Photodissociation dynamics of the ethoxy radical investigated by photofragment coincidence imaging

The photodissociation dynamics of the ethoxy radical (CH3CH2O) have been studied at energies from 5.17 to 5.96 eV using photofragment coincidence imaging. The upper state of the electronic transition excited at these energies is assigned to the C2A'state on the basis of electronic structure calculations. Fragment mass distributions show two photodissociation channels, OH + C2H4 and CH3 + CH2O. The presence of an additional photodissociation channel, identified as D + C2D4O, is revealed in time-of-flight distributions from the photodissociation of CD3CD2O. The product branching ratios and fragment translational energy distributions for all of the observed mass channels are nonstatistical. Moreover, the significant yield of OH + C2H4 product suggests that the mechanism for this channel involves isomerization on the excited-state surface. Photodissociation at a much lower yield is seen following excitation at 3.91 eV, corresponding to a vibronic band of the B2A' <-- X2A' transition.     

Optical investigation of ErFeO3

The absorption spectrum of single crystals of ErFeO₃ has been investigated in the red and near infrared spectral region in the temperature range between 1.2 °K and 4.2 °K and at 20 °K and 77 °K. Between 77 °K and 4.2 °K a constant splitting of the absorption lines is observed. Below the Néel-temperature of the erbium sublattice at 4.5 °K the splitting of the absorption lines increases; the saturation value extrapolated to 0 °K of the splitting of the lowest crystal field level of the⁴ I _15/2 groundterm is (6.08±0.30) cm^?1. By measuring the Zeeman effect the groundstate magnetic moment is determined asμ=(6.6±0.2)μ _B. The measured temperature dependence of the splitting of the lowest crystalfield level of the⁴I_15/2 groundterm is compared with that calculated by a Monte Carlo method.     

Optical investigation of DyFeO3

Optical absorption spectra of DyFeO₃ have been investigated at 1.2≦T≦4.2 °K, andT=77 °K From the temperature dependent lineshift a Néel temperature ofT _N=(3.8±0.5) °K is deduced for the dysprosium sublattices. The groundstate splitting due to the iron-dysprosium interactions is about 1.5 cm^?1 and due to the dysprosiumdysprosium interactions (5.0±1.4) cm^?1. Zeeman studies give the magnetic moment of the dysprosium ions asμ=(9.2±1.0)μ _B.     

Extra lines in optical spectra of Tb(OH)3

The fluorescence spectrum of Tb(OH)₃ at liquid helium temperatures exhibits a complex structure. Beside the well known electronic transitions many intense extra lines were found. The behavior of the extra lines under an external magnetic field and at various temperatures has been investigated and compared to that of the parent electronic lines. It is shown that the extra lines can be explained by internal mechanical stress.