Relative intensity correction of Raman optical activity spectra facilitates extending the spectral region

Abstract

Using home‐built Raman optical activity (ROA) spectrometer and a relative intensity correction for different instrument responses, we report ROA spectra beyond the traditionally utilized spectral region of 200–2500 cm−1. With three different interchangeable gratings covering partially overlapping spectral regions, we can study ROA in the whole region of fundamental molecular vibrations (150–4000 cm−1). Complete panoramic spectra are assembled from subparts collected with different gratings after a relative intensity correction based on the National Institute of Science and Technology standards known from the analogous application in Raman and fluorescence spectroscopy. Using this setup, we report the still little known ROA from C–H and C–D stretching region of the testing substances α‐pinene and a tricyclic spirodilactam. The intensity‐corrected experimental data were compared with calculated ROA and Raman spectra of these substances both with and without anharmonic corrections. A comparison revealed that above 1200 cm−1, the anharmonic correction provides a clear improvement of the agreement. While the calculation of Raman spectra achieves already good accuracy, the analogous ROA calculations still need further development. Copyright © 2014 John Wiley & Sons, Ltd.

Detection of Sugars via Chirality Induced in Europium(III) Compounds

“…For example, fructose induces a strong multiband pattern in the EuEDTA ion with peaks at 1696(−), 1746 (+), 1780 (−), 1839(−), 1897 (+), 1999 (+), 2052 (−), 2133 (+), and 2416 (−) cm –1 . The last band (2416 cm –1 ) is close to the operational limit of the spectrometer, and its intensity might be attenuated by the limited sensitivity of the CCD detector . For EuCl 3 , the fructose ROA/CPL spectral pattern is much simpler and the signal is weaker (dominated by 1823 (−) and 2055 (+) cm –1 bands) than for EuEDTA.…”

“…The last band (2416 cm −1 ) is close to the operational limit of the spectrometer, and its intensity might be attenuated by the limited sensitivity of the CCD detector. 48 For EuCl 3 , the fructose ROA/CPL spectral pattern is much simpler and the signal is weaker (dominated by 1823 (−) and 2055 (+) cm −1 bands) than for EuEDTA. For mannose, the situation is rather opposite; i.e., there is a strong, about six-band signal with EuCl 3 and a weaker 1808(+)/1888(−) cm −1 "couplet" (two strong close bands of similar intensities but of opposite signs) dominating the EuEDTA spectrum.…”

Europium (III) as a Circularly Polarized Luminescence Probe of DNA Structure

“…The TL band around 1530 cm −1 ( 5 D 0 7 F 0 transition) does not show measurable CPL except for the case of DNA 2 (1533 cm −1 ). Although the bands above 2450 cm −1 (>610 nm) ( 5 D 0 7 F 2 transition) are not accessible with our instrument, they could be measured with extended-range custom-made ROA spectrometers 18,19 , thus this is not a general limitation of the method.…”

Simulation of Raman and Raman optical activity of saccharides in solution

“…The spectra were finally normalized to the accumulation time and we performed a relative intensity correction. 23 Spectra of mb-glc were taken from Cheeseman et al 13…”