The influence of the temperature of a liquid on multibubble sonoluminescence of Tb3+ ions in an aqueous solution

Abstract

Sonoluminescence is the emission of light from cavitation bubbles during the sonolysis of liquids [1]. One of substantiations of gas glow in a liquid is the presence of metal atom lines in multibubble sonolu minescence (MBSL) spectra [2][3][4][5][6][7]. The appearance of lines is easily understood only for solutions of vola tile compounds Me(CO) x (Me = Fe, Cr, Mo, W). They easily vaporize and decompose in bubbles, which is followed by the excitation of Me in collisions with hot particles [2,3]. Conversely, the luminescence of metal atoms in aqueous solutions of nonvolatile alkali halide salts has attracted much interest [4][5][6][7]. The mechanism of their interaction with bubbles is still the focus of attention of researchers concerned with sonochemical processes [8].In addition to metal atom sonoluminescence effects mentioned above, the MBSL of Ln 3+ ions (Ln = Ce, Eu, Tb, Gd, Dy) in aqueous solutions of LnCl 3 was recently observed [9][10][11]. A hypothesis of the excitation of Ln 3+ was suggested. According to this hypothesis, nonvolatile lanthanide, like alkali halide, salts got into bubbles. This hypothesis is difficult to prove because of a possible contribution of sonophoto luminescence (SPL) to glow; that is, reemission by Ln 3+ ions in solution volume of partly absorbed radia tion of electronically excited sonolysis products emit ted from bubbles. Indeed, such reemission completely explains glow of Ce 3+ , whose luminescence was caused by d-f transitions [9,12]. However, glow in the sonolysis of ions emitting light in intrashell f-f transi tions (Eu 3+ , Tb 3+ , Gd 3+ , and Dy 3+ ) cannot be explained by SPL [9][10][11][12]. In addition, intrabubble excitation of these ions was also substantiated by the isotope effect (an increase in the intensity of lan thanide luminescence caused by solvent deuteration), which was observed for MBSL in solutions of TbCl 3 [13,14]. An anomalously low value of this effect com pared with the effect observed for photoluminescence (PL) was explained by the presence of two stages (gas and liquid phase) of deactivation of long lived (longer than 10 -4 s) excited states of Tb 3+ ions during MBSL, whereas deactivation during PL occurs in the liquid phase only. To substantiate the hypothesis of intrabub ble f-f excitation of Ln 3+ ions, we studied the influ ence of the temperature of a liquid on MBSL of Tb 3+ ions in aqueous solutions of TbCl 3 in the atmosphere of air.To take into account various factors influencing the intensity of MBSL of terbium as the temperature var ied, we comparatively studied light absorption by the Tb 3+ ion and sonoluminescence and PL of this ion and also the sonoluminescence of a solution of GdCl 3 (Fig. 1). Glow had to be recorded during the sonolysis not only of a solution of terbium but also of a solution of gadolinium for correctly taking into account back ground MBSL of the solvent at 546 nm (the region of the 5 D 4 -7 F 5 radiation transition maximum of the Tb 3+ ion). Characteristic luminescence of Ln 3+ ions is observed in MBSL spectra again...

Определение время жизни люминесценции Ce-=SUP=-3+-=/SUP=- методом время-коррелированного счета фотонов при сонолюминесценции водного раствора CeCl-=SUB=-3-=/SUB=-

“…В спектрах СЛ водных растворов солей лантанидов зарегистрированы полосы высвечивания d− f и f − f переходов их ионов [3][4][5]. Показано, что ионы могут возбуждаться неупругими соударениями внутри пузырька, попадая в пузырек с нанокаплями раствора по механизму [6], или в объеме раствора, поглощая СЛ-фотоны.…”