Magnetic Dipole Origins of the 3A2g→3T2g Transition in Ni(II) Doped MgO

2012 ◽  
Vol 65 (9) ◽  
pp. 1298 ◽  
Author(s):  
Mark J. Riley ◽  
Jeremy Hall ◽  
Elmars R. Krausz
Keyword(s):  
Magnetic Dipole ◽  
Near Infrared ◽  
Magnetic Circular Dichroism ◽  
Linear Dichroism ◽  
Tetragonal Symmetry ◽  
Double Quantum ◽  
Spin Orbit ◽  
Paramagnetic Resonance ◽  
Magnetic Linear Dichroism ◽  
Jahn Teller

Magnetic circular dichroism and magnetic linear dichroism spectroscopy have been used to study the near infrared 3A2g → 3T2g transition of Ni(ii) doped MgO. Two sharp electronic origins are observed and it is show that their polarisation behaviour follows that expected from calculations in detail for magnetic dipole allowed transitions in octahedral symmetry. Not all transitions to the spin-orbit components of the 3T2g state are observed. We put forward an explanation for why some components are missing, even though they are expected to be of comparable intensity, in terms of the different coupling to the Jahn–Teller active tetragonal distortion in the excited state. The two lower energy spin-orbit split components are nearly independent of this distortion, while the two higher energy components are strongly dependent. We also examine the double quantum transition in the electron paramagnetic resonance spectrum and estimate the magnitude of the random strain of tetragonal symmetry in the MgO lattice.

scholarly journals Paramagnetic resonance in the copper Tutton salts

1949 ◽  
Vol 198 (1054) ◽  
pp. 406-428 ◽  
Keyword(s):  
Magnetic Dipole ◽  
Dipole Interaction ◽  
Tetragonal Symmetry ◽  
Magnetic Dipole Interaction ◽  
Crystalline Electric Field ◽  
Paramagnetic Resonance ◽  
Tutton Salts ◽  
Line Shapes ◽  
The Mean ◽  
Double Sulphates

Part I . Seven of the double sulphates and selenates (‘Tutton salts’) of copper have been examined by the method of paramagnetic resonance. The deviation of the effective gyromagnetic ratio from the free-spin value of 2 is shown to be generally consistent with the theory of Polder (1942), who assumes a crystalline electric field of tetragonal symmetry to act on each ion. In some salts an appreciable departure from tetragonal symmetry is observed. Part II . The variation of the width of the absorption lines with the direction of the applied magnetic field is studied and compared with that calculated from magnetic dipole interaction. The line shapes show that exchange interaction is present in varying degree, though much less powerful than in copper sulphate. The ‘mean square moment’ of the lines can be explained by the magnetic dipole interaction, together with a contribution from a hyperfine structure which is not resolved except in a highly diluted salt.

scholarly journals Effects of Symmetry on Circular and Linear Magnetic Dichroism in Angle-Resolved Photoemission Spectra of Gd/Y(0001) and Fe-Ni/Cu(001)

1997 ◽  
Vol 475 ◽  
Author(s):  
K.W. Goodman ◽  
J.G. Tobin ◽  
F.O. Schumann ◽  
R.F. Willis ◽  
J.W. Gammon ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
Linear Dichroism ◽  
Experimental Results ◽  
Alloy Films ◽  
Magnetic Dichroism ◽  
Ni Alloy ◽  
Magnetic Linear Dichroism ◽  
Circular Dichroïsm

ABSTRACTWe have observed circular and linear magnetic dichroisms in angle-resolved photoemission spectra of 50-monolayer Gd films grown on Y(0001) and 6-monolayer Fe-Ni alloy films grown on Cu(001). The 4/level of Gd and the Fe 3p level of the Fe-Ni alloy were measured. A different geometry was used for the magnetic circular dichroism than was used to measure the magnetic linear dichroism. The geometries were chosen so that the magnetic circular dichroism is predicted to be closely related to the magnetic linear dichroism for four-fold symmetric Fe-Ni/Cu(001) but not for three-fold symmetric Gd-Y(0001). Experimental results are presented.

scholarly journals Characterization of the partially reduced cyanide-inhibited derivative of cytochrome c oxidase by optical, electron-paramagnetic-resonance and magnetic-circular-dichroism spectroscopy

1981 ◽  
Vol 193 (3) ◽  
pp. 699-708 ◽  
Author(s):  
M K Johnson ◽  
D G Eglinton ◽  
P E Gooding ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Circular Dichroism ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Near Infrared ◽  
Magnetic Circular Dichroism ◽  
Circular Dichroism Spectroscopy ◽  
Paramagnetic Resonance ◽  
Magnetic Circular Dichroism Spectroscopy ◽  
Circular Dichroïsm ◽  
Reduced State

Optical. e.p.r. and near-infrared low-temperature m.c.d. (magnetic-circular-dichroism) spectroscopy were used to characterize the partially reduced cyanide-inhibited derivative of cytochrome c oxidase produced by anaerobic reductive titration with dithionite. The reductions of cytochrome a3+ and Cu2+a were followed by observation of the e.p.r. signals at g = 3.03, 2.21 and 1.5 and at g = 2.18, 2.03 and 1.99. As reduction proceeds new e.p.r. signals (g = 3.58 and 1.56) appear that quantify to give one haem per enzyme unit when a small excess of dithionite has been titrated in. The e.p.r. signal of the Cu2+a titrates in parallel with the disappearance of the band and 820nm in the optical absorption spectrum. The near-infrared m.c.d. spectrum shows the presence of the low-spin ferric haem, a3+, in the oxidized state of the enzyme, as a well-resolved positive peak at 1650nm. As reduction proceeds this band is replaced by one at 1550nm due to haem a3+(3)–CN in the partially reduced state. Hence as haem a3+(3)–CN becomes e.p.r.-detectable it also shows a near-infrared m.c.d. spectrum characteristic of a low-spin ferric haem. It is concluded that the partially reduced state of cyanide-inhibited cytochrome c oxidase contains a2+ . Cu+a . a3+(3)–CN . Cu+a3.

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