Femtosecond pump probe spectroscopy is employed to study the photo-induced absorption feature in the single-walled carbon nanotube transient spectrum. The two advantages of the experiment, a chirality enriched sample ...Femtosecond pump probe spectroscopy is employed to study the photo-induced absorption feature in the single-walled carbon nanotube transient spectrum. The two advantages of the experiment, a chirality enriched sample and tuning the pump wavelength to the resonance of a specific nanotube species, greatly facilitate the identification of the photo-induced absorption signal of one tube species. It is found that a photo-induced absorption feature is located at one radial breathing mode to the blue side of the E11 state. This finding prompts a new explanation for the origin of the photo-induced absorption: the transition from the ground state to a phonon coupled state near the E ii state. The explanation suggests a superposition mechanism of the photo-bleach and photo-induced absorption signals, which may serve as a key to the interpretation of the complex pump probe transient spectrum of carbon nanotubes. The finding sheds some light on the understanding of the complex non-radiative relaxation process and the electronic structure of single-walled carbon nanotubes.展开更多
In-Pd-Co-SnO_(2) composite nanofibers have been synthesized by an electrospinning method and characterized by xray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).Micros...In-Pd-Co-SnO_(2) composite nanofibers have been synthesized by an electrospinning method and characterized by xray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).Microsensors with a tiny area of 1 × 1 mm^(2) are fabricated by spinning the nanofibers on sensor substrates.Excellent CH4 sensing properties are found based on the micro-sensors.The sensitivity is up to 13 when the sensors are exposed to 10ppm CH4 at 140℃,and the response and recovery times are about 8 and 14s,respectively.High selectivity,good stability,and low power-consumption are also observed in the investigation.展开更多
文摘Femtosecond pump probe spectroscopy is employed to study the photo-induced absorption feature in the single-walled carbon nanotube transient spectrum. The two advantages of the experiment, a chirality enriched sample and tuning the pump wavelength to the resonance of a specific nanotube species, greatly facilitate the identification of the photo-induced absorption signal of one tube species. It is found that a photo-induced absorption feature is located at one radial breathing mode to the blue side of the E11 state. This finding prompts a new explanation for the origin of the photo-induced absorption: the transition from the ground state to a phonon coupled state near the E ii state. The explanation suggests a superposition mechanism of the photo-bleach and photo-induced absorption signals, which may serve as a key to the interpretation of the complex pump probe transient spectrum of carbon nanotubes. The finding sheds some light on the understanding of the complex non-radiative relaxation process and the electronic structure of single-walled carbon nanotubes.
基金Supported by the Natural Science Basic Research Plan of Shanxi Province under Grant No 2010011026-2.
文摘In-Pd-Co-SnO_(2) composite nanofibers have been synthesized by an electrospinning method and characterized by xray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).Microsensors with a tiny area of 1 × 1 mm^(2) are fabricated by spinning the nanofibers on sensor substrates.Excellent CH4 sensing properties are found based on the micro-sensors.The sensitivity is up to 13 when the sensors are exposed to 10ppm CH4 at 140℃,and the response and recovery times are about 8 and 14s,respectively.High selectivity,good stability,and low power-consumption are also observed in the investigation.