Using the combined approach of 35Cl NQR, 14N NQR and DFT calculations to study the 14N NQR spectrum of diazepam

K. Bronisz, M. Ostafin, O. Kh Poleshchuk, J. Mielcarek, B. Nogaj

    Research output: Contribution to journalArticle

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    Abstract

    The electronic structure of diazepam was analyzed by pulsed 14N nuclear quadrupole resonance (NQR) spectroscopy and density functional theory (DFT) calculations using the hybrid method B3PW91 with the 6-31G(d,p) basis set. Before searching for 14N NQR spectra, a 35Cl NQR line in diazepam was recorded to evaluate the degree of disorder in the crystal lattice and thus the chances to find much weaker NQR spectra of nitrogen-14 in this substance. In order to speed up the detection of weak NQR spectra, the spin-locked spin-echo multipulse sequence had to be applied. Despite the expected chemical inequivalence of the two nitrogen atoms in the diazepam molecule, only two resonance lines ν + and ν - were then found for this compound at 77 K. Possible reasons for this anomaly are discussed. From the experimental frequencies, the quadrupole coupling constant, the asymmetry parameter and the principal components of the electric field gradient tensor were determined. Those parameters were compared with the results of theoretical DFT calculations showing a reasonable accuracy of the DFT model used.

    Original languageEnglish
    Pages (from-to)183-191
    Number of pages9
    JournalApplied Magnetic Resonance
    Volume34
    Issue number1-2
    DOIs
    Publication statusPublished - Jul 2008

    Fingerprint

    nuclear quadrupole resonance
    density functional theory
    resonance lines
    crystal lattices
    nitrogen atoms
    echoes
    quadrupoles
    asymmetry
    disorders
    tensors
    anomalies
    electronic structure
    nitrogen
    gradients
    electric fields
    spectroscopy
    molecules

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics

    Cite this

    Using the combined approach of 35Cl NQR, 14N NQR and DFT calculations to study the 14N NQR spectrum of diazepam. / Bronisz, K.; Ostafin, M.; Poleshchuk, O. Kh; Mielcarek, J.; Nogaj, B.

    In: Applied Magnetic Resonance, Vol. 34, No. 1-2, 07.2008, p. 183-191.

    Research output: Contribution to journalArticle

    Bronisz, K. ; Ostafin, M. ; Poleshchuk, O. Kh ; Mielcarek, J. ; Nogaj, B. / Using the combined approach of 35Cl NQR, 14N NQR and DFT calculations to study the 14N NQR spectrum of diazepam. In: Applied Magnetic Resonance. 2008 ; Vol. 34, No. 1-2. pp. 183-191.
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