排序方式: 共有33条查询结果,搜索用时 15 毫秒
31.
Vieira HS Andrada DM Mendonça R Santos AP Martins MD Macedo WA Gorgulho HF Pimenta LP Moreira RL Jorio A Pimenta MA Furtado CA 《Journal of nanoscience and nanotechnology》2007,7(10):3421-3430
A classical protocol widely used in organic chemistry of aromatic and polyaromatic molecules has been successfully applied in this work for the decarboxylation of oxidized single-wall carbon nanotube (SWNT) to rend C-H SWNT derivatives. SWNT produced by arc discharge method have been oxidized during a purification process using strongly oxidant agents, such as hydrogen peroxide and nitric acid. The decarboxylation of oxidized SWNT has been conduced with copper(I) oxide in a 50:50 solution of N-methylpyrrolidone and quinoline. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and acid-base potentiometric titration analyses were carried out to characterize quali and quantitatively the changes in the chemical environment on the SWNT surface in each step of the purification and the decarboxylation process. Those techniques showed the appearance of mainly carboxylic and phenolic groups after the purification process and the disappearance of the carboxylic groups after the decarboxylation reaction. Fourier transform infrared spectroscopy analysis indicated also the formation of aliphatic and aromatic C-H groups. X-ray photoelectron spectroscopy and potentiometric titration results determined an efficiency higher than 90% for our decarboxylation procedure. The purity and structural quality of the SWNT sample used in the decarboxylation process were evaluated by thermogravimetry and Raman spectroscopy. Thermogravimetric analysis identified a purified sample with approximately 80 wt% of SWNT, in fractions distributed in highly structured SWNTs (25 wt%), with distribution in composition, length and structural quality (35 wt%) and with very defective and short tubes (25 wt%). The damages on the purified SWNT walls were characterized by the Raman scattering analysis. 相似文献
32.
Qian H Araujo PT Georgi C Gokus T Hartmann N Green AA Jorio A Hersam MC Novotny L Hartschuh A 《Nano letters》2008,8(9):2706-2711
We studied the local optical response of semiconducting single-walled carbon nanotubes to wrapping by DNA segments using high resolution tip-enhanced near-field microscopy. Photoluminescence (PL) near-field images of single nanotubes reveal large DNA-wrapping-induced red shifts of the exciton energy that are two times higher than indicated by spatially averaging confocal microscopy. Near-field PL spectra taken along nanotubes feature two distinct PL bands resulting from DNA-wrapped and unwrapped nanotube segments. The transition between the two energy levels occurs on a length scale smaller than our spatial resolution of about 15 nm. 相似文献
33.
Nesrine Ebrahim Hajir A. Al Saihati Ola Mostafa Amira Hassouna Sameh Abdulsamea Eman Abd El Aziz M. El Gebaly Nashwa Hassan Abo-Rayah Dina Sabry Mohamed El-Sherbiny Abdelmonem G. Madboly Noha Ibrahim Hussien Raja El Hasnaoui Saadani Hasnaa Ali Ebrahim Omnia A. M. Badr Nehal M. Elsherbiny Rabab F. Salim 《International journal of molecular sciences》2022,23(11)