Raman excitation profile of diphenylamine

Sett, Pinaky; De, Avik; Chattopadhyay, S.; Mallick, Prabal Kumar

doi:10.1016/s0301-0104(01)00571-7

Cited by 28 publications

(40 citation statements)

References 32 publications

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“…Taking into account that the asymmetric molecular conformation obtained at the RHF/6-31G** level of theory is very close in energy to the symmetric structure (C 2 ), the assignment of frequencies was limited to this calculation that is qualitatively is very similar to the assignment of frequencies at the B3LYP/6-31G** level of theory. The calculated frequencies (after scaling) and IR intensities fit both experimental [7,20324] and calculated by other authors [11].…”

supporting

confidence: 74%

“…The IR spectra of diphenylamine in the gas phase are lacking, but those in solution (CCl 4 ), liquid, and crystal are available [7,20324]. The crystal spectrum is more complicated and in general is similar to the spectra in solution and liquid (melt at 367 K).…”

mentioning

confidence: 99%

“…The vibration spectra of diphenylamine have been considered in [7,11313,20322]. Thus, Sett et al [7] preliminary assigned experimental IR and Raman frequencies in terms of C 2v symmetry, but did not calculate frequencies.…”

mentioning

confidence: 99%

“…Thus, Sett et al [7] preliminary assigned experimental IR and Raman frequencies in terms of C 2v symmetry, but did not calculate frequencies. Choi and Kertesz [11] performed full assignment of vibration frequencies on the basis of RHF/6-31G* ab initio calculations and found that the experimental IR and Raman intensities are well described by an asymmetric molecular model (C 1 ).…”

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confidence: 99%

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Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

et al. 2005

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Geometric parameters of the diphenylamine molecule were determined by gas-phase electron diffraction and quantum-chemical calculations. By gas-phase electron diffraction, the molecule has an asymmetric structure with torsion angles about N3C bonds of 345.6(23)o and 173.4(46)o, which agrees with RHF/6-31G** calculations. Density functional theory (DFT) calculations at the B3LYP/6-31G** level of theory lead to a C 2 molecular conformation in the ground electronic state. The principal experimental geometric parameters are as follows: bond lengths: C3N 1.417(1), C3C av 1.403(1) A; and bond angles: CNC 123.9(5)o, and NCC 121.5o (assumed) and 116.4o.Proceeding with a systematic research into the structure of phenylphosphines [133], here we present the results of a structural study of diphenyamine (HNPH 2 ). It is important to compare the conformations and structural parameters of mono-, di-and triphenylamines and -phosphines. The analysis of phenylphosphines is presented in [3]. The structure of gaseous diphenylamine has not been studied.Quantum-chemical calculations. Geometry optimization of the diphenylamine molecule was performed by both semiempirical [439] and ab initio methods [8, 10315]. In geometry optimization, the most important parameters that determine the conformation of this molecule are piramidality of the N atom (measured by the sum of its bond angles) and torsion angles of phenyl groups relative to the C3N3C plane (Fig. 1). In view of the possibility of free rotation of phenyl groups and also the low barrier to inversion of the N atom, a number of possible conformation have been suggested for diphenylamine in the literature. Geometry optimization by semiempirical methods in different approximations (CNDO/2, INDO, MINDO/3, and MNDO) leads to a molecular conformation in which the N atom possesses a pyramidal coordination and phenyl groups have different torsion angles relative to the CNC plane. Therewith, the C 3 C 2 NC 8 and C 9 C 8 NC 2 torsion angles and differences between them depend remarkably on the method used [5]. By contrast, the AM1-optimized conformation [8] is propeller-like and has C 2 symmetry with equal torsion angles (27.7o) and a planar coordination of bonds around the N atom. Moreover, Bredas et al. [8] have been the first who performed ab initio calculations of the diphenylamine molecule with the 3-21G basis set. The results of the latter calculation gave indirect evidence to show that the AM1 method is suitable for geometry optimization of diphenylamine and its analogs. Boyle [9] have optimized the geometry of diphenylamine molecule and some of its ortho-substituted analogs by the AM1 method and found that the global minimum corresponds to an asymmetric conformation with a pyramidal N atom and that the torsion angles of the phenyl rings relative to the CNC plane depend on the configuration of bonds around the N atom (planar or pyramidal). As follows from the results of ab initio calculations with the STO-3G and 6-31G basis sets [10], the most stable conformation possesses equal 10 11...

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confidence: 99%

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Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

et al. 2005

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“…However, a different chemical composition results in different vibrational modes specific to their chemical structure. The sharp peaks of metanil yellow at 1147 cm −1 and 1433 cm −1 , due to the N = N site are most definitive to its identification and quantification [67][68][69]. The 1631 cm −1 peak in turmeric spectrum is due to the carbonyl group.…”

Section: Detection Of Metanil Yellow Contamination In Turmeric Powdermentioning

confidence: 97%

A 1064 nm Dispersive Raman Spectral Imaging System for Food Safety and Quality Evaluation

et al. 2018

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Raman spectral imaging is an effective method to analyze and evaluate the chemical composition and structure of a sample, and has many applications for food safety and quality research. This study developed a 1064 nm dispersive Raman spectral imaging system for surface and subsurface analysis of food samples. A 1064 nm laser module is used for sample excitation. A bifurcated optical fiber coupled with Raman probe is used to focus excitation laser on the sample and carry scattering signal to the spectrograph. A high throughput volume phase grating disperses the incoming Raman signal. A 512 pixels Indium-Gallium-Arsenide (InGaAs) detector receives the dispersed light signal. A motorized positioning table moves the sample in two-axis directions, accumulating hyperspectral image of the sample by the point-scan method. An interface software was developed in-house for parameterization, data acquisition, and data transfer. The system was spectrally calibrated using naphthalene and polystyrene. It has the Raman shift range of 142 to 1820 cm −1 , the spectral resolution of 12 cm −1 at full width half maximum (FWHM). The spatial resolution of the system was evaluated using a standard resolution glass test chart. It has the spatial resolution of 0.1 mm. The application of the system was demonstrated by surface and subsurface detection of metanil yellow contamination in turmeric powder. Results indicate that the 1064 nm dispersive Raman spectral imaging system is a useful tool for food safety and quality evaluation.

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Vibrational dynamics and structural investigation of 4‐benzoylpyridine

Sett

Datta

Mallick

2010

J Raman Spectroscopy

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The polarized Raman spectra in different environments along with the IR counterpart of 4-benzoylpyridine (4-BOP) were critically analyzed to assign all of its normal modes of vibration. The knowledge of the positions of different excited electronic states (EESs)was obtained from the study of electronic absorption spectra. Measurement of Raman excitation profiles (REPs)of several normal modes was carried out to get insight into structural and symmetry properties of the molecule. All the experimental observations were substantiated and corroborated theoretically by quantum chemical calculations (QCCs). The possibility of exciton splitting of the 1 L a band has been explored both from theoretical and experimental points of view.

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Raman excitation profile of diphenylamine

Cited by 28 publications

References 32 publications

Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

Molecular Structure of Diphenylamine by Gas-Phase Electron Diffraction and Quantum Chemistry

A 1064 nm Dispersive Raman Spectral Imaging System for Food Safety and Quality Evaluation

Vibrational dynamics and structural investigation of 4‐benzoylpyridine

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