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Charge Transfer and f-f Transitions Studied by Photoacoustic Spectroscopy of [R(NO_3)_2(PicBH)_2]NO_3 and [R(NO_3)_3(PicBH)_2] Complexes (R - Rare Earth Ion)

100%

Guskos N., Papadopoulos G., Majszczyk J., Typek J., Wabia M., Likodimos V., Paschalidis D., Tossidis I., Aidinis k.

Acta Physica Polonica A

2003

vol. 103

issue 2-3

301-313

High-resolution photoacoustic spectra of trinitrato-bis[N-(2-pyridyl-methylene)-N'-benzoyl-hydrazine]R (III), (R = La, Ce, Pr), and binitrato-bis[N-(2-pyridylmethylene)-N'-benzoyl-hydrazine]R(III) nitrate (R=Y, Nd, Eu, Yb, Tb, Gd, Ho, Dy, Er) complexes, in the visual region, were studied for powder samples. Very intense photoacoustic spectra of various shapes were attributed to the intraligand transitions of the π → π* type located mainly on the C=N group and the n → π* transitions located on the carbonyl group. The intensity of these transitions essentially depends on the type of rare earth ions. The existence of f-f electron transitions could influence the relaxation processes, which play an important role in intensity determination of the above transitions. For many investigated samples the energy levels of excited states of rare earth ions were identified (f-f electron transitions). The radiation energy for some of the rare earth ions were compared with the d-d electron transitions of certain copper(II) organometallic complexes, which are very important in biogenic systems. The correlation between ions with localized and extended wave functions is suggested.

Magnetic Resonance and Dielectric Studies of a Nonlinear La_3Ga_{5.5}Ta_{0.5}O_{14} Single Crystal Doped with Erbium

100%

Bodziony T., Typek J., Orlowski M., Majszczyk J., Wabia M., Berkowski M., Ryba-Romanowski W., Guskos N., Likodimos V., Anagnostakis E.

Acta Physica Polonica A

2003

vol. 103

issue 2-3

315-322

Single crystal of erbium doped La_3Ga_{5.5}Ta_{0.5}O_{14} grown by the Czochralski method have been investigated by electron paramagnetic resonance and dielectric spectroscopy methods. Dielectric permittivity ε measurements performed in 90-440 K temperature range have shown negligible dispersion for 1 kHz - 1 MHz frequencies and a Curie-Weiss type behaviour with C=47700 K andθ=-340 K. Electron paramagnetic resonance studies have revealed the presence of two different paramagnetic, monoclinic centres. The calculated g factor values are: g_1=1.449, g_2=11. 534, g_3=4.24 for the main M_1 centre and g_1=1.98, g_2=4.169, g_3=4.25 for the weaker M_2 centre. The temperature dependence of EPR line intensity for centre M_1 and M_2 is quite different - while lines attributed to M_1 could only be observed at low temperatures, below 20 K, lines of M_2 centre persisted up to 200 K. The M_1 centre is connected with Er^{3+} ion entering substitutionally into La^{3+} site, while M_2 is probably connected with 3d ions at the same site, unintentionally introduced into the material as an admixture.

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2 Acta Physica Polonica A

2 2003

2 Guskos N.

2 Likodimos V.

2 Majszczyk J.

2 Typek J.

2 Wabia M.

1 Aidinis k.

1 Anagnostakis E.

1 Berkowski M.

1 Bodziony T.

1 Orlowski M.

1 Papadopoulos G.

1 Paschalidis D.

1 Ryba-Romanowski W.

1 Tossidis I.

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Charge Transfer and f-f Transitions Studied by Photoacoustic Spectroscopy of [R(NO_3)_2(PicBH)_2]NO_3 and [R(NO_3)_3(PicBH)_2] Complexes (R - Rare Earth Ion)

Magnetic Resonance and Dielectric Studies of a Nonlinear La_3Ga_{5.5}Ta_{0.5}O_{14} Single Crystal Doped with Erbium