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We measured the absorption spectra of T-shaped quantum wires at room temperature using waveguide-transmission spectroscopy. A strong and narrow room-temperature one-dimensional-exciton absorption peak was observed, which indicates a peak modal absorption coefficient of 160 cm-1 per 20 wires with a Γ-factor of 4.3×10-3, a width of 7.2 meV, and strong polarization anisotropy. [ABSTRACT FROM AUTHOR]

Crystalline microporous Co11(HPO3)8(OH)6 nanowires have been synthesized through a soft hydrothermal reaction between red phosphor, KOH, and metal halides. These nanowires were found to have their main hexagonal channels along the long axis and a narrow distribution around 30–40 nm in diameter. The growth of the nanowires were found to initiate at Co(OH)2 nuclei. The length of the nanowires depends mainly on the hydrothermal reaction time and the amount of Co(OH)2 available at the nuclei to feed the growth of the nanowires. Blue shift of up to 85 nm was observed in UV-visible absorption spectra from the Co11(HPO3)8(OH)6 nanowires in comparing with that from the micro-size particle sample, giving an absorption edge deep in the ultraviolet region at about 255 nm or a bandgap Eg∼4.9 eV. [ABSTRACT FROM AUTHOR]

The absorption spectrum of the explosive 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) has been measured using a conventional Fourier transform infrared spectroscopy and by terahertz pulsed spectroscopy. Seven absorption features in the spectral range of 5–120 cm-1 have been observed and identified as the fingerprint of RDX. Furthermore, the spatial distribution of individual chemical substances including RDX, has been mapped out using reflection terahertz spectroscopic imaging in combination with component spatial pattern analysis. This is the terahertz spectroscopy and chemical mapping of explosives obtained using reflection terahertz measurement, and represents a significant advance toward developing a terahertz pulsed imaging system for security screening of explosives. [ABSTRACT FROM AUTHOR]

Relationship between nonlinear refractivity and two-photon absorption has been studied for PbO–SiO2 glasses using a nonlinear Kramers–Kronig relation. Nonlinear refractive indices, which are determined with z-scan measurements, are consistent with those which are calculated using the relation from two-photon absorption spectra. This consistency suggests that large intensity-dependent refractivity in this glass system arises from resonant two-photon electronic transitions from oxygen 2p to lead 6p states. [ABSTRACT FROM AUTHOR]

Real-time pump-probe imaging spectroscopy with femtosecond time resolution is demonstrated. This method allows real-time mapping of frequency- and time-resolved transient absorption of materials at once. We can clearly measure the image of the transient absorption spectra of β-carotene with wide temporal and spectral ranges in a short accumulation time. Since the typical accumulation time is about two orders of magnitude shorter than that by the conventional pump-probe technique, this method becomes a powerful spectroscopic tool to study ultrafast relaxation and dynamics on organic/biochemical materials, which easily undergo photofatigue after many repetitions of the pump-probe sequence. [ABSTRACT FROM AUTHOR]

We describe the implementation of optical absorption spectroscopy in which a Ti:sapphire pumped femtosecond optical parametric oscillator based on periodically poled lithium niobate was used as a broadband source to directly acquire a midinfrared absorption spectrum of methane gas. Fourier-transform spectroscopy was performed using the idler output from the optical parametric oscillator to directly acquire spectra spanning over 600 nm (14.4 THz or 480 cm-1) with around 3 nm (78 GHz or 2.6 cm-1) resolution. This approach combines the advantages of spectroscopy using broadband thermal sources with the high power and excellent beam quality of a mode-locked laser source. [ABSTRACT FROM AUTHOR]