was necessary.


2019 ◽  
Vol 11 ◽  
Author(s):  
G. Kalliabakos ◽  
S. Kossionides ◽  
P. Misailides ◽  
C. T. Papadopoulos ◽  
R. Vlastou

A combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS) were utilized in order to obtain information on the depth distribution of sulphur and copper in artificially produced and natural patina layers. The copper profiling was performed by using the reaction 63Cu(p,p'y)6 3Cu and detecting the 1327 keV γ-ray deexciting the third excited state to the ground state of 6 3Cu produced. For the determination of sulfur the 2230 keV γ-ray was used, deexciting the first excited state to the ground state of 32S formed through the reaction 3 2S(p,p'y)3 2S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. Supporting information on the depth distribution of oxygen and the other elements of the patina samples was obtained by p-RBS (Ep = 1.5 MeV; θ = 160°).


2019 ◽  
Vol 10 ◽  
pp. 1
Author(s):  
S. Kossionides ◽  
G. Kaliambakos ◽  
R. Vlastou ◽  
C. T. Papadopoulos

The concentration and depth profile of Cu and S in patinna samples have been determined by using Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectroscopy (RBS). For the NRA the differential cross section was mesaured for the 1327 keV 7-ray deexciting the third excited state to the ground state of 6 3Cu through the reaction 63Cu(p,p'7), as well as, for the 2230 keV γ-ray deexciting the first excited state to the ground state through the resonant reaction 32S(p,p'7). The mesaurements of both excitation functions were performed in the energy range 3.0 - 3.7 MeV in 20 keV steps and at an angle of 125°.


1982 ◽  
Vol 37 (9) ◽  
pp. 1035-1037 ◽  
Author(s):  
J. A. Hardy ◽  
A. P. Cox ◽  
E. Fliege ◽  
H. Dreizler

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.


The following values of nuclear reaction energies have been obtained: 6 Li (p,α) 3 He, Q = 4.023 MeV; 8 Li (d ,p) 7 Li, Q = 5.028 MeV; 6 Li (d, p ) 7* Li, Q= 4.553 MeV; 6 Li( d,α ) α, Q = 22.396 MeV; 7 Li (p , α ) α , Q = 17.352 MeV; 9 Be (p, α ) 6 Li, Q = 2.126 MeV; 9 Be (p, d ) 8 Be, Q = 0.560 MeV; 9 B e (d, α ) 7 Li, Q = 7.153 MeV; 9 Be (d, α ) 7* Li, Q = 6.675 MeV; n B (p , α ) 8 Be, Q = 8.589 MeV; 15 N (p, α ) 12 C, Q = 4.962 MeV. The average value of th e first excited level in 7 Li has been found to be 0.477 ± 0.003 MeV from the difference between the ground state and first excited state groups of the 6 Li (d, p) 7 Li and 9 Be (d, α) 7 Li experiments. A comparison is made between the above results and recent figures quoted by other workers in this field, and it is found that no systematic discrepancies are conspicuous, except that our energies are on the average higher than those found at M.I.T. and C.I.T., probably due to the differences between the momentum and energy standards used by these groups of workers and those measured by us.


2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG≠ values that vary in the range 92.8–127 kJ mol−1 at 310 K. A value of ∼10–30 kJ mol−1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O2 from the ground to the first excited state (1Δg, singlet oxygen) is equal to 92 kJ mol−1. So, the ΔG≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (1Δg first excited) state. The similarity of the ΔG≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (1Δg), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, 1Δg, state (92 kJ mol−1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10–30 kJ mol−1 for their diffusion). The ΔG≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.


1983 ◽  
Vol 38 (4) ◽  
pp. 447-451 ◽  
Author(s):  
J. Demaison ◽  
D. Boucher ◽  
J. Burie ◽  
A. Dubrulle

The rotational spectrum of ethyl acetylene has been investigated between 70 and 320 GHz. A Coriolis interaction has been found between the first excited state of the methyl torsion and the C - C = C in plane deformation. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group amounts to 3271 cal/mole.


1983 ◽  
Vol 38 (9) ◽  
pp. 1010-1014 ◽  
Author(s):  
W. Stahl ◽  
H. Dreizler ◽  
M. Hayashi

Abstract We present an analysis of the rotational spectrum of ethylchloride-35Cl in the ground state. The 35Cl-hfs analysis was extended and the barrier to internal rotation determined from narrow splittings of high J-transitions.


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