Possible Effects of Proton Tunnelling in Magnetically Ordered Systems

1971 ◽  
Vol 49 (20) ◽  
pp. 2599-2609
Author(s):  
D. A. Pink
Keyword(s):  
Hydrogen Bond ◽  
Low Temperature ◽  
Particle Interactions ◽  
Potential Well ◽  
Exchange Integral ◽  
Initial Assumption ◽  
Minimum Potential ◽  
Magnon Spectrum ◽  
Particle Tunnelling ◽  
Magnetically Ordered

The behavior of a magnetically ordered system in which one of the superexchange paths is through a short (~2.5 Å) hydrogen bond has been investigated with particular attention paid to the case of HCrO2. It has been assumed that the exchange integral for this path depends upon the particle (proton or deuteron) position in the bond and that the particle is tunnelling in a symmetric double-minimum potential well. The following quantities have been calculated: (i) the particle tunnelling spectrum (in particular, the infrared spectrum) for (a) general temperatures if particle–particle interactions are ignored and (b) temperatures such that few tunnelling modes are excited when these interactions are taken into account, and (ii) the low-temperature magnon spectrum, magnetization, and specific heat when particle–particle interactions are both ignored and considered. The results are compared with those that are to be expected if the initial assumption about the dependence of the exchange integral is incorrect.

Influence of the Environment on Proton Transfer in Symmetrical Hydrogen Bonds

1973 ◽  
Vol 28 (2) ◽  
pp. 236-245 ◽  
Author(s):  
E. G. Weidemann ◽  
G. Zundel
Keyword(s):  
Hydrogen Bond ◽  
Electromagnetic Field ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
The Other ◽  
Potential Well ◽  
Potential Wells ◽  
Dimensionless Parameters ◽  
Minimum Potential ◽  
Simply Connected

Symmetrical hydrogen bonds with a double minimum potential well or a largely flat potential are extremely easily polarisable, which leads to strong mutual interactions of such bonds and to interactions of the bonds with their environment. Particularly in the range of the rearrangement frequencies of the medium, the interactions depend to a marked extent on the fluctuation frequencies of the electromagnetic field and thus on the tunelling frequency of the proton in the hydrogen bond. On the other hand, the tunnelling frequency decreases due to the interactions. The correlation of the proton movements in two adjacent symmetrical hydrogen bonds and the resulting decrease of the tunnelling frequency is studied for the lowest group of levels. In addition, the decrease of the tunnelling frequency due to the effect of ion and dipole fields is calculated. In the tunnelling approximation the result depends in both cases on simple dimensionless parameters and indicates delay of the proton transfer in the bonds, but not complete hindrance. The lingering times in the potential wells are simply connected in both cases with the transition frequencies of the systems.

MAGNETIC PROPERTIES OF U1-xDyxAlyNi5-y (y=0,1) SYSTEMS

2003 ◽  
Vol 17 (27n28) ◽  
pp. 1453-1460
Author(s):  
ILEANA LUPSA
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Spin Fluctuation ◽  
Magnetic Moments ◽  
Transition Temperatures ◽  
Temperature Range ◽  
Fluctuation Model ◽  
Magnetically Ordered

The magnetic properties of U 1-x Dy x Al y Ni 5-y (y=0,1) systems were investigated in the 2(5)–600 K temperature range and for fields up to 80 kOe. The systems having x≥0.2 are magnetically ordered with low transition temperatures and magnetization mainly due to the Dy contribution. The nickel exhibits magnetic moments, very weak in the low temperature range and well-defined effective moments over transition temperatures. The nickel behavior is discussed in terms of the spin fluctuation model.

Dimerization and solvent-assisted proton dislocation in the low-barrier hydrogen bond of a Mannich base: a low-temperature NMR study

2001 ◽  
Vol 39 (S1) ◽  
pp. S81-S90 ◽  
Author(s):  
Maria Rospenk ◽  
Lucjan Sobczyk ◽  
Parwin Schah-Mohammedi ◽  
Hans-Heinrich Limbach ◽  
Nicolai S. Golubev ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Low Temperature ◽  
Mannich Base ◽  
Nmr Study

scholarly journals Field-dependent Mechanism of Anomalous Proton Conductivity and the Polarizability of Hydrogen Bonds with Tunneling Protons

1970 ◽  
Vol 25 (5) ◽  
pp. 627-634 ◽  
Author(s):  
E. G. Weidemann ◽  
G. Zundel
Keyword(s):  
Hydrogen Bond ◽  
Proton Conductivity ◽  
Excess Charge ◽  
High Proton Conductivity ◽  
Electrical Field ◽  
Preferred Direction ◽  
High Proton ◽  
Field Dependent ◽  
Minimum Potential ◽  
Dependent Mechanism

The displacement of the excess charge of the proton in acid solutions is caused by a structure migration of groupings H5O2+ or H9O4+ . The processes which take place during structure migration are discussed on the basis of results gained in IR-investigations. In an electrical field the structure migration is given a preferred direction. The hydrogen bond with the tunneling proton in H5O2+ and the grouping H3O+ in H5O2+ become polarized. Comparison of both polarizabilities demonstrates that, contrary to previous assumptions, the polarization of the hydrogen bond is the field-dependent mechanism. This conclusion is reached upon calculating the polarizability of the hydrogen bond with a symmetrical double minimum potential well. It is shown that the polarizability is extremely large, being approximately two orders of magnitude greater than that of H3O+ . Despite the large polarizability, the shift of the weights of the proton boundary structures is very small for the external fields usually applied in conductivity measurements. It is demonstrated, however, that this slight shift is large enough for the structure diffusion to obtain a preferred direction consistent with the anomalous high proton conductivity.

scholarly journals Reduced low temperature lifetimes of Bi3+ luminescence in magnetically ordered host lattices

2021 ◽  
Vol 12 ◽  
pp. 100094
Author(s):  
Hans U. Güdel ◽  
A.M. Srivastava ◽  
M.G. Brik ◽  
W.W. Beers ◽  
W.E. Cohen
Keyword(s):  
Low Temperature ◽  
Host Lattices ◽  
Magnetically Ordered
Sign in / Sign up

Export Citation Format

Share Document