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The subject of this study is the vertical mass-spring-like oscillation of a pendant droplet and its resonant detachment, which was experimentally observed in the process of laser droplet generation from a metal wire. The process was characterized by various time series, which were generated from a sequence of infrared intensity images of the process. Following a visual inspection of pendant droplet images and an analysis of a wavelet based time-frequency map of the droplet's vertical displacement time series, the pendant droplet's oscillation is described by a time-variable mass-spring system. Based on the characteristics of the timefrequency map, the resonant nature of the pendant droplet detachment was demonstrated. Additionally, an algebraic expression was formulated, which can be used to predict the detached droplet's diameter as a function of the laser pulse frequency.

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A study of magnetism in the novel 2D spin system Ni 5 (TeO 3 ) 4 Br 2 , featuring a frustrated triangular geometry, is presented. We combine magnetization, heat capacity and high-field electron spin resonance measurements to investigate a long-range magnetic ordering below T N = 29 K. Additional peculiar behaviour, most likely related to the spin system, is observed below T = 14 K.

We present an experimental and theoretical study of the magnetically frustrated spin system in pure and substitutionally disordered compounds from the Cu 2 Te 2 O 5 X 2 family of quantum magnets. Experimental magnetic susceptibilities and specific heats were analyzed simultaneously using models of ͑i͒ isolated tetrahedra of four antiferromagnetically coupled Cu 2+ spins and ͑ii͒ coupled tetrahedra within one-dimensional chains, in both cases involving mean-field coupling to other chains. The results show that Cu 2 Te 2 O 5 X 2 compounds are true three-dimensional systems of coupled spins. Susceptibility results are consistent with the existence of a singlet-triplet gap, whereas specific heat analysis shows that the singlet-triplet gap is filled with dense singletlike excitations that contribute to finite specific heat at temperatures far below the singlet-triplet gap, but do not contribute to a magnetic response of the system. Furthermore, measured specific heat data show excessive entropy when compared to the numerical results based on a pure spin system, which we attribute to the presence of phonons. Though Cu 2+ spins are arranged in a geometrically frustrated tetrahedral antiferromagnetic configuration and spin correlation length extends beyond the single tetrahedral cluster dimension, Cu 2 Te 2 O 5 X 2 compounds do not exhibit ergodicity breaking at low temperatures, in contrast to the related geometrically frustrated kagomé and pyrochlore antiferromagnets.

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