Rotational dynamics of Li ions encapsulated in C cages at low temperatures.

Li ions encapsulated in fullerene C cages (Li@C) are expected to be suitable as molecular switches that respond to local electric fields. In this study, the rotational dynamics of Li ions in C cages at low temperatures are experimentally revealed for the first time using terahertz absorption spectroscopy. In crystalline [Li@C](PF), the Li ion rotates in the carbon cage even at 150 K.

Analytical solutions of electromagnetic waves in focusing and magnifying cylindrical hyperlenses: Green's function approach.

The analytical solutions of the electromagnetic waves in the inhomogeneous cylindrical hyperlens (CH) comprising concentric cylindrical layers (CCLs) with multiple point sources located either outside the structure in the focusing process or inside the core in the magnifying process are obtained by means of Green's function analysis. The solutions are consistent with FDTD simulation in both processes. The sub-wavelength focal spot λ/16.

THz emission characteristics from p/n junctions with metal lines under non-bias conditions for LSI failure analysis.

We have investigated the characteristics of THz emissions from p/n junctions with metallic lines under non-bias conditions. The waveforms, spectra, and polarizations depend on the length and shape of the lines. This indicates that the transient photocurrents from p/n junctions flow into the metallic lines that emit THz waves and act as an antenna.

High-resolution time-of-flight terahertz tomography using a femtosecond fiber laser.

High-resolution tomographic imaging is demonstrated using a reflection-type terahertz time-domain spectroscopy. To realize a practical system for general use, a robust all-fiber laser was used as the pump light source. Broadband terahertz waves were generated with the combination of optical pulses compressed to 17 fs using optical fibers and a DAST crystal.

Generation and detection of broadband coherent terahertz radiation using 17-fs ultrashort pulse fiber laser.

We describe the generation and detection of broadband terahertz radiation using an all-fiber laser. Optical pulses from a mode-locked fiber laser oscillator are compressed using nonlinear and dispersion effects induced in optical fibers, and 17-fs optical pulses with 170-kW peak power are generated at the wavelength region around 1.5 microm.

Phenolic compounds from sugarcane molasses possessing antibacterial activity against cariogenic bacteria.

During the course of our research into the use of cane by-products from sugar manufacturing, we have studied the isolation and structural determination of bioactive compounds present in sugarcane molasses. In this study, dehydrodiconiferylalcohol-9'-O-beta-D-glucopyranoside (1) and isoorientin-7, 3'-O-dimethyl ether (2) were isolated as antibacterial active compounds against cariogenic bacteria. Their structures were elucidated by (1)H-NMR, (13)C-NMR and ESI-MS.

1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity and tyrosinase inhibitory effects of constituents of sugarcane molasses.

In the course of our work into the use of cane by-products, we have studied the isolation and structural determination of bioactive compounds in sugarcane molasses. In this study, three stereo isomers of syringyl glycerol 3'-O-beta-D-glucopyranoside, three stereo isomers of guaiacyl glycerol 3'-O-beta-D-glucopyranoside, a syringyl glycerol 2'-O-beta-D-glucopyranoside, tachioside and a 2,3-dihydro-3,5-dihydroxy-6-methyl-4-(H)-pyran-4-one (DDMP) were isolated from the 25% methanol eluate by Amberlite XAD-2 column chromatography of sugarcane molasses. The structures of these compounds were determined on the basis of spectroscopic evidence.

Component spatial pattern analysis of chemicals by use of two-dimensional electro-optic terahertz imaging.

We demonstrate a method of chemical mapping by using the transillumination terahertz (THz) images obtained by two-dimensional electro-optic THz imaging. The images and spectral data were measured between 0.1 and 1.

Imaging of large-scale integrated circuits using laser-terahertz emission microscopy.

We present the redesign and improved performance of the laser terahertz emission microscope (LTEM), which is a potential tool for locating electrical failures in integrated circuits. The LTEM produces an image of the THz waves emitted when the circuit is irradiated by a femtosecond laser; the amplitude of the THz emission is proportional to the local electric field. By redesigning the optical setup and improving the spatial resolution of the system to below 3 microm, we could extend its application to examining of large-scale integration circuits.

Terahertz imaging system based on a backward-wave oscillator.

We present an imaging system designed for use in the terahertz range. As the radiation source a backward-wave oscillator was chosen for its special features such as high output power, good wave-front quality, good stability, and wavelength tunability from 520 to 710 GHz. Detection is achieved with a pyroelectric sensor operated at room temperature.

Laser terahertz-emission microscope for inspecting electrical faults in integrated circuits.

A laser terahertz-emission microscope (LTEM) system is proposed and developed for inspecting electrical faults in integrated circuits (IC). We test a commercial operational amplifier while the system is operating. Two-dimensional terahertz-emission images of the IC chip are clearly observed while the chip is scanned with a femtosecond laser.