Determination of the hyperfine coupling constant and zero‐field splitting in the ESR spectrum of Mn²⁺ in calcite

Abstract

The hyperfine coupling constant (A in units of energy or A' in units of magnetic field) and zero-field splitting (D in units of energy or D' in units of magnetic field) in the ESR spectrum of Mn(2+) in calcite were determined. The spreading of the non-central allowed transitions |3/2, m --> |5/2, m, |1/2, m --> |3/2, m, |-3/2, m --> |-1/2, m and |-5/2, m --> |-3/2, m was analysed and the experimental transitions were attributed. Particular relevance was given to the difference between the two types of resonances, shoulder or divergence, and to their origin (M, m). The analysis explains the presence of a weak shoulder between each of the five central doublets |-1/2, m --> |1/2, m. Six independent methods for calculating the hyperfine coupling constant and five methods for calculating the zero-field splitting, based on the analysis of the allowed and forbidden transitions, were provided. The values of the hyperfine coupling constant range from -93.9 to -94.6 G and those of the zero-field splitting range from -79.5 to -80.5 G. A critical evaluation of the advantages and drawbacks of the 11 methods is included: the best value for A' is -94.30 G and that for D' is -79.95 G.

EPR OF Mn2+ IMPURITIES IN CALCITE: A DETAILED STUDY PERTINENT TO MARBLE PROVENANCE DETERMINATION*

“…Thus, large variations of the spin Hamiltonian parameters pertinent to Mn 2+ in marbles originating from different locations cannot be expected; this is consistent with the narrow ranges of spin Hamiltonian parameters found for Mn 2+ impurities in calcite; see above and Piligkos et al (2007). However, EPR spectra of Mn 2+ impurities in marble pieces originating from different locations are clearly different (see, e.g., Attanasio and Platania 2000;Polikreti and Maniatis 2000;Garriba and Micera 2006). A survey of published spectra shows that the differences are to be found in the spectral linewidths and lineshapes, as well as in the different calcite/dolomite ratio, which is a characteristic for the specific location.…”

“…(2007). However, EPR spectra of Mn 2+ impurities in marble pieces originating from different locations are clearly different (see, e.g., Attanasio and Platania 2000; Polikreti and Maniatis 2000; Garriba and Micera 2006). A survey of published spectra shows that the differences are to be found in the spectral linewidths and lineshapes, as well as in the different calcite/dolomite ratio, which is a characteristic for the specific location.…”

“…The parameter values have, in the older EPR literature, exclusively been extracted from 9-10 GHz-that is, X-band-spectra. The spectra were, in most cases, analysed in terms of the above spin Hamiltonian by means of perturbation theory; see Garriba and Micera (2006) and the references therein. The general appearance of the spectrum at X-band is, by and large, determined by the parameters D and A = A z ≈ A xy .…”

para-Aminosalicylic acid in the treatment of manganese toxicity. Complexation of Mn2+ with 4-amino-2-hydroxybenzoic acid and its N-acetylated metabolite

“…These values are compatible with an octahedral Mn 2+ species [40][41][42][43][44][45] and, in particular, with a MnO6 coordination [46][47][48][49][50]. These parameters are very similar to those of calcite and of the recently characterized Mn 2+ species formed by ethylvanillin, where Mn 2+ is surrounded by six oxygen atoms in an octahedral environment [51,52]. In contrast, A for the aquo-ion [Mn(H2O)6] 2+ (A ~ 82 × 10 4 cm 1 ) [53,54] is significantly smaller than that measured for MnL.…”

Ανάπτυξη Συνδυαστικής Μεθοδολογίας Με Επεμβατικές Και Μη-Επεμβατικές Μεθόδους Για Τη Διερεύνηση Της Προέλευσης Του Μαρμάρου Στην Αρχαιότητα

“…τθν ςυνζχεια όμωσ, με τον υπολογιςμό τθσ κατανομισ των ςπιν και τθσ πικανότθτασ μετάπτωςθσ για δείγμα ςκόνθσ με αξονικι ςυμμετρία (χ. 2.16), και με υπολογιςμό τθσ ενζργειασ με όρουσ ζωσ τρίτθσ τάξθσ ζγινε δυνατι θ ακριβισ προςομοίωςθ του ωάςματοσ, προβλζποντασ: α) τον διαχωριςμό των 6 κορυωϊν ςε 6 διπλζτεσ λόγω του μθ μθδενικοφ παράγοντα διάςχιςθσ μθδενικοφ πεδίου , β) τθν αφξθςθ του εν λόγω διαχωριςμοφ με τθν αφξθςθ του μαγνθτικοφ πεδίου λόγω του μθ μθδενικοφ και όρουσ 3 θσ τάξθσ για τθν ενζργεια, γ) τον μικρό ϊμο ανάμεςα ςτισ διπλζτεσ λόγω ενόσ ςθμείου αςυνζχειασ ςτθν ςυνάρτθςθ πικανότθτασ μετάπτωςθσ για δείγμα ςκόνθσ με αξονικι ςυμμετρία, και δ) προβλζωκθκε διαπλάτυνςθ των απαγορευμζνων κορυωϊν αντί για διαχωριςμό ςε διπλζτεσ (Beltrán-López and Castro-Tello 1980;Beltrán-López 1996;Garribba and Micera 2006) απορρίπτοντασ τθν αρχικι υπόκεςθ των Kikuchi και Matarese.…”