Improving Spectroscopic Techniques by a Scanning Multichannel Method

Abstract

The conventional optical multichannel technique (MT) has improved optical spectroscopy, in comparison to single-channel methods, by at least an order of magnitude in measurement time at the same signal-to-noise ratio. In this work we show that some disadvantages (e.g., limited range of the recorded spectra, different noise and sensitivity of each detection element, and fixed spectral distance of the detection elements) can be excluded by using what we call the scanning multichannel technique (SMT). A calculation of the measurement time for characteristic single-channel and multichannel detectors results in the fact that SMT is, like MT, an order of magnitude faster than the single-channel technique (SCT). In some particular cases SMT results in measurement times shorter than those for MT. We conclude that SMT combines the advantages of MT and SCT. Moreover, measurements of sharp spectral lines made it evident that SMT also improves the reproducibility of the spectrometer used and increases the accuracy of the recorded spectra. The SMT method is not only restricted to optical spectroscopy but can be universally applied to all spectroscopic methods where multichannel detection is used.

Probing antiaromaticity: resonance Raman investigation of a series of differently substituted boroles

“…The RR spectra were recorded with a liquid-nitrogen-cooled CCD camera (Photometrics, model SDS 9000) and acquired with the scanning multichannel technique (SMT). [29] For each spectral window at each excitation wavelength, the integration time was 25 s. We applied a 15-point baseline correction in the depicted range (1800-800 cm −1 ) to all raw data (both experimental setups).…”

Li2Si3O7: Crystal structure and Raman spectroscopy

“…Confocal pinhole was set to 1000 mm. Spectra were recorded unpolarised in scanningmode [25,26]. All spectra were background corrected by subtraction of line segments and fitted to Gauss-Lorentz functions.…”

Polarization‐sensitive CARS spectroscopy on free‐base porphyrins: coproporphyrin I tetramethyl ester

“…The signal was focused on the entrance slit of a double monochromator (Spex 1404, 2400 gr/mm), the slit being kept at a resolution of ¾0.7 cm 1 , and detected with a CCD camera (Photometrics SDS9000) by making use of the scanning multichannel technique (SMT). 40 The polarization of the excitation and the signal beam were controlled by mounting a Glan-Thompson polarizer and a double Fresnel rhomb before the sample and another~ Glan-Thompson polarizer behind the sample. Both polarizer crystals, the first one serving as pre-polarizer and the second one as analyzer, remain in fixed position during the measurements, while the desired parallel and perpendicular orientation of the polarization is adjusted by means of the Fresnel rhomb.…”