Two modes of electroluminescence from single‐walled carbon nanotubes

The electroluminescence from single‐walled carbon nanotube field effect transistors is spectrally resolved, and shows two distinct modes of light emission. The vast majority of nanotubes have spectrally broad emission consistent with the spectrum of blackbody radiation. Much more rarely, superposed on the broad emission is a single narrow (<50 meV) peak which is consistent with expectation for electron–hole recombination. The narrow emission is strong even at lower biases and in general has greater peak intensity than the broadband emission. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gas monitoring in the process industry using diode laser spectroscopy

2 , CO, NH₃, HCl and HF are described together with measurements from several installations. The monitors show continuous measurements with fast response and good sensitivity, all of which is difficult to obtain with conventional techniques such as wet chemical analysis. Received: 19 March 1998/Revised version: 2 June 1998     

The mechanism of nanostructuring upon nanosecond laser irradiation of a STM tip

Received: 20 April 1998/Accepted: 2 June 1998     

Frictional and atomic-scale study of C60 thin films by scanning force microscopy

Scanning force microscopy (SFM) was employed to characterize C₆₀ island films in an ultra-high vacuum (UHV). The initial growth stage of C₆₀ on NaCl cleavage faces and nanotribological properties of this solid lubricant are investigated. In comparison to the NaCl(001) face, higher friction is measured on the C₆₀ islands, resulting in a ratio of friction of 13 for NaClC₆₀. The friction coefficient of the (111) oriented C₆₀ island is determined to be 0.15±0.05. High-resolution SFM images reveal the hexagonal lattice of the unreconstructed (111) top surfaces and the overgrowth relationships of the C₆₀ islands.     

Spectroscopy in our age

The development of modern spectroscopy is summarized from Bunsen’s detection of atoms as the beginning of spectral analysis to modern molecular spectroscopies including new high resolution techniques for molecular ions. Recent experiments involving long range charge migration in peptides and proteins are outlined. Received: 2 October 2000 / Published online: 11 October 2000     

Radio-frequency (RF) studies of the magneto-dielectric composites: Cr0.75Fe1.25O3 (CRFO)-Fe0.5Cu0.75Ti0.75O3 (FCTO)

This paper concerns a study about the electrical properties of Cr_0.75Fe_1.25O₃ (CRFO)/Fe_0.5Cu_0.75Ti_0.75O₃ (FCTO) magneto-dielectric composites. These compounds were prepared by the conventional solid-state reaction synthesis. The samples synthesized, as well their two-phase composites [Cr_0.75Fe_1.25O₃]_Z-[Fe_0.5Cu_0.75Ti_0.75O₃]_100−Z (Z=17, 34, 50, 66, 83), were characterized by X-ray powder diffraction technique (XRD). Rietveld's method was employed to verify the quantitative phase abundances in the composites’ and their theoretical densities, which were compared with the experimental densities (pycnometer method).To predict the effect of the phases in the composites effective dielectric function (κ), traditional dielectric mixing models such as parallel, series, and Lichtenecker's model were observed. An alternative approach, a sigmoidal fitting function based on the Boltzmann equation, was proposed to fit the experimental data.     

Dipolar and magnetic ordering in Nd-modified BiFeO3 nanoceramics

The polycrystalline samples of Bi_1−xNd_xFeO₃ (BNFO) with x=0, 0.05, 0.1, and 0.15 were prepared by a chemical route (metal ion complex precursor solution method). A systematic change in crystal structure from rhombohedral to tetragonal on increasing Nd substitution was observed. The reduction of low-frequency dispersion in permittivity and loss pattern due to Nd substitution in BiFeO₃ (BFO) was observed in its dielectric response curve. The loss tangent (tan δ) was found to be reduced on increased Nd concentration in BNFO. Dielectric anomaly near the reported Neel temperature of BFO and peaks in all the BNFO samples were observed in the permittivity vs. temperature graph. Significant opening in the room temperature M–H loop was observed on Nd substitution, which was more prominent for higher concentration of Nd.     

Present and future developments of SPM systems as mass storage devices

2 . Besides a high data density, a high data rate is an important requirement for a mass storage device. To overcome the problem of the low relative velocity between tip and sample for all commercial scanning probe microscopy (SPM) devices, we have developed a high speed SCM prototype which has the potential to reach data rates of Mbit/s. Received: 27 March 1998     

Spin-spiral and domain wall structures in monolayer Fe/W(1 1 0)

The stability of spin-spiral and domain wall structures in an Fe monolayer on a W(1 1 0) substrate is theoretically investigated. By analyzing the exchange parameters obtained from first principles total energy calculations, we find that a competition between the nearest-neighbor ferromagnetic and long-distant antiferromagnetic exchange interactions leads to a stabilization of the spin-spiral structures. When the strong magnetocrystalline anisotropy (MCA) arising from the Fe/W(1 1 0) interface is introduced, however, the formation of the spin-spiral structures is suppressed and the ground state appears to be the ferromagnetic state—as observed in experiments. In addition, the strong MCA is found to play a key role in determining the domain wall structures.