Low-energy electronic excitations of the ferrous ion in (Fe(H₂O)₆)(NH₄)₂(SO₄)₂by far-infrared radiation

Magnetic Circular Dichroism Spectroscopic Studies of Mononuclear Non-Heme Ferrous Model Complexes. Correlation of Excited- and Ground-State Electronic Structure with Geometry

“…The value of δ is found to be larger for 6C complexes (Table , top), generally δ > 4 cm -1 , than for 5C complexes (Table , middle), correlating with the larger nesting observed experimentally for 6C relative to 5C models (Figure ). The δ values for the [Fe(H 2 O) 6 ] 2+ complexes obtained through the VTVH MCD analysis agree with ground-state splittings determined by far-IR spectroscopies: δ = 9.9 cm -1 for [Fe(H 2 O) 6 ](SiF 6 ) 55 and δ = 6.4−6.7 cm -1 for [Fe(H 2 O) 6 ](NH 4 ) 2 (SO 4 ) 2 …”

Comparative Analysis of Experimental and Theoretical Zero-Field Splitting and Zeeman Electronic Parameters for Fe2+ Ions in FeX2·4H2O (X = F, Cl, Br, I) and [Fe(H2O)6](NH4)2(SO4)2

“…Fe 2+ , Mn 3+ , and Cr 2+ , which usually exhibit large and very large ZFS [3,7]. Similar modeling, using the package MSH/VBA [8,9] based on the microscopic spin Hamiltonian (MSH) approach, has recently been undertaken for [Fe(H 2 O) 6 ](NH 4 ) 2 (SO4) 2 (FASH) [10][11][12]. The microscopic SH (MSH) approach incorporates MSH expressions for the ZFS and Ze parameters up to fourth-order perturbation theory suitable for of 3d 4 and 3d 6 ions with spin S = 2 at orthorhombic and tetragonal symmetry sites in crystals, which exhibit an orbital singlet ground state arising from the ground 5 D multiplet [8,9].…”

“…The available data on the ground state and excited orbital states with the respective energy levels determined or adopted for Fe 2+ (S = 2) ions in FASH together with the spin-orbit coupling (SOC) constants: λ c (in crystal), λ 0 (free ion), and the orbital reduction (or covalency) factor defined as: λ c = kλ 0 are surveyed to obtain input for MSH/VBA calculations. Experimental values of the ZFS parameters and energies determined for Fe 2+ ions in FASH [10][11][12] [17] is described by the monoclinic space groups P 2 1 /c (C 5 2h ) and P 2 1 /a, respectively, each with two molecules in the unit cell. The unit cell is described by the lattice constants for FeCl 2 · 4H 2 O: a = 0.5885 nm, b = 0.7180 nm, c = 0.8514 nm, β = 111.09…”

“…More relevant data exist for FASH obtained from the Mössbauer and IR spectroscopy, e.g. [10,11,27], as summarized in [15]. For illustration the energy levels scheme suitable for the Fe 2+ ions in FASH [15] is shown in Fig.…”

Субмиллиметровые спектры ЭПР иона Fe-=SUP=-2+-=/SUP=- в кристаллах синтетического и природного бериллов

“…Это связано с тем, что для некрамерсового иона Fe 2+ спиновыми состояниями в этих случаях являются синглеты, энерге-тические интервалы между которыми превышают энер-гию квантов стандартных спектрометров. Такая ситуация реализуется, например, в кристаллах аммониевой тутто-новой соли [1] и форстерита (Mg 2 SiO 4 ) [2]. В случае аксиальной и кубической симметрии основной уровень энергии иона Fe 2+ также часто является синглетным, а вырожденные уровни от него удалены достаточно далеко, чтобы можно было наблюдать на них резонанс.…”