The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
H Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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charge Relaxation Process dominates contact charging of a particle in atmospheric condition ii the general model
Journal of Physics D, 1997Co-Authors: Tatsushi Matsuyama, H YamamotoAbstract:In this paper, the `charge-Relaxation model' proposed in our preceding paper as a scheme determining the impact charge is discussed in detail, especially for the case of an arbitrary initial charge. It is shown that the model explains well not only the `equilibrium charge' but also the `charging line' in terms of a proportional dependence of the impact charge on the initial charge. The comparison between the measured impact charge and the theoretical value shows that the measured value increases with increasing impact velocity and impact angle and has a value at saturation about 110% of that estimated by our non-empirical theory. In the case of impact charging between a conducting particle and metal plate, the charge relaxed completely. This could be explained in terms of the two-dimensional Relaxation of charge on the particle surface. Discussion and experiments on the particle-size dependence of the maximum charge showed that the maximum charge was proportional to the particle size raised to the power 1.5.
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charge Relaxation Process dominates contact charging of a particle in atmospheric conditions
Journal of Physics D, 1995Co-Authors: Tatsushi Matsuyama, H YamamotoAbstract:A new model is proposed for a mechanism dominating the charge generated on a particle due to impact or contact with metal plate. In this model, the impact/contact charging of a particle is determined as the remaining charge by the charge Relaxation Process due to gaseous discharge in atmospheric conditions; here, some difficulties of the simple condenser model are avoided. The model prediction is in good agreement with the `equilibrium charges` given as the result of impact charging experiments. Furthermore, the impact charging experiments conducted in Ar gas indicated that the impact charging characteristics changed corresponding to the breakdown limit potential of the environmental gas; this was also predicted quantitatively by the model. As a result of the proposal of this new model, hereafter in the case of treating charge generating phenomena due to impact or contact, in atmospheric conditions at least, consideration of the charge Relaxation Process due to gaseous discharge should be essential.
E A Rossler - One of the best experts on this subject based on the ideXlab platform.
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primary and secondary Relaxation Process in plastically crystalline cyanocyclohexane studied by 2h nuclear magnetic resonance i
Journal of Chemical Physics, 2013Co-Authors: B Micko, S A Lusceac, Herbert Zimmermann, E A RosslerAbstract:We study the main (α-) and secondary (β-) Relaxation in the plastically crystalline (PC) phase of cyanocyclohexane by various 2H nuclear magnetic resonance (NMR) methods (line-shape, spin-lattice Relaxation, stimulated echo, and two-dimensional spectra) above and below the glass transition temperature Tg = 134 K. Our results regarding the α-Process demonstrate that molecular motion is not governed by the symmetry of the lattice. Rather it is similar to the one reported for structural glass formers and can be modeled by a reorientation proceeding via a distribution of small and large angular jumps. A solid-echo line-shape analysis regarding the β-Process below Tg yields again very similar results when compared to those of the structural glass formers ethanol and toluene. Hence we cannot confirm an intramolecular origin for the β-Process in cyanocyclohexane. The fast β-Process in the PC phase allows for the first time a detailed 2H NMR study of the Process also at T > Tg: an additional minimum in the spin-l...
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slow secondary Relaxation Process in supercooled liquids
EPL, 1997Co-Authors: A Kudlik, C Tschirwitz, S Benkhof, T Blochowicz, E A RosslerAbstract:We report on dielectric susceptibility measurements for the glass-forming systems toluene and 1-propanol, both of which exhibit slow secondary Relaxation (Johari β-Process). We present a complete lineshape analysis for both α- and β-Process covering the real and imaginary parts. The observation of secondary Relaxation in the rigid molecule toluene shows that this Process is not of intramolecular origin. The β-Process is well resolved in the supercooled liquid and in the glass. Above Tg a strong temperature dependence of the Relaxation strength Δeβ is observed. For the activation energy Eβ of many glass-forming systems we find the relation Eβ Tg.
Tatsushi Matsuyama - One of the best experts on this subject based on the ideXlab platform.
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charge Relaxation Process dominates contact charging of a particle in atmospheric condition ii the general model
Journal of Physics D, 1997Co-Authors: Tatsushi Matsuyama, H YamamotoAbstract:In this paper, the `charge-Relaxation model' proposed in our preceding paper as a scheme determining the impact charge is discussed in detail, especially for the case of an arbitrary initial charge. It is shown that the model explains well not only the `equilibrium charge' but also the `charging line' in terms of a proportional dependence of the impact charge on the initial charge. The comparison between the measured impact charge and the theoretical value shows that the measured value increases with increasing impact velocity and impact angle and has a value at saturation about 110% of that estimated by our non-empirical theory. In the case of impact charging between a conducting particle and metal plate, the charge relaxed completely. This could be explained in terms of the two-dimensional Relaxation of charge on the particle surface. Discussion and experiments on the particle-size dependence of the maximum charge showed that the maximum charge was proportional to the particle size raised to the power 1.5.
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charge Relaxation Process dominates contact charging of a particle in atmospheric conditions
Journal of Physics D, 1995Co-Authors: Tatsushi Matsuyama, H YamamotoAbstract:A new model is proposed for a mechanism dominating the charge generated on a particle due to impact or contact with metal plate. In this model, the impact/contact charging of a particle is determined as the remaining charge by the charge Relaxation Process due to gaseous discharge in atmospheric conditions; here, some difficulties of the simple condenser model are avoided. The model prediction is in good agreement with the `equilibrium charges` given as the result of impact charging experiments. Furthermore, the impact charging experiments conducted in Ar gas indicated that the impact charging characteristics changed corresponding to the breakdown limit potential of the environmental gas; this was also predicted quantitatively by the model. As a result of the proposal of this new model, hereafter in the case of treating charge generating phenomena due to impact or contact, in atmospheric conditions at least, consideration of the charge Relaxation Process due to gaseous discharge should be essential.
A M Biradar - One of the best experts on this subject based on the ideXlab platform.
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dielectric Relaxation Process of a partially unwound helical structure in ferroelectric liquid crystals
Physical Review E, 2017Co-Authors: Amit Choudhary, Ambika Bawa, Surinder P Singh, A M BiradarAbstract:The fluctuations of unwound helical structure have been observed in deformed helix ferroelectric liquid crystal (DHFLC) and conventional FLC sample cells. The helix is partially unwound by strong anchoring on the substrates. In such sample cells, the helical decarlization lines are not observed in the texture under crossed polarized microscope. The dielectric spectroscopy is employed to observe the behavior of dielectric Relaxation Processes in these sample cells. A dielectric Relaxation Process is observed at a lower frequency than the Goldstone mode Processes in DHFLC and FLC, which we call partially unwound helical mode (p-UHM). However, the p-UHM Process is not observed in the sample cell in which the helical lines appear. The application of various amplitudes of probing ac voltages on this mode has shown the higher frequency shift, i.e., the larger the amplitude of ac voltage, the higher is the Relaxation frequency of p-UHM. At sufficient amplitude of applied probing ac voltage, the p-UHM merges with the Goldstone mode Process and is difficult to detect. However, the Goldstone mode Relaxation frequency is almost independent of the cell geometry and sample configuration. The electro-optical behavior of the p-UHM has also been confirmed by electro-optical technique. The dielectric Relaxation of UHM at a frequency lower than the Goldstone mode is interpreted as the fluctuation of partially unwound helix.
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a sub hertz frequency dielectric Relaxation Process in a ferroelectric liquid crystal material
Liquid Crystals, 2000Co-Authors: A M Biradar, D Kilian, S Wrobel, W HaaseAbstract:Dielectric studies of the first order phase transition of a ferroelectric liquid crystal material having the phase sequence chiral nematic to smectic C* have been performed using thin (2.5 mum) cells in the frequency range 0.01 Hz to 12 MHz. For planar alignment, one of the cell electrodes was covered with a polymer and rubbed. Optically well defined alignment was obtained by applying an a.c. field below the N*-SmC* transition. Charge accumulation was enhanced by depositing a thick polymer aligning layer for the alignment of the liquid crystal molecules. A sub-hertz frequency dielectric Relaxation Process is detected in smectic C*, in the chiral nematic and a few degrees into the isotropic phase, due to the charge accumulation between the polymer layer and the ferroelectric liquid crystal material. The effect of temperature and bias field dependences on the sub-hertz dielectric Relaxation Process are reported and discussed.
Atsuhiro Osuka - One of the best experts on this subject based on the ideXlab platform.
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a very rapid electronic Relaxation Process in a highly conjugated zn ii porphyrin 26 hexaphyrin zn ii porphyrin hybrid tape
Physical Chemistry Chemical Physics, 2016Co-Authors: Hirotaka Mori, Atsuhiro OsukaAbstract:The excited-state energy Relaxation Processes of a Zn(II)porphyrin–[26]hexaphyrin–Zn(II)porphyrin triply linked hybrid tape, FZn, have been investigated by femtosecond transient absorption spectroscopy (TA), using a directly meso–meso linked hybrid trimer, HZn, as a reference compound. FZn has a very small S1–S0 energy gap through the expansion of π-conjugation and the absorption band at 1897 nm corresponds to its lowest singlet excited-state as a consequence of enhanced transition dipole moment that lies parallel to the long molecular axis. In TA measurements, we observe an energy transfer Process (0.4 ps) from the Zn(II)porphyrin moiety to the [26]hexaphyrin core in HZn. In contrast to HZn, a biexponential decay with the time constants of 0.25 and 6.5 ps was observed in the decay profile of FZn. The detailed analysis of excitation wavelength, temperature and solvent dependent TA in FZn revealed that the electronic Relaxation Process (0.25 ps) from S1 to S0 is faster than the vibrational Relaxation Processes (5.9 ps) in the excited and ground states due to a very small S1–S0 energy gap through the expansion of π-conjugation. Accordingly, we demonstrate that electronic deactivation overtakes vibrational Relaxation Processes in a highly conjugated FZn.
