Fluorescence Quenching of Alpha-Fetoprotein by Gold Nanoparticles: Effect of Dielectric Shell on Non-Radiative Decay

Fluorescence quenching spectrometry was applied to study the interactions between gold colloidal nanoparticles and alpha-fetoprotein (AFP). Experimental results show that the gold nanoparticles can quench the fluorescence emission of adsorbed AFP effectively. Furthermore, the intensity of fluorescence emission peak decreases monotonously with the increasing gold nanoparticles content. A mechanism based on surface plasmon resonance–induced non-radiative decay was investigated to illuminate the effect of a dielectric shell on the fluorescence quenching ability of gold nanoparticles. The calculation results show that the increasing dielectric shell thickness may improve the monochromaticity of fluorescence quenching. However, high energy transfer efficiency can be obtained within a wide wavelength band by coating a thinner dielectric shell

Angle dependent magnetoresistance oscillation study of the Fermi surface of β″-(BEDT-TTF)2AuBr2

Angle dependent magnetoresistance oscillations (AMRO) have been studied for the charge-transfer salt β″-(BEDT-TTF)2AuBr2. The temperature range 1.5 K-4.2 K and field region 0.5 T-30 T have been explored. A series of AMRO peaks originating from a approx.40 T elliptical quasi-two-dimensional (Q2D) Fermi surface (FS) pocket have been observed at all fields. The measured orientation of this pocket is in good agreement with band structure calculations. Above a field of approx.10 T a second series of (Q2D) AMRO peaks emerge, indicating a field-induced reconstruction of the FS. It is proposed that this results from a shifting of the nesting vector of the spin density wave which is believed to be present in this material. The high field series of peaks correspond to a approx.222 T elliptical FS pocket with major axis aligned along the direction in which band structure calculations predict Q1D Fermi sheets. It is thus attributed to imperfect nesting of the Q1D FS sheets

Angle dependent magnetoresistance oscillation study of the Fermi surface of beta''-(BEDT-TTF)(2)AuBr2

Angle dependent magnetoresistance oscillations (AMRO) have been studied for the charge-transfer salt beta ''-(BEDT-TTF)(2)AuBr2. The temperature range 1.5 K-4.2 K and field region 0.5 T-30 T have been explored. A series of AMRO peaks originating from a similar to 40 T elliptical quasi-two-dimensional (Q2D) Fermi surface (FS) pocket have been observed at all fields. The measured orientation of this pocket is in good agreement with band structure calculations. Above a field of similar to 10 T a second series of(Q2D) AMRO peaks emerge, indicating a field-induced reconstruction of the FS. It is proposed that this results from a shifting of the nesting vector of the spin density wave which is believed to be present in this material. The high field series of peaks correspond to a similar to 222 T elliptical FS pocket with major axis aligned along the direction in which band structure calculations predict Q1D Fermi sheets. It is thus attributed to imperfect nesting of the Q1D FS sheets

Muon spin rotation studies of the vortex lattice in κ-(ET)₂Cu(NCS)₂

Angle dependent magnetoresistance oscillations (AMRO) have been studied for the charge-transfer salt alpha-(BEDT-TTF)(2)KHg(SCN)(4). This material possesses a spin-density-wave (SDW) groundstate exhibiting AMRO with pronounced minima attributable to quasi-one-dimensional (Q1D) sections of Fermi surface (FS). Increasing the temperature or the magnetic field produces a change in the AMRO with the strong minima disappearing while pronounced peaks simultaneously evolve. These maxima are ascribable to a Q2D FS pocket. The change in form of the AMRO is thus associated with a reordering of the FS. This is brought about by removal of the SDW state causing reversion of the FS to the form close to that predicted by bandstructure calculations. The phase boundary between these two regimes has been tracked using AMRO from the high temperature limit to the high field limit for the first time and the shape of the Q2D sections of FS derived

Magnetic-field dependent Fermi surfaces in quasi-2D organic conductors

Contains fulltext : 28188.pdf (publisher's version ) (Open Access

Magneto-optical and magneto-transport studies of electron- electron interactions in organic conductors using fields up to 50T

Contains fulltext : 112791.pdf (publisher's version ) (Open Access

High-field Magnetotransport Studies of (et)2mhg(scn)4 Salts (m=k, Nh4)

The angle dependence of the magnetoresistance (MR) of (ET)2(SCN)4 (M=K,NH4) has been measured in steady magnetic fields up to 50 T. In (ET)2KHg(SCN)4 We observe two SdH frequencies in the MR below the resistive ''kink'' feature at 22 T, and different values of g*m* above and below the ''kink''; we propose that these effects result from antiferromagnetic ordering between the conducting planes. In (ET)2NH4Hg(SCN)4 we have found that both the frequency of the Shubnikov-de Haas (SdH) oscillations and the effective mass of the carriers vary to a high degree of accuracy as 1/cos(theta) (theta is the angle between the field and the normal to the conducting layers) as expected for a quasi two-dimensional system, and in contrast to a previous study by others. Finally we comment on the validity of the ''Harmonic Ratio'' method for measuring effective masses