Ultraviolet f→f emission and crystal field analysis for Er3+ in Cs2NaErCl6

Luminescence is reported from the 2I11/2 level of Er3+, in the cubic elpasolite lattices Cs2NaErCl6 and Cs2NaYCl6. Altogether, with the use of ultraviolet laser excitation, 11 transitions from 2I11/2 Γ7 (at 40 668 cm-1) to lower term multiplets have been observed and assigned. Transitions are also reported from the 2K13/2 Γ6 level at 32 613 cm-1. The absence of emission from 2P3/2 (at 31 367 cm-1) under the experimental conditions is rationalized. Up-conversion to 2H(2)9/2, which is not due to two-photon absorption, is reported for Cs2NaErCl6 under blue pulsed laser excitation. Trap emission from 2G9/2 defect sites has been observed under ultraviolet excitation. A preliminary investigation has been made of the electronic absorption spectra of Cs2NaErCl6 and 58 Kramers quartet and doublet levels have been assigned, with a further 18 levels uncertain. The energy-level fit to 58 levels with total degeneracy 180 has been performed with a mean deviation of 20.4 cm-1, which is improved to 16.8 cm-1 if an empirical correction to the diagonal reduced matrix element of U4 for the 2H(2) term is included. The average error is similar for the 18 uncertain levels (total degeneracy 52). A comparison is included with the energy-level parametrizations of other Er3+ systems.published_or_final_versio

4f-5d transitions of Pr3+ in elpasolite lattices

The 4f5d→4f2 emission spectra of Cs2MPrCl6 (M = Na,Li) and CS2NaYCl6:Pr3+ have been recorded at temperatures down to 10 K. The spectra of Pr3+ in the cubic host Cs2NaYCl6 are the most clearly resolved, and 15 transitions to terminal crystal field levels of symmetry representations Γ5g and Γ4g have been observed and assigned, thereby inferring that the symmetry representation of the lowest 4f5d crystal field level is Γ3u. Each transition is characterized by strong progressions in two totally symmetric vibrational modes. The relative displacement of the potential energy curves for the 4f2 and 4f5d crystal field levels, along the α1g internal mode coordinate, is small, being only about 5 pm. The 10-K ultraviolet absorption spectra of CS2NaYCl6:Pr3+ are assigned to transitions from the [3H4] Γ1g electronic ground state to terminal Γ4u crystal field levels of 4f5d. Nontotally symmetric gerade vibrational modes only provide minor intensity contributions. The large energy gap between the d-f emission and f-d absorption spectra of Pr3+ in the cubic elpasolite host is rationalized. The 8-K excitation spectra of Cs2NaPrCl6 and Cs2NaYCl6:Pr3+, excited by synchrotron radiation, show that the transitions to 4f5d fall into two groups. The energy levels and wave vectors of the (independent) 4f2 and 4f5d configurations of Pr3+ have been calculated using a model which includes spin-orbit coupling and crystal field and Coulomb interactions, as well as the configuration interaction of 4f2 with 4f6p. Using the eigenvector of the predominantly high-spin, lowest excited crystal field level of 4f5d, the emission intensities are reasonably well simulated. However, the refinement of the 4f2→4f5d absorption intensities requires a more detailed knowledge of the crystal field energy level scheme of 4f5d. The configuration interaction of 4f5d with 4f6s and 4f5g is discussed.published_or_final_versio

The use of sublimable chlorotricarbonyl bis(phenylimino)acenaphthene rhenium(I) complexes as photosensitizers in bulk-heterojunction photovoltaic devices

A series of sublimable substituted chlorotricarbonyl bis(phenylimino)acenaphthene rhenium(I) complexes was synthesized and used in the fabrication of photovoltaic devices. The hole and electron carrier mobilities of these complexes are in the order of 10-3 to 10-4 cm2 V-1 s-1. Heterojunction devices with CuPc/complex/C60 (CuPc = copper phthalocyanine) as the active layer and bulk heterojunction devices with complex:C60 as the active layer were fabricated. The rhenium complexes function as photosensitizer in the devices, and exhibit optical absorption in the region between 500 and 550 nm within which other components in the device do not absorb. Other devices with hole transport materials, exciton blocking materials, and different active layer thickness were also fabricated. Variation of substitution groups in the ligand did not show significant difference in device performance. The best power conversion efficiency of the devices was measured to be 1.29% under illumination of AM1.5 simulated solar light. © 2009 Elsevier B.V. All rights reserved.postprin

Enhancing photosensitivity of carbon nanotubes by modification with metal containing block copolymers

Session S3 - Nano- and Bio-systems: abstract no. O3-4Carbon nanotubes exhibit highly promising potentials in applications such as optoelectronics, advanced composites, sensing, and biomedics. They have been demonstrated to be the key materials in various optoelectronic devices such as field effect transistors, photo switching, light sensing, and light emitters. In order to disperse carbon nanotubes in solution, chemical modification of nanotube surface or surfactants have to be used. Here, we report the use of a multifunctional metal containing block copolymers for dispersing carbon nanotubes and modification of their photosensitivity....postprintThe 12th International Conference on Electronic and Related Properties of Organic Systems (ERPOS-12), Vilnius, Lithuania, 11-13 July 2011. In Abstract book of ERPOS-12, 2011, p. 2

Liver cancer immunoassay with magnetic nanoparticles and MgO-based magnetic tunnel junction sensors

This journal issue is proceedings of the 56th 56th Conference on Magnetism and Magnetic MaterialsSession DV - Sensors 2 (Poster Session): no. DV-07We have demonstrated the detection of alpha-fetoprotein (AFP) labeled with magnetic nanoparticles (MNPs) using MgO-based magnetic tunnel junction (MTJ) sensors. AFP is an important hepatic tumor biomarker and the detection of AFP has significant applications for clinical diagnostics and immunoassay for early-stage liver cancer indications. In this work, MgO-based MTJ sensors and 20-nm iron-oxide magnetic nanoparticles (MNPs) were used for detecting AFP antigens by a sandwich-assay configuration. The MTJ sensors with a sensing area of 4 × 2 μm 2 possess tunneling magnetoresistance (TMR) of 122 and sensitivity of 0.95/Oe at room temperature. The target AFP antigens of three concentrations were successfully detected, and the experimental data indicate that the resistance variations of the MTJ sensor increased with the AFP concentration ratios proportionally. These results demonstrate that MgO-based MTJ sensors together with MNPs are a promising biosensing platform for liver cancer immunoassay. © 2012 American Institute of Physics.published_or_final_versionThe 56th Conference on Magnetism and Magnetic Materials, Scottsdale, AZ., 30 October-3 November 2011. In Journal of Applied Physics, 2012, v. 111 n. 7, article no. 07E50

Knowledge and attitudes of university students toward pandemic influenza: a cross-sectional study from Turkey

<p>Abstract</p> <p>Background</p> <p>During an influenza pandemic, higher education institutions with large populations of young adults can become serious outbreak centers. Since outbreak management is essential to disease control, we aimed to examine university students' knowledge of and attitudes toward the pandemic influenza A/H1N1 and vaccination and other preventive measures.</p> <p>Methods</p> <p>A cross-sectional study was conducted among 402 first year university students at Yeditepe University in Istanbul, Turkey between 1^stand 30^thof November 2009. Data regarding socio-demographic characteristics of the students, perceptions, level of knowledge and attitudes toward influenza pandemic and prevention measures were collected by means of a self-administered questionnaire. The questionnaire was distributed by the students affiliated with SANITAS, a university club of students in health related sciences.</p> <p>Results</p> <p>25.1% (101/402) of the study group perceived their personal risk of influenza as "high", while 40.5% (163/402) perceived it as "moderate", 20.6% (107/402) viewed it as "low" and 7.7% (31/402) indicated that it was "unknown". The risk perception of males was significantly lower than that of females (p = 0.004) and the risk perception among the students of health sciences was significantly lower than that of students of other sciences (p = 0.037). Within the study group, 72.1% (290/402) indicated that their main information source regarding H1N1 was the mass media. Health sciences students tended to rely more on the internet as an information source than other students (p = 0.015). The vast majority (92.8%; 373/402) of those interviewed indicated that they would not be vaccinated. The major concerns regarding vaccination had to do with the safety and side effects of the vaccine. Most of the participants (343/402, 85.3%) were carrying out one of prevention measures and the vast majority believed that hand washing, face mask and quarantina were effective measures for prevention.</p> <p>Conclusion</p> <p>The participants had enough knowledge about H1N1 pandemic about the disease although there were still gaps and confusions in some areas. In the future, when planning management strategies regarding pandemics or outbreaks in higher education institutions, new strategies should be developed to promote positive health behaviour among university students compatible with the international guidelines. Main information source is mass media, so it seems that new policies must be developed to attract attention of students to use different and more scientific-based information sources.</p

Liver cancer immunoassay with magnetic nanoparticles and MgO-based magnetic tunnel junction sensors

2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Chinese beliefs in luck are linked to gambling problems via strengthened cognitive biases:A mediation test

10.1007/s10899-017-9690-6Journal of gambling studies3341325-133

Conjugated polymers with pendant ruthenium dyes for photovoltaic applications

Different conjugated polymers attached with ruthenium terpyridine trithiocyanato complexes were synthesized. The conjugaed main chains were based on poly(phenylenevinylene), poly(phenylenethiophene), and poly(fluorenethiophene). Introduction of these ruthenium dye molecules greatly enhance the optical absorption of these polymers in the visible region, spanning from 400 to 700 nm. The optical absorption in these polymers mainly resulted from two electronic transitions: the π-π* transition of the conjugated polymer and the d-π;* metal-to-ligand charge transfer transition in the ruthenium complex. The hole and electron carrier mobilities of these polymers are in the order of 10-4 and 10-8 cm2/Vs, respectively. The polymers are soluble in DMF due to the presence of ionic complexes, and can be fabricated into thin film by spin coating process. Simple heterojunction devices ITO/polymer/fullerene/Al were fabricated and the power conversion efficiencies were in the range between 0.08 to 0.5 % under simulated solar light (AM1.5) illumination.link_to_subscribed_fulltex