Fourier transform spectroscopy

About: Fourier transform spectroscopy is a research topic. Over the lifetime, 5418 publications have been published within this topic receiving 134133 citations.

Mid-infrared dual-comb spectroscopy with 2.4 μm Cr2+:ZnSe femtosecond lasers

Abstract: The mid-infrared part of the electromagnetic spectrum is the so-called molecular fingerprint region because gases have tell-tale absorption features associated with molecular rovibrations. This region can be for instance exploited to detect small traces of environmental and toxic vapors in atmospheric and industrial applications. Novel Fourier-transform spectroscopy without moving parts, based on time-domain interferences between two comb sources, can in particular benefit optical diagnostics and precision spectroscopy. To date, high-resolution and -sensitivity proof-of-principle experiments have only been reported in the near-infrared region where frequency-comb oscillators are conveniently available. However, as most of the molecular transitions in this region are due to weak overtone bands, this spectral domain is not ideal for sensitive and rapid detection. Here we present a proof-of-principle experiment of frequency-comb Fourier-transform spectroscopy with two Cr2+:ZnSe femtosecond oscillators directly emitting in the 2.4 μm mid-infrared region. The acetylene absorption spectrum in the region of the $ u_{1}+ u_{5}^{1}$ band, extending from 2370 to 2525 nm, could be recorded within a 10 μs acquisition time without averaging with 12 GHz resolution.

Two-color two-dimensional Fourier transform electronic spectroscopy with a pulse-shaper.

Abstract: We report two-color two-dimensional Fourier transform electronic spectroscopy obtained using an acousto-optic pulse-shaper in a pump-probe geometry. The two-color setup will facilitate the study of energy transfer between electronic transitions that are widely separated in energy. We demonstrate the method at visible wavelengths on the laser dye LDS750 in acetonitrile. We discuss phase-cycling and polarization schemes to optimize the signal-to-noise ratio in the pump-probe geometry. We also demonstrate that phase-cycling can be used to separate rephasing and nonrephasing signal components.

Miniaturized time-scanning Fourier transform spectrometer based on silicon technology

Abstract: We present a miniaturized Fourier transform spectrometer (FTS) based on optical microelectromechanical system technology The FTS is a Michelson interferometer with one scanning mirror A new type of electrostatic comb drive actuator moves the mirror We have measured a nonlinearity of the driving system of ±05 µm for a displacement of 385 µm A method is presented to correct the spectrum to get rid of the nonlinearity The driving reproducibility is ±25 nm The measured resolution of the spectrometer after the phase correction is 6 nm at a wavelength of 633 nm

Structural and electronic transitions in polyaniline: A Fourier transform infrared spectroscopic study

Abstract: Fourier transform infrared (FTIR) spectroscopic studies are carried out on different, potentiometric well defined oxidation states of polyaniline in aqueous acidic and organic electrolytes. During the oxidation process ring structures transform from benzenoid into quinoid states. The fully reduced state of polyaniline shows differences in the anion contents in acidic and organic electrolytes. The 400 mV vs saturated calomel electrode (SCE) oxidized state has the maximum number of the intercalated anions in aqueous acidic media in accordance with supporting potentiometric titration experiments. This conducting form of polyaniline shows similar FTIR spectra in organic as well as in acidic media. For the oxidized state at 800 mV vs SCE, a deintercalation of anions in aqueous acidic, or further intercalation in organic electrolyte is observed. Beyond 800 mV vs SCE, polyaniline shows degradation processes in aqueous acidic media which are found to proceed via formation of benzoquinone‐like structures and finally result in a complete dissolution of the polymer.