We studied the thermal and magnetic properties of a cylindrical quantum dot in the presence of external electric and magnetic fields. The energy spectrum and wave functions for the quantum dot of asymmetric confinement are obtained by solving the Schrödinger wave equation analytically. The energy levels are employed to calculate the canonical partition function, which in turn is used to obtain specific heat, entropy, magnetization, and susceptibility. These thermal and magnetic quantities are found to have direct dependence on confinement length, magnetic field, and temperature, thus the parameters of the system can be tuned to fit into more than one application. PACS Nos.: 78.40.Fy, 75.75.-c, 68.65.Hb. Résumé : Nous étudions ici les propriétés thermiques et magnétiques de points quantiques cylindriques en présence de champs électriques et magnétiques externes. Nous solutionnons analytiquement l'équation de Schrödinger pour le spectre en énergie et les fonctions d'ondes de ce point quantique de confinement asymétrique. Les énergies propres permettent de calculer la fonction de partition canonique qui nous donne la capacité calorifique, l'entropie, la magnétisation et la susceptibilité. Nous trouvons que ces quantités thermiques et magnétiques dépendent directement de la longueur de confinement, du champ magnétique et de la température et qu'ainsi les paramètres du système peuvent être accordés pour satisfaire plus d'une application. [Traduit par la Rédaction]

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Multiple exciton generation (MEG) is a promising process to improve the power conversion efficiency of solar cells. PbSe quantum dots (QDs) have shown reasonably high MEG quantum yield (QY), although the photon energy threshold for this process is still under debate. One of the reasons for this inconsistency is the complicated competition of MEG and hot exciton cooling, especially at higher excited states. Here, we investigate MEG QY and the origin of the photon energy threshold for MEG in PbSe QDs of three different sizes by studying the transient absorption (TA) spectra, both at the band gap (near infrared, NIR) and far from the band gap energy (visible range). The comparison of visible TA spectra and dynamics for different pump wavelengths, below, around and above the MEG threshold, provides evidence of the role of the Σ transition in slowing down the exciton cooling process that can help MEG to take over the phonon relaxation process. The universality of this behavior is confirmed by studying QDs of three different sizes. Moreover, our results suggest that MEG QY can be determined by pump-probe experiments probed above the band gap.

The physiological significance of calcium ions such as the role in cellular signalling, cell growth,e tc. have driven the development of methods to detect and monitort he level of Ca 2 + ions, both in vivo and in vitro. Although various approaches for the detection of calcium ions have been reported, methods based on small molecular fluorescent probesh ave uniquea dvantages including smallp robe size, easy monitoring of detection processes and applicability in biological systems. In this review article, we will discusst he progress in the development of Ca 2 + -binding fluorescent probesb yt aking into accountt he types of chelating groups that have been employed for Ca 2 + binding.Scheme1.Designs trategyo faf luorescentsensor.[a] Dr.Roopa

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