Fourier transform infrared spectroscopy

About: Fourier transform infrared spectroscopy is a research topic. Over the lifetime, 48250 publications have been published within this topic receiving 1134369 citations.

Fourier transform spectroscopy with a laser frequency comb

Abstract: Molecular fingerprinting using absorption spectroscopy is a powerful analytical method, particularly in the infrared, the region of intense spectral signatures Fourier transform spectroscopy—the widely used and essential tool for broadband spectroscopy—enables the recording of multi-octave-spanning spectra, exhibiting 100 MHz resolution with an accuracy of 1 × 10−9 and 1 × 10−2 in wavenumber and intensity determination, respectively Typically, 1 × 106 independent spectral elements may be measured simultaneously within a few hours, with only average sensitivity Here, we show that by using laser frequency combs as the light source of Fourier transform spectroscopy it is possible to record well-resolved broadband absorption and dispersion spectra in a single experiment, from the beating signatures of neighbouring comb lines in the interferogram The sensitivity is thus expected to increase by several orders of magnitude Experimental proof of principle is here carried out on the 15-µm overtone bands of acetylene, spanning 80 nm with a resolution of 15 GHz Consequently, without any optical modification, the performance of Fourier spectrometers may be drastically boosted By using an optical frequency comb as the light source for Fourier transform spectroscopy, scientists show that well-resolved broadband absorption and dispersion spectra can be recorded in a single experiment, providing sensitive detection of multiple molecular species over a broad spectral window

Hydrophobic cellulose nanocrystals modified with quaternary ammonium salts

Abstract: An environmentally friendly procedure in aqueous solution for the surface modification of cellulose nanocrystals (CNCs) using quaternary ammonium salts via adsorption is developed as inspired by organomodified layered silicates. CNCs with a high carboxylate content of 1.5 mmol g−1 were prepared by a new route, direct hydrochloric acid hydrolysis of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose from a softwood pulp, and characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). Four quaternary ammonium cation surfactants bearing long alkyl, phenyl, glycidyl, and diallyl groups were successfully used to modify CNCs carrying carboxylic acid groups as characterized by Fourier transform infrared spectroscopy (FTIR). The modified CNCs can be redispersed and individualized in an organic solvent such as toluene as observed by scanning transmission electron microscopy (STEM). One may envision removing excess surfactant to obtain CNC with a monolayer of surfactant. The toluene suspension of the modified CNCs showed strong birefringence under crossed polars but no further chiral-nematic ordering was observed. The model surface prepared by the CNCs modified with quaternary ammonium salts bearing C18 alkyl chains showed a significant increase in water contact angle (71°) compared to that of unmodified CNCs (12°). This new series of modified CNCs can be dried from solvent and have the potential to form well-dispersed nanocomposites with non-polar polymers.

A Novel Wet Chemistry Approach for the Synthesis of Hybrid 2D Free-Floating Single or Multilayer Nanosheets of MS2@oleylamine (M═Mo, W)

Abstract: A new wet chemistry approach, based on low-temperature (360 °C) decomposition in oleylamine of single-source precursors containing both metal and sulfur, is proposed for the production of stable free-standing nanosheets of MoS2 and WS2. The one-pot synthesis permits high-quality 2D nanosheet crystals of MoS2 and WS2 to be obtained with a modular number of nanolayers for units. The layered materials obtained are covered by a dynamic protective coating of oleylamine that stabilizes the suspension, avoids aggregation and oxidation phenomena, and could be easily functionalized with other molecules or nanosystems to introduce new properties to the hybrid organic–inorganic nanocomposite. The reaction products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), attenuated total reflectance Fourier transform infrared spectroscopy (ART-FTIR), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis coupled with mass s...