79 research outputs found
Hydrated Electron Dynamics at a Five Femtosecond Time Scale
Hydrated electrons are studied by frequency resolved pump probe with 5 fs time resolution in the spectral range from 600 nm to 1000 nm. A recurrence detected in the pumpprobe signal at β40 fs is tentatively assigned to coupling to librational motions in the electron's solvent cage
Magnetization of ferrofluids with dipolar interactions - a Born--Mayer expansion
For ferrofluids that are described by a system of hard spheres interacting
via dipolar forces we evaluate the magnetization as a function of the internal
magnetic field with a Born--Mayer technique and an expansion in the dipolar
coupling strength. Two different approximations are presented for the
magnetization considering different contributions to a series expansion in
terms of the volume fraction of the particles and the dipolar coupling
strength.Comment: 19 pages, 11 figures submitted to PR
Magnetic properties of colloidal suspensions of interacting magnetic particles
We review equilibrium thermodynamic properties of systems of magnetic
particles like ferrofluids in which dipolar interactions play an important
role. The review is focussed on two subjects: ({\em i}) the magnetization with
the initial magnetic susceptibility as a special case and ({\em ii}) the phase
transition behavior. Here the condensation ("gas/liquid") transition in the
subsystem of the suspended particles is treated as well as the
isotropic/ferromagnetic transition to a state with spontaneously generated
long--range magnetic order.Comment: Review. 62 pages, 4 figure
Temperature-dependent dynamic correlations in suspensions of magnetic nanoparticles in a broad range of concentrations: A combined experimental and theoretical study
The interweave of competing individual relaxations influenced by the presence of temperature and concentration dependent correlations is an intrinsic feature of superparamagnetic nanoparticle suspensions. This unique combination gives rise to multiple applications of such suspensions in medicine, nanotechnology and microfluidics. Here, using theory and experiment, we investigate dynamic magnetic susceptibility in a broad range of temperatures and frequencies. Our approach allows, for the first time to our knowledge, to separate clearly the effects of superparamagnetic particle polydispersity and interparticle magnetic interactions on the dynamic spectra of these systems. In this way, we not only provide a theoretical model that can predict well the dynamic response of magnetic nanoparticles systems, but also deepen the understanding of the dynamic nanoparticle self-assembly, opening new perspectives in tuning and controlling the magnetic behaviour of such systems in AC fields. Β© 2016 the Owner Societies
Theoretical study of the magnetization dynamics of non-dilute ferrofluids
The paper is devoted to the theoretical investigation of the magnetodipolar
interparticle interaction effect on remagnetization dynamics in moderately
concentrated ferrofluids. We consider a homogeneous (without particle
aggregates) ferrofluid consisting of identical spherical particles and employ a
rigid dipole model, where magnetic moment of a particle is fixed with respect
to the particle itself. In particular, for the magnetization relaxation after
the external field is instantly switched off, we show that the magnetodipolar
interaction leads to the increase of the initial magnetization relaxation time.
For the complex ac-susceptibility we find that the this interaction leads to an
overall increase of the imaginary susceptibility part and shifts the peak on
its frequency dependence towards lower frequencies. Comparing results obtained
with our analytical approach (second order virial expansion) to numerical
simulation data (Langevin dynamics method), we demonstrate that the employed
virial expansion approximation gives a good qualitative description of the
ferrofluid magnetization dynamics and provides a satisfactory quantitative
agreement with numerical simulations for the dc magnetization relaxation - up
to the particle volume fraction c ~ 10% and for the ac-susceptibility - up to c
~ 5 %.Comment: 12 pages, 6 figures, submitted to PR
Π’Π΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΡ ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π² ΠΊΠ°Π½Π°Π»Π°Ρ Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ
Introduction. At present, the noise immunity of receiving multi-position signals in channels with variable parameters is improved using various signal structures (SS). In particular, in communication systems and the DVB-T2 television standard, these are quadrature amplitude modulation (QAM) signals with transformed constellation diagrams. However, in practical calculations of communication systems, the existing SS models fail to take into account the random nature of changes in the phases of the transformed signal constellation. This, in turn, leads to a discrepancy between the analytical value of error probability and its real value due to asynchronism in the radio link. The SS model proposed in this paper and the obtained analytical ratio take into account the introduced phase distortions in channels with variable parameters.Aim. Development of theoretical proposals for improving the efficiency of receiving QAM signals in radio channels with variable parameters.Materials and methods. The considered transformed SS model and the resulting analytical relation are described on the basis of communication theory and signal theory in the subject area of noise immunity research methods. This, in turn, enables analysis of the effect of phase distortions in channels with variable parameters on the error probability of receiving QAM signal elements.Results. A transformed SS model with improved energy characteristics and an analytical relation for calculating the error probability of receiving QAM signal elements are proposed. Theoretical proposals for improving the noise immunity of receiving multi-position signals in channels with variable parameters are formulated.Conclusion. The developed theoretical proposals for improving the noise immunity of multi-position quadrature signal structures in channels with variable parameters make it possible to improve their energy characteristics, taking into account phase distortions introduced by the communication channel. The presented dependence makes it possible to evaluate the relationship between the values of the probability of a pair error of receiving QAM signal elements and the limits of the change in phase shifts introduced by a communication channel with variable parameters. Future research will address the development of scientific and practical proposals for improving the noise immunity of quadrature multi-position signals, including an algorithm and block diagram for compensating phase shifts introduced in communication channels; processing of the amplitude values of the signal, which assumes the difference in the paths in terms of frequency-polarization and determines the accuracy of eliminating phase distortions.ΠΠ²Π΅Π΄Π΅Π½ΠΈΠ΅. Π Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ Π΄Π»Ρ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π² ΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠ΅ ΡΠΈΠ³Π½Π°Π»ΡΠ½ΡΠ΅ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ (Π‘Π). Π ΡΠ°ΡΡΠ½ΠΎΡΡΠΈ, Π² ΡΠΈΡΡΠ΅ΠΌΠ°Ρ
ΡΠ²ΡΠ·ΠΈ ΠΈ ΡΠ΅Π»Π΅Π²ΠΈΠ·ΠΈΠΎΠ½Π½ΠΎΠΌ ΡΡΠ°Π½Π΄Π°ΡΡΠ΅ DVB-T2 ΡΡΠΎ ΡΠΈΠ³Π½Π°Π»Ρ ΠΊΠ²Π°Π΄ΡΠ°ΡΡΡΠ½ΠΎΠΉ Π°ΠΌΠΏΠ»ΠΈΡΡΠ΄Π½ΠΎΠΉ ΠΌΠΎΠ΄ΡΠ»ΡΡΠΈΠΈ (ΠΠΠ) Ρ ΡΡΠ°Π½ΡΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½ΡΠΌΠΈ ΠΊΠΎΠ½ΡΡΠ΅Π»Π»ΡΡΠΈΠΎΠ½Π½ΡΠΌΠΈ Π΄ΠΈΠ°Π³ΡΠ°ΠΌΠΌΠ°ΠΌΠΈ. ΠΠ΄Π½Π°ΠΊΠΎ ΡΡΡΠ΅ΡΡΠ²ΡΡΡΠΈΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈ Π‘Π ΠΏΡΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°ΡΡΠ΅ΡΠ°Ρ
ΡΠΈΡΡΠ΅ΠΌ ΡΠ²ΡΠ·ΠΈ Π½Π΅ ΡΡΠΈΡΡΠ²Π°ΡΡ ΡΠ»ΡΡΠ°ΠΉΠ½ΡΠΉ Ρ
Π°ΡΠ°ΠΊΡΠ΅Ρ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΠ°Π· ΡΡΠ°Π½ΡΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠΈΠ³Π½Π°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ·Π²Π΅Π·Π΄ΠΈΡ. ΠΡΠΎ, Π² ΡΠ²ΠΎΡ ΠΎΡΠ΅ΡΠ΅Π΄Ρ, ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΡΠ°ΡΡ
ΠΎΠΆΠ΄Π΅Π½ΠΈΡ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π·Π½Π°ΡΠ΅Π½ΠΈΡ Π²Π΅ΡΠΎΡΡΠ½ΠΎΡΡΠΈ ΠΎΡΠΈΠ±ΠΊΠΈ Ρ ΡΠ΅Π°Π»ΡΠ½ΡΠΌ Π²ΡΠ»Π΅Π΄ΡΡΠ²ΠΈΠ΅ Π°ΡΠΈΠ½Ρ
ΡΠΎΠ½ΠΈΠ·ΠΌΠ° Π² ΡΠ°Π΄ΠΈΠΎΠ»ΠΈΠ½ΠΈΠΈ. ΠΡΠ΅Π΄Π»Π°Π³Π°Π΅ΠΌΠ°Ρ ΠΌΠΎΠ΄Π΅Π»Ρ Π‘Π ΠΈ ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ΅ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΡΡΠΈΡΡΠ²Π°ΡΡ Π²Π½ΠΎΡΠΈΠΌΡΠ΅ ΡΠ°Π·ΠΎΠ²ΡΠ΅ ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΡ Π² ΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ.Π¦Π΅Π»Ρ ΡΠ°Π±ΠΎΡΡ. Π Π°Π·ΡΠ°Π±ΠΎΡΠΊΠ° ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΠΉ ΠΏΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΠΠΠ Π² ΡΠ°Π΄ΠΈΠΎΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ.ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. Π Π°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°Π΅ΠΌΠ°Ρ ΡΡΠ°Π½ΡΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½Π°Ρ ΠΌΠΎΠ΄Π΅Π»Ρ Π‘Π ΠΈ ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ΅ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ ΠΎΠΏΠΈΡΠ°Π½Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠ΅ΠΎΡΠΈΠΈ ΡΠ²ΡΠ·ΠΈ, ΡΠ΅ΠΎΡΠΈΠΈ ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π² ΠΏΡΠ΅Π΄ΠΌΠ΅ΡΠ½ΠΎΠΉ ΠΎΠ±Π»Π°ΡΡΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ. ΠΡΠΎ, Π² ΡΠ²ΠΎΡ ΠΎΡΠ΅ΡΠ΅Π΄Ρ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΏΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°ΡΡ Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠ°Π·ΠΎΠ²ΡΡ
ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΠΉ Π² ΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ Π½Π° Π·Π½Π°ΡΠ΅Π½ΠΈΠ΅ Π²Π΅ΡΠΎΡΡΠ½ΠΎΡΡΠΈ ΠΎΡΠΈΠ±ΠΊΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΠΠΠ.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π° ΡΡΠ°Π½ΡΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½Π°Ρ ΠΌΠΎΠ΄Π΅Π»Ρ Π‘Π Ρ ΡΠ»ΡΡΡΠ΅Π½Π½ΡΠΌΠΈ ΡΠ½Π΅ΡΠ³Π΅ΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ°ΠΌΠΈ ΠΈ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠ΅ Π΄Π»Ρ ΡΠ°ΡΡΠ΅ΡΠ° Π²Π΅ΡΠΎΡΡΠ½ΠΎΡΡΠΈ ΠΎΡΠΈΠ±ΠΊΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΠΠΠ. Π‘ΡΠΎΡΠΌΡΠ»ΠΈΡΠΎΠ²Π°Π½Ρ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π² ΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ.ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅. Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π½ΡΠ΅ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΡ
ΠΊΠ²Π°Π΄ΡΠ°ΡΡΡΠ½ΡΡ
ΡΠΈΠ³Π½Π°Π»ΡΠ½ΡΡ
ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΉ Π² ΠΊΠ°Π½Π°Π»Π°Ρ
Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΡΠ»ΡΡΡΠΈΡΡ ΠΈΡ
ΡΠ½Π΅ΡΠ³Π΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ Ρ ΡΡΠ΅ΡΠΎΠΌ ΡΠ°Π·ΠΎΠ²ΡΡ
ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΠΉ, Π²Π½ΠΎΡΠΈΠΌΡΡ
ΠΊΠ°Π½Π°Π»ΠΎΠΌ ΡΠ²ΡΠ·ΠΈ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π½Π°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ Π΄Π°Π΅Ρ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡ ΠΎΡΠ΅Π½ΠΈΡΡ Π²Π·Π°ΠΈΠΌΠΎΡΠ²ΡΠ·Ρ ΠΌΠ΅ΠΆΠ΄Ρ Π·Π½Π°ΡΠ΅Π½ΠΈΡΠΌΠΈ Π²Π΅ΡΠΎΡΡΠ½ΠΎΡΡΠΈ ΠΏΠ°ΡΠ½ΠΎΠΉ ΠΎΡΠΈΠ±ΠΊΠΈ ΠΏΡΠΈΠ΅ΠΌΠ° ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΠΠΠ ΠΈ ΠΏΡΠ΅Π΄Π΅Π»Π°ΠΌΠΈ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΠ°Π·ΠΎΠ²ΡΡ
ΡΠ΄Π²ΠΈΠ³ΠΎΠ², Π²Π½ΠΎΡΠΈΠΌΡΡ
ΠΊΠ°Π½Π°Π»ΠΎΠΌ ΡΠ²ΡΠ·ΠΈ Ρ ΠΏΠ΅ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ. ΠΡΠΎΠΌΠ΅ ΡΠΎΠ³ΠΎ, ΡΠΊΠ°Π·Π°Π½Π½ΡΠ΅ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΡΠ΅Π΄ΠΎΠΏΡΠ΅Π΄Π΅Π»ΠΈΠ»ΠΈ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π°Π»ΡΠ½Π΅ΠΉΡΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ, Π·Π°ΠΊΠ»ΡΡΠ°ΡΡΠΈΠ΅ΡΡ Π² ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠ΅ Π½Π°ΡΡΠ½ΠΎ-ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΈΠΉ ΠΏΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΠΊΠ²Π°Π΄ΡΠ°ΡΡΡΠ½ΡΡ
ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ²: Π°Π»Π³ΠΎΡΠΈΡΠΌ ΠΈ ΡΡΡΡΠΊΡΡΡΠ½ΡΡ ΡΡ
Π΅ΠΌΡ ΠΊΠΎΠΌΠΏΠ΅Π½ΡΠ°ΡΠΈΠΈ ΡΠ°Π·ΠΎΠ²ΡΡ
ΡΠ΄Π²ΠΈΠ³ΠΎΠ², Π²Π½ΠΎΡΠΈΠΌΡΡ
Π² ΠΊΠ°Π½Π°Π»Π°Ρ
ΡΠ²ΡΠ·ΠΈ; ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΡ Π°ΠΌΠΏΠ»ΠΈΡΡΠ΄Π½ΡΡ
Π·Π½Π°ΡΠ΅Π½ΠΈΠΉ ΡΠΈΠ³Π½Π°Π»Π°, ΠΏΡΠ΅Π΄ΠΏΠΎΠ»Π°Π³Π°ΡΡΡΡ ΡΠ°Π·Π»ΠΈΡΠΈΠ΅ ΡΡΠ°ΠΊΡΠΎΠ² ΠΏΠΎ ΡΠ°ΡΡΠΎΡΠ΅-ΠΏΠΎΠ»ΡΡΠΈΠ·Π°ΡΠΈΠΈ ΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡΡΡ ΡΠΎΡΠ½ΠΎΡΡΡ ΡΡΡΡΠ°Π½Π΅Π½ΠΈΡ ΡΠ°Π·ΠΎΠ²ΡΡ
ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΠΉ
Pair Correlations in a Bidisperse Ferrofluid in an External Magnetic Field:Theory and Computer Simulations
The pair distribution function g(r) for a ferrofluid modeled by a bidisperse system of dipolar hard spheres is calculated. The influence of an external uniform magnetic field and polydispersity on g(r) and the related structure factor is studied. The calculation is performed by diagrammatic expansion methods within the thermodynamic perturbation theory in terms of the particle number density and the interparticle dipoleβdipole interaction strength. Analytical expressions are provided for the pair distribution function to within the first order in number density and the second order in dipoleβdipole interaction strength. The constructed theory is compared with the results of computer (Monte Carlo) simulations to determine the range of its validity. The scattering structure factor is determined using the Fourier transform of the pair correlation func-tion g(r) β 1. The influence of the granulometric composition and magnetic field strength on the height and position of the first peak of the structure factor that is most amenable to an experimental study is analyzed. The data obtained can serve as a basis for interpreting the experimental small[1]angle neutron scattering results and determining the regularities in the behavior of the structure factor, its dependence on the fractional com-position of a ferrofluid, interparticle correlations, and external magnetic field. Β© Pleiades Publishing, Inc., 2014
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