Luminescence of Trivalent Lanthanide Ions Excited by Single-Bubble and Multibubble Cavitations

Abstract

This article focuses on the possibility of exciting some lanthanides (Ce(3+), Tb(3+), Gd(3+), and Eu(3+)) by ultrasound in aqueous solutions. Depending on the lanthanide ions and on the acoustic cavitation conditions (single-bubble or multibubble systems), the excitation mechanism is shown to be photoexcitation (e.g., for Ce(3+)) or collision-induced excitation (e.g., for Tb(3+)). The sonoluminescence of Tb(3+) is studied in detail at various ultrasonic frequencies, allowing quantification of the amount of quenching. The latter is much stronger in sonoluminescence than in photoluminescence due to the particular properties of acoustic cavitation. Complexation with citrate ions enhances manifold sonoluminescence of lanthanides due to reduction of intra- and inner-molecular quenching.

Plasma Formation during Acoustic Cavitation: Toward a New Paradigm for Sonochemistry

“…The photons and the "hot" particles produced inside the bubble enable exciting the nonvolatile species in solutions, thus increasing their chemical reactivity. For example, power ultrasound enables the excitation of lanthanide ions [51,52] and uranyl UO 2 2+ ions [53] in aqueous acidic solutions. The mechanism of excitation involves two stages: sonophotoluminescence (excitation with photons emitted by collapsing bubble) dominates in diluted solutions, and collisional excitation with "hot" particles would add its contribution at higher metal ions concentration.…”

Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

“…These catalytic reactions allow control of actinide oxidation states in nitric acid medium without addition of any side chemicals. On the other hand, the products of solvent sonolysis lead to quenching of the sonoluminescence of uranyl 6 and lanthanide 27 ions. Complexation with strong ligands, like phosphate or citrate ions, enhances manifold sonoluminescence of these cations due to reduction of intra-and inner-molecular quenching.…”

Атомарная люминесценция Ag при однопузырьковом сонолизе водной суспензии наночастиц серебра

“…Сообщалось об обусловленной таким попаданием люминесценции атомов, ионов и молекул при сонолизе растворов малолетучих соединений. Среди них соли щелочных и щелочно-земельных металлов (Na, Mg, K, Li, Ca, Mn, Ba) [2][3][4][5][6], ионов лантанидов Ln 3+ (Ln = Gd, Tb, Dy) [7,8], уранила (UO 2+…”

“…Данные случаи сонолюминесценции обусловлены образованием неравновесной плазмы в газопаровых кавитационных пузырьках при акустических колебаниях [12]. В плазме имеет место столкновительное электронное возбуждение с последующей люминесценцией попавших в нее ионных [7][8][9] либо молекулярных органических люминофоров [11], а также атомов металлов, возникающих вследствие термического разложения соединений этих металлов [2][3][4][5][6]10].…”