Vibrational overtone spectroscopy of pyridine and related compounds

Snavely, D. L.; Overly, Joyce A.; Walters, Valerie A.

doi:10.1016/0301-0104(95)00282-0

Cited by 13 publications

(18 citation statements)

References 19 publications

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“…The vapor phase overtone spectra of pyridine in the CH stretching regions corresponding to Δ v CH = 4−7 are shown in Figures −4. The spectra of the Δ v CH = 3−6 regions agree with previously reported spectra, apart from changes in relative intensities. The absence of corrections in the earlier spectra 20 for variation in laser power during a scan is a likely explanation for these intensity differences.…”

Section: Resultssupporting

confidence: 90%

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CH Stretching Overtone Investigation of Relative CH Bond Lengths in Pyridine

Kjaergaard¹,

Proos²,

Turnbull³

et al. 1996

J. Phys. Chem.

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We have recorded the room temperature CH stretching overtone spectra of pyridine, both in the vapor and in the liquid phase. We have used intracavity laser photoacoustic as well as conventional near-infrared absorption spectroscopy to measure these overtone transitions. Peaks corresponding to three nonequivalent CH stretching local modes are assigned in the high-energy vapor phase spectrum, as opposed to previous investigations which assigned only two. Absolute oscillator strengths are obtained from the conventional spectra and relative oscillator strengths between the observed peaks within a given overtone from the photoacoustic spectra. Oscillator strengths are calculated with an anharmonic oscillator local mode model and ab initio dipole moment functions. In the high-energy vapor phase spectrum, we have assigned the three peaks based on comparisons with ab initio calculated bond lengths and accurate overtone intensity calculations. Our simple calculations, which contain no adjustable parameters, are in very good agreement with both the absolute and relative observed intensities.

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Section: Resultssupporting

confidence: 90%

“…We refer to the three nonequivalent CH bonds as CH o , CH m , and CH p for the ortho, meta, and para bonds, respectively. Previous studies of the CH stretching overtone spectra of pyridine have reported only two peaks at each overtone, both in the liquid and in the vapor phase spectra . Sørensen et al.…”

Section: Introductionmentioning

confidence: 97%

CH Stretching Overtone Investigation of Relative CH Bond Lengths in Pyridine

Kjaergaard¹,

Proos²,

Turnbull³

et al. 1996

J. Phys. Chem.

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“…Nevertheless, our results show that the ν(OH), ν(OD) and ν(CH) bands are broadened by relaxation or in other words by intramolecular vibrational energy redistribution. Similar observations were made for the ν(NH) vibration of pyrrole (13), for the ν(CH) vibrations of pyridine (24), for the ν(CH) and ν(CD) vibrations of benzene and partially deuterated ben- transitions from v = 5 to v = 9, observed in benzene, has been attributed to the change in efficiency of vibrational energy distribution and to other mechanisms such as the coupling of the local CH stretching modes with the bending modes occuring in highly vibrationally excited sates (27 ).…”

Section: Near-infrared Spectra Of 4-clphoh and 4-clphodsupporting

confidence: 78%

Near-Infrared Spectrum (3000–10 000 cm−1) of 4-Chlorophenol in Solution

Michalska

Роспенк

Czarnik-Matusewicz

et al. 2002

Journal of Molecular Spectroscopy

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“…In order to account for the specific regions that used to distinguish the samples from different cultivation areas, the first three PCs that explained 99.8% of the total variance were investigated to discuss in Figure 5 . PC1 had the highest correlation between 4800 cm −1 and 7200 cm −1 in spectrum, which related to O–H overtones [ 31 , 32 , 33 ]; PC2 had the highest correlation between 4200 cm −1 and 5200 cm −1 in spectrum, which related to stretch and deformation of C–O group [ 34 , 35 , 36 ]; PC3 had the highest correlation between 4800 cm −1 and 5200 cm −1 in spectrum, which related to interaction between O–H and aromatic ring [ 37 , 38 ]; These results could be concluded that the differences of chemical components including the phenolics and water might account for the classification of their geographical origin.…”

Section: Resultsmentioning

confidence: 99%

Discrimination of Gastrodia elata from Different Geographical Origin for Quality Evaluation Using Newly-Build Near Infrared Spectrum Coupled with Multivariate Analysis

Zuo

Deng

2018

Molecules

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Discrimination of Gastrodia elata (G. elata) geographical origin is of great importance to pharmaceutical companies and consumers in China. this paper focuses on the feasibility of near infrared spectrum (NIRS) combined multivariate analysis as a rapid and non-destructive method to prove its fit for this purpose. Firstly, 16 batches of G. elata samples from four main-cultivation regions in China were quantified by traditional HPLC method. It showed that samples from different origins could not be efficiently differentiated by the contents of four phenolic compounds in this study. Secondly, the raw near infrared (NIR) spectra of those samples were acquired and two different pattern recognition techniques were used to classify the geographical origins. The results showed that with spectral transformation optimized, discriminant analysis (DA) provided 97% and 99% correct classification for the calibration and validation sets of samples from discriminating of four different main-cultivation regions, and provided 98% and 99% correct classifications for the calibration and validation sets of samples from eight different cities, respectively, which all performed better than the principal component analysis (PCA) method. Thirdly, as phenolic compounds content (PCC) is highly related with the quality of G. elata, synergy interval partial least squares (Si-PLS) was applied to build the PCC prediction model. The coefficient of determination for prediction (Rp2) of the Si-PLS model was 0.9209, and root mean square error for prediction (RMSEP) was 0.338. The two regions (4800 cm−1–5200 cm−1, and 5600 cm−1–6000 cm−1) selected by Si-PLS corresponded to the absorptions of aromatic ring in the basic phenolic structure. It can be concluded that NIR spectroscopy combined with PCA, DA and Si-PLS would be a potential tool to provide a reference for the quality control of G. elata.

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Vibrational overtone spectroscopy of pyridine and related compounds

Cited by 13 publications

References 19 publications

CH Stretching Overtone Investigation of Relative CH Bond Lengths in Pyridine

CH Stretching Overtone Investigation of Relative CH Bond Lengths in Pyridine

Near-Infrared Spectrum (3000–10 000 cm−1) of 4-Chlorophenol in Solution

Discrimination of Gastrodia elata from Different Geographical Origin for Quality Evaluation Using Newly-Build Near Infrared Spectrum Coupled with Multivariate Analysis

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