Photon upconversion materials are attractive for a wide range of applications from medicine, biology to photonics. Among them, ZnO is of particular interest owing to its outstanding combination of materials and physical properties. Though energy upconversion has been demonstrated in ZnO, the exact physical mechanism is still unknown that prevents a control of the processes. Here, we show that d...

Efficient violet-blue-emitting molecules are especially useful for applications in full-color displays, solid-state lighting, as well as in two-photon absorption (TPA) excited frequency-upconverted violet-blue lasing. However, the reported violet-blue-emitting molecules generally possess small TPA cross sections. In this work, new 1,8-diazapyrenes derivatives 3 with blue two-photon-excited fluo...

We discuss how two-photon absorption (TPA) of squeezed and coherent states light can be detected in measurements the transmitted fields. Such typically suffer from competing loss mechanisms such as experimental imperfections (i.e., imperfect photodetectors) other linear scattering losses inside sample itself, which lead to incorrect assessments two-photon-absorption cross section. evaluate sens...

The negatively charged nitrogen-vacancy defect center, (NV)(-), in diamond has been investigated theoretically for its one- and two-photon absorption properties involving the first excited state with the (3)A(2)-->(3)E transition. Time-dependent density functional theory (TD-DFT), configuration interaction with single excitation (CIS), and complete active space self-consistent field (CASSCF) we...

The development of one- and two-photon induced polymerization using CdS semiconductor quantum dots (QDs) and amine co-initiators to promote radical generation and subsequent polymerization is presented. Two-photon absorption (TPA) cross-section measurements, linear absorption, and transmission electron microscopy are used to characterize the QDs. The effectiveness of the co-initiators in increa...

ba ckground: although it is widely accepted that the pre-school age is a critical period  in  the  development of  obesity,  there  are  few  published data  on  factors contributing to variation of total energy expenditure in this age group.to investigate the contribution of body composition, gender and activity on total energy expenditure (tee) in pre-school children. m ethods: the total ener...

Technologies for the measurement of bone mineral density and other parameters of bone strength at peripheral skeletal sites have been studied since the 1960s. Single-energy Photon Absorptiometry (SPA), Radiographic Absorptiometry (RA), Radiogrametry (RG), Single-energy X-ray Absorptiometry (SXA), Peripheral Dual-energy X-ray Absorptiometry (pDXA), and Quantitative Ultrasonometry (QUS) have been...

We report calculations of one and two photon absorption (OPA and TPA, respectively) spectra of the green fluorescent protein (GFP) chromophore using the doubleharmonic parallel-mode approximation and including explicit dependence of the electronic transition moments on nuclear geometry. The non-Condon effects are found to be more significant for TPA resulting in a different shape of the spectra...

We study spectral gratings obtained as a result of two-photon excitation of the lowest electronic transition of several tetrapyrrole molecules with phase-locked pairs of femtosecond pulses. A particular dependence of these gratings on temperature indicates that mirror symmetry is present between two-photon absorption (TPA) and one-photon fluorescence spectra for non-centrosymmetrical chlorin, b...

Semi-empirical computer modelling is used to investigate spectral matching in tandem and triple-junction thin film silicon solar cells. In amorphous/microcrystalline silicon (a-Si:H/μc-Si:H) tandem cells, current mis-match is offset by an increase in fill-factor, resulting in a broad peak in efficiency versus average photon energy. For a-Si:H/a-Si:H tandem cells, photo-generated currents in bot...