| 1. |
- Dahlgren, T., et al.
(författare)
-
Electronic spectra of dithieno analogues of phenanthrene
- 1979
-
Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 40:3, s. 397-404
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic circular dichroism (MCD) spectra of some dithieno analogues of phenanthrene: benzo [2,1-b;3,4-b′] dithiophene (I) benzo [1,2-b;4,3-b′] dithiophene (II), benzo [1,2-c;3,4-c′] dithiophene (III) and benzo [1,2-b;3,4-b′] dithiophene (IV) are reported. For I–III the spectra corresponding to two different transition moment directions could be obtained from low-temperature linear dichroism spectra. The results compare well with theoretical energies, oscillator strengths, moment directions and MCD B-terms which were obtained from semi-empirical quantum mechanical calculations in the π-electron approximation.
|
|
| 2. |
- Nordén, Bengt, 1945, et al.
(författare)
-
The magnetic circular dichroism of five-membered ring heterocycles
- 1978
-
Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 33:3, s. 355-366
-
Tidskriftsartikel (refereegranskat)abstract
- The MCD spectra of pyrrole, furan, thiophene, selenophene and teburophene and some of their derivatives are reported and the corresponding energies, oscillator strengths, transition moment directions, and MCD terms are calculated from semi-empirical quantum mechanical calculations hi the π-electron approximation. The MCD spectrum of thiophene is only slightly perturbed by substituents, and this is also expected to be true of the quite similar MCD spectra of selenophene and tellurophene. These molecules can then be classified as “hard” chromophores. On the other hand, pyrrole and furan have different and much weaker MCD spectra which change shape considerably when substituents are introduced. The implications of these observations are further discussed.
|
|
| 3. |
- Ungstrup, E., et al.
(författare)
-
Rocket-borne particle, field, and plasma observations in the cleft region
- 1975
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 2:7, s. 345-348
-
Tidskriftsartikel (refereegranskat)abstract
- First results of comprehensive observations of magnetic and electric fields, and ambient and suprathermal plasmas above the dayside auroral oval with rocket-borne instrumentation which penetrated the cleft region are reported. Measurements were also obtained equatorward and poleward of the cleft. Convection velocities as inferred from electric field measurements were generally toward noon equatorward of the cleft and were antisunward over the polar cap. Our observations of electron temperatures, electric fields and low-frequency electrostatic noise provide strong evidence of a plasma instability (Farley-Buneman) in the E-layer, which is associated with the appearance of the ‘slant E condition’ identified in ground-acquired ionograms. The positions of these measurements relative to that of the cleft were firmly established via the determination of the plasma environment with an electrostatic analyzer.
|
|
