Untersuchungen des spektralen Ausbleichens von S?ttigungsabsorbern

Ohne ZusammenfassungSiehe ausführliche Publikation Z. angew. Math. Phys.22, 458 (1971).     

Resonance Raman spectrum of the transient (SCN)−2 free radical anion

The resonance Raman spectrum of the transient species (λ_max = 475 nm, τ_{$\text{1}\text{2}$} = 1.6 μs) formed by pulse radiolysis of aqueous solutions of thiocyanate, SCN^2?, is reported. The spectrum is discussed in terms of the previous assignment of this transient to the radical anion, (SCN)^?₂. The observed vibrational frequencies of the radical anion are consistent with substantial weakening of the SS and the CN bonds are compared with neutral thiocyanogen.     

SENSITIZED TRIPLET FORMATION OF CHLOROPHYLL-A AND ß-CAROTENE

The naphthalene-sensitized formation of triplet excited chlorophyll-a (Chl-a) and all-transß-carotene has been studied by pulse radiolysis. The rate constants for transfer of triplet energy from naphthalene to Chl-a and all-transß-carotene in benzene at 25°C are (3.6 ± 0.6)·10⁹M^-1 s^-1 and (10.7 ± 1.2)·10⁹M^-1 s^-1, respectively. The decays of the excited triplet states of naphthalene, Chl-a and all-transß-carotene all follow a mixed first-and second-order mechanism. The first-order rate constant for triplet decay is strongly dose dependent for naphthalene but only slightly dependent and independent of dose for Chl-a and all-transß-carotene, respectively. The rate constants for triplet-triplet annihilation are (1.4 ± 0.3)·10⁹M^-1 s^-1 for Chl-a and (3.6 ± 0.4)·10⁹M^-1 s^-1 for all-transß carotene. The nearly constant ratio k(ß-carotene)/k(Chl-a) for the bimolecular triplet energy transfer rate constants is discussed in terms of the molecular shapes of the two molecules. The energetics of the triplet-triplet annihilation of all-transß-carotene are discussed, and it is proposed that production of the excited ¹A_B state may be a major route in the annihilation process.     

Spectral measurement of the Hall angle response in normal state cuprate superconductors

We measure the temperature and frequency dependence of the complex Hall angle for normal state YBa(2)Cu(3)O(7) films from dc to far-infrared frequencies (20-250 cm(-1)) using a new modulated polarization technique. We determine that the functional dependence of the Hall angle on scattering does not fit the expected Lorentzian response. We find spectral evidence supporting models of the Hall effect where the scattering Gamma(H) is linear in T, suggesting that a single relaxation rate, linear in temperature, governs transport in the cuprates.     

HVEM Study of the Development of the Recrystallization Texture in Deformed Copper Single Crystals

〈110〉-orientated single crystals of high purity copper were deformed in tension up to 80% elongation. Sections of the deformed material were examined by HVEM before and after annealing in situ. Additional measurements by a texture goniometer confirmed and supplemented the metallographic results. The orientations of all recrystallized micrograins can be interpretated as the result of multiple annealing twinning. Since the grain boundary energy may be lowered by twinning the new orientations may be selected for this reason. These results can explain the recrystallization textures observed by X-ray techniques.