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1 Jan 1990

Volume 67, Issue 1, pp. 1-595

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Signal generation mechanisms in scanning‐electron acoustic microscopy of ionic crystals

M. Urchulutegui and J. Piqueras

J. Appl. Phys. 67, 1 (1990); http://dx.doi.org/10.1063/1.346087 (4 pages) | Cited 16 times

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MgO crystals have been studied by scanning‐electron acoustic microscopy under different experimental conditions. Contrast mechanisms in imaging are discussed and compared. The experimental results obtained by earthing or nonearthing the specimen‐transducer interface suggest the existence of a signal generation mechanism that is related to the ionic nature of these kind of crystals. Electron‐acoustic microscopy appears then to be a useful tool for the characterization of ionic materials.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
62.65.+k Acoustical properties of solids
72.50.+b Acoustoelectric effects
61.72.-y Defects and impurities in crystals; microstructure

Measurements of twisted nematic cell gap by spectral and split‐beam interferometric methods

K. H. Yang and H. Takano

J. Appl. Phys. 67, 5 (1990); http://dx.doi.org/10.1063/1.345205 (5 pages) | Cited 7 times

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The transmissive Fabry–Perot interference peaks of a filled twisted nematic (TN) cell as a function of wavelength, from 400 to 600 nm and from 1100 to 2000 nm, have been used for the determination of the cell gap. Theoretical formulations have been developed to calculate the effective indices of refraction including the dispersive effect, as well as the twist geometry of the liquid‐crystal medium for both the ordinary and extraordinary waves. When the light passes through the TN medium an even number of times caused by the interfacial reflections, the equations governing the effective indices of refraction are well behaved. For an odd number of passes, the validity of these equations is restricted to a region adjacent to the Mauguin limit. The cell gaps were derived from the measured effective optical paths and the calculated indices of refraction, which include the dispersive effect with or without the twisted deformation of the liquid‐crystal medium. A general equation has also been obtained to derive the TN cell gap from the effective optical paths, which are measured by using the split‐beam interferometric method.
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61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
07.60.Ly Interferometers
42.79.-e Optical elements, devices, and systems
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Scattering of noble gas clusters with energies in the keV range

Wolfgang Knauer

J. Appl. Phys. 67, 10 (1990); http://dx.doi.org/10.1063/1.345289 (8 pages) | Cited 4 times

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Noble gas clusters with an average size of several thousand atoms and with energies in the keV range were directed at metal surfaces under small angles of incidence. The scatter products were examined with respect to size, energy, and recoil angle. All observations fit an impact model in which the tangential momentum is preserved during impact, while the normal kinetic energy is converted to cluster heat. The associated temperature rise results in the evaporation of cluster atoms. Small clusters evaporate completely; large clusters are reduced in size. The evaporated atoms continue in a forward direction (together with the residual cluster fragments) and form a well‐collimated and energetic atom beam.
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29.27.-a Beams in particle accelerators
79.20.-m Impact phenomena (including electron spectra and sputtering)
44.30.+v Heat flow in porous media

Relativistic recoil and the railgun

J. E. Allen and T. V. Jones

J. Appl. Phys. 67, 18 (1990); http://dx.doi.org/10.1063/1.346056 (4 pages) | Cited 4 times

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It is shown that the concept of electromagnetic momentum can be used to calculate the force acting on the projectile in a railgun, thereby refuting some recent papers on the subject.
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03.50.De Classical electromagnetism, Maxwell equations
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
41.90.+e Other topics in electromagnetism; electron and ion optics (restricted to new topics in section 41)

Evanescent wave excitation of the surface polariton

Guifang Li and S. R. Seshadri

J. Appl. Phys. 67, 22 (1990); http://dx.doi.org/10.1063/1.345285 (10 pages) | Cited 4 times

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The characteristics of the surface polariton existing on the surface of a free electron metal in the proximity of a higher permittivity prism dielectric are investigated including the effects of the finite length of the prism dielectric and the slow spatial variation of the amplitude of the surface polariton. The radiative decay characteristics of the surface polariton and the characteristics of the antiresonance in the angular response of the reflectivity of light incident on the metal surface via the air gap from the prism dielectric are treated, and the effect of a small loss in the metal on these characteristics is also presented.
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03.50.De Classical electromagnetism, Maxwell equations
41.20.Jb Electromagnetic wave propagation; radiowave propagation
42.79.Gn Optical waveguides and couplers
42.79.Bh Lenses, prisms and mirrors
42.79.Fm Reflectors, beam splitters, and deflectors

Transmission of an electrostatic potential through an arbitrary stack of dielectric plates: Theoretical and experimental study

Gerard Tremblay, Paul Meyrueix, and Jean Claude Peuzin

J. Appl. Phys. 67, 32 (1990); http://dx.doi.org/10.1063/1.345257 (4 pages)

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We consider in this paper an arbitrary stack of dielectric plates with given voltage distributions at both lower and upper free surfaces of the stack. We address the problem of finding the potential distribution at any interface within the stack. This problem is of fundamental importance regarding a recently proposed electro‐optical technique for testing printed‐circuit boards. We have developed a simple and powerful matrix formalism relying on Fourier transformations of voltage distributions. The theory is verified against a particular kind of stack that is of practical importance in the already mentioned application. This stack is composed of three successive layers: an isotropic dielectric, a one‐dimensional elastomeric conductor, and an electro‐optic crystal (Bi4Ge3O12). The last surface of the stack is grounded using a conductive (and transparent) electrode, whereas a given potential distribution is applied to the first surface. The potential distribution on the ungrounded face of the electro‐optic plate (that side in contact with the elastomer) is measured using an optical reflective polarimetric technique. Our results demonstrate good agreement between theory and experiment.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
78.20.Jq Electro-optical effects
02.60.Gf Algorithms for functional approximation

Charge retention of twisted nematic liquid‐crystal displays

K. H. Yang

J. Appl. Phys. 67, 36 (1990); http://dx.doi.org/10.1063/1.345263 (4 pages) | Cited 6 times

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A simulated thin‐film transistor (TFT) circuit has been built to drive the twisted nematic (TN) cell for the measurements of charge retention and the transmission versus peak voltage applied to the drain electrode of the simulated TFT using the gate pulse width as a parameter. The established rule that the transmission of the TN cell depends only on the rms voltage applied to the cell has been confirmed by calculating the rms voltage of the charge retention curves in correlation with the measured transmissions. The deviation of the decaying charge retention curves from the exponential behavior has been observed and can be qualitatively explained by a combination of the dielectric and transport properties of nematic liquid‐crystal medium.
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61.30.-v Liquid crystals
85.60.Pg Display systems
07.50.Ek Circuits and circuit components

Theoretical intensity‐dependent response of nonlinear periodic structures

Paul A. Gohman, Gust Bambakidis, and Robert J. Spry

J. Appl. Phys. 67, 40 (1990); http://dx.doi.org/10.1063/1.345271 (5 pages) | Cited 6 times

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We have modeled the response of a nonlinear periodic structure by means of the Abelés 2×2 matrix method. Our structure differs from the usual rejection‐band filter designs, in that we have chosen the filter elements to be index matched in the absence of radiation, providing a rejection band that both grows and shifts as a function of incident intensity. The intensity output function of the model not only directly demonstrates optical bistability, but also limiting, switching, self‐pulsing, and chaos.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects

Optically pumped titanium vapor laser at 551.4 nm

K. Hirata, S. Yoshino, and H. Ninomiya

J. Appl. Phys. 67, 45 (1990); http://dx.doi.org/10.1063/1.345226 (4 pages) | Cited 3 times

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The output characteristics of an optically pumped titanium vapor laser on various buffer gas species and pressures have been measured, and the role of buffer gas on the laser output is accordingly discussed. He, Ne, Ar, and Kr are used as buffer gases. The optimum condition for the maximum output energy is 4 Torr of He with 10 μs delay time.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Acousto‐optic control and modulation of optical coherence by electronically synthesized holographic gratings

Jari Turunen, Eero Tervonen, and Ari T. Friberg

J. Appl. Phys. 67, 49 (1990); http://dx.doi.org/10.1063/1.345232 (11 pages) | Cited 23 times

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We introduce a new technique to modify the coherence properties and the far‐field intensity distributions of optical fields. Use is made of a combination of Bragg diffraction and Raman–Nath diffraction in an acousto‐optic deflector. The high‐frequency Bragg grating in the deflector is phase modulated by a synthetic low‐frequency Raman–Nath regime grating that has a structure of an optimized phase‐only computer‐generated hologram. We demonstrate, e.g., electronic control of the state of spatial coherence of light, Gaussian to flat‐top conversion, and the generation of arrays of equally intense but mutually incoherent light spots.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.40.-i Holography
42.25.Bs Wave propagation, transmission and absorption

On the normal acceleration sensitivity of contoured quartz resonators rigidly supported along rectangular edges

H. F. Tiersten and D. V. Shick

J. Appl. Phys. 67, 60 (1990); http://dx.doi.org/10.1063/1.345206 (8 pages) | Cited 9 times

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An analysis of the normal acceleration sensitivity of contoured AT‐ and SC‐cut quartz crystal resonators rigidly supported along rectangular edges is performed. The variational principle with all natural conditions for anisotropic static flexure is used in the calculation of the flexural biasing state. However, in this work the biasing shearing stresses with quadratic variation across the thickness of the plate are obtained a posteriori from the flexural solution in the conventional manner. The accompanying quadratically varying biasing shearing strains, which are very important in this work, are obtained from the constitutive equations along with all other quadratically varying strains resulting from the anisotropy. The calculated biasing deformation fields are employed in an existing perturbation equation along with the mode shapes of the contoured resonators to calculate the normal acceleration sensitivities. It is shown that the normal acceleration sensitivity vanishes for many cases and is less than a few parts in 1013 for all cases considered.
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43.38.Fx Piezoelectric and ferroelectric transducers
77.65.-j Piezoelectricity and electromechanical effects
62.20.D- Elasticity

Optical heterodyne investigation of the ultrasonic properties of aqueous biomolecules, dimethyl sulfoxide, and 1,4‐butanediol

Rob Bonney and Christopher C. Davis

J. Appl. Phys. 67, 68 (1990); http://dx.doi.org/10.1063/1.345207 (8 pages)

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An optical heterodyne technique has been used to make new measurements of the ultrasonic properties of aqueous solutions of biomolecules, dimethyl sulfoxide, and 1,4‐butanediol. A LiNbO3 transducer provided acoustic excitation from 0.2 to 1.5 GHz. Acoustic velocity and attenuation were measured using angularly resolved detection of Bragg‐scattered light from the liquid sample. A thermodynamic theory based on the heat of mixing was used to explain the concentration dependence of the liquid mixture properties. This paper contributes new data at high frequencies, a calculation of measurement sensitivity for this technique, and a complete treatment of a little known thermodynamic theory that describes these results.
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43.58.+z Acoustical measurements and instrumentation
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
07.60.Ly Interferometers
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products

Nonlinearity parameter, nonlinearity constant, and frequency dependence of ultrasonic attenuation in GaAs

D. N. Joharapurkar and M. A. Breazeale

J. Appl. Phys. 67, 76 (1990); http://dx.doi.org/10.1063/1.345208 (5 pages) | Cited 3 times

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Mason’s nonlinearity constants D [W. P. Mason, in Physical Acoustics, edited by W. P. Mason (Academic, New York, 1965), Vol. IIIB, Chap. VI] in GaAs at 298 K have been estimated from second‐ and third‐order elastic constants along the [100], [110], and [111] directions for longitudinal and shear waves. These values are further used to estimate the frequency dependence of the ultrasonic attenuation in the range 40–640 MHz and are found to be in good agreement when compared with experimental values available in the literature. Previously, it was established that phonon‐phonon interactions produce a drag on moving dislocations in a solid. In the present work, the drag coefficients for edge and screw dislocations along the [100] and [110] directions in single‐crystal GaAs have been estimated from the evaluated nonlinearity constant D values at 298 K. We have also estimated the values of Breazeale’s nonlinearity parameters β [M. A. Breazeale and J. Philip, in Physical Acoustics, edited by W. P. Mason and R. N. Thurston (Academic, New York, 1984), Vol. XVII, Chap. I] along the [100], [110], and [111] directions and found them to be consistent for the three principal orientations, compared with the results for other samples. It is pertinent to note that the mode Grüneisen number γ ji involved in the estimation of Mason’s nonlinearity constant D is deceptively similar to Breazeale’s nonlinearity parameter β. The nonlinearity constant D is evaluated from knowledge of the Grüneisen number γ ji for various modes and directions, whereas Breazeale’s nonlinearity parameter β is the negative ratio of coefficients of nonlinear term to the linear term of the (dissipationless) nonlinear wave equation for pure mode directions. Both D and β, in general, are temperature dependent.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.35.Gk Phonons in crystal lattices, quantum acoustics
63.20.kg Phonon-phonon interactions
61.72.Lk Linear defects: dislocations, disclinations

On optimal heating and cooling strategies for melting and freezing

J. M. Gordon, I. Rubinstein, and Y. Zarmi

J. Appl. Phys. 67, 81 (1990); http://dx.doi.org/10.1063/1.345209 (4 pages) | Cited 8 times

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For a one‐dimensional liquid or solid slab that undergoes freezing or melting, we solve for the cooling or heating strategy that, subject to certain constraints and approximations, minimizes entropy production and hence maximizes potentially available work. The key constraint is that the freezing or melting process must be completed in a given fixed time. This constraint can correspond, for example, to a fixed production rate in an industrial process. The validity of this optimal strategy and its practical significance are discussed.
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64.70.D- Solid-liquid transitions
44.10.+i Heat conduction
05.70.Ln Nonequilibrium and irreversible thermodynamics

Negative hydrogen ion densities and drift velocities in a multicusp ion source

P. J. Eenshuistra, M. Gochitashvilli, R. Becker, A. W. Kleyn, and H. J. Hopman

J. Appl. Phys. 67, 85 (1990); http://dx.doi.org/10.1063/1.345210 (12 pages) | Cited 26 times

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We have determined densities of negative hydrogen ions in a discharge by a laser detachment technique. We measured the electron density, the electron temperature, and the positive ion density using a Langmuir probe. We also performed extraction measurements. Combination of H− density measurements and extraction measurements yields information about the H− drift velocity. It was found that the velocity scaled with the square root of the electron temperature. All measurements were done as a function of discharge voltage, discharge current, and gas pressure. The densities are compatible with a semiquantitative model in which H− is produced by dissociative attachment of plasma electrons to vibrationally excited molecules and destroyed by wall collisions at very low pressure and collisions with H atoms, positive ions and/or hot thermal electrons at higher pressure.
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52.20.-j Elementary processes in plasmas
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
33.80.Eh Autoionization, photoionization, and photodetachment

Optical emission spectroscopy of rf discharge in SF6

S. B. Radovanov, B. Tomčik, Z. Lj. Petrović, and B. M. Jelenković

J. Appl. Phys. 67, 97 (1990); http://dx.doi.org/10.1063/1.345211 (11 pages) | Cited 20 times

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In this paper we present experimental results obtained for a rf discharge in SF6 and for SF6 with Ar and/or N2. The data for power dependence of some emission lines usually used in actinometry are acquired and their applicability and excitation kinetics discussed. We also present the spatial (time averaged) variations of some emission lines. From such data the spatial dependence of the high‐energy tail of the electron energy distribution function may be obtained.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Dg Plasma kinetic equations
52.80.Pi High-frequency and RF discharges

Theoretical and experimental characterization of positive‐column plasmas in oxygen glow discharge

Yukimi Ichikawa, Richard L. C. Wu, and Teruo Kaneda

J. Appl. Phys. 67, 108 (1990); http://dx.doi.org/10.1063/1.345288 (7 pages) | Cited 11 times

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Combined theoretical and experimental studies have been accomplished in order to elucidate the features of positive columns in oxygen glow discharges. The Langmuir probe technique was utilized to measure the plasma parameters such as electron temperature and electric field. A tandem mass spectrometer was used to measure relative concentrations of charged particles. These experimental results were found to be in good agreement with the present theoretical calculations based on a slightly ionized stationary plasma model.
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52.80.Hc Glow; corona
52.65.-y Plasma simulation
52.25.Dg Plasma kinetic equations

Electrodeless high‐pressure microwave discharges

Stephan Offermanns

J. Appl. Phys. 67, 115 (1990); http://dx.doi.org/10.1063/1.346088 (9 pages) | Cited 14 times

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A one‐dimensional numerical model has been developed to describe a cylindrical high‐pressure mercury plasma sustained by microwave energy within a cavity applicator by solving Maxwell’s equations together with the energy balance equation. The mercury line radiation has been taken into account for the energy balance by solving the radiation transfer equation for all significant wavelengths. An experimental microwave circuit for the frequency range of 2–4 GHz (S band) has been designed to guarantee stable discharge operation. Coupling efficiencies >99% into the microwave cavity can always be achieved with proper adjustments. Variation of discharge parameters leads to different types of temperature distributions including profiles with a local minimum in the axis. The temperature distributions predicted by the model are in good agreement with results from spectroscopic experiments.
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52.50.Gj Plasma heating by particle beams
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.40.-w Plasma interactions (nonlaser)
51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)

The use of high‐order TM0m0 modes of a resonant cavity for magnetized plasma density measurements

P. J. Paris, M. L. Sawley, M. Q. Tran, and K. Voser

J. Appl. Phys. 67, 124 (1990); http://dx.doi.org/10.1063/1.345290 (6 pages) | Cited 2 times

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A study of the application of high‐order TM0m0 modes of a cylindrical cavity to the measurement of the density of a magnetized plasma column is presented. It is shown theoretically that judiciously chosen high‐order modes have the potential advantages of both a wide operational range of densities, and a wide range for which a simple perturbation theory is valid. Furthermore, an experiment is described which shows that the TM060 mode can be excited with a sufficiently high Q value to allow accurate determination of the resonant frequencies, and hence plasma density. Favorable comparison between densities in the range 1010–1012 cm−3 measured by means of the resonant cavity technique and microwave interferometry is presented.
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52.70.-m Plasma diagnostic techniques and instrumentation

Experimental characteristics of rf parallel‐plate discharges: Influence of attaching gases

P. Bletzinger

J. Appl. Phys. 67, 130 (1990); http://dx.doi.org/10.1063/1.345291 (9 pages) | Cited 22 times

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Electrical characteristics of parallel‐plate rf discharges were measured with the goal of obtaining quantitative information of the properties of the discharges, in particular the electrode sheaths. Measurements of the impedance characteristics at variable electrode spacing suggest a transition of the power deposition process from volume to electrode dominated at about 1 Torr in argon. By changing the secondary electrode emission coefficient of the electrodes, it could be shown that the power into electrons emitted from the electrodes is small compared to the total power input. Adding the attachers CF4, C2F6, and SF6 caused a large increase of the discharge impedance in the high‐pressure (volume power deposition) regime and shifted the transition to the electrode‐dominated power deposition regime to lower pressures. The impedance behavior versus pressure was modeled with a simple equivalent electrical circuit from which the characteristics of the electrode sheaths and their influence on the electrical characteristics could be derived. The time‐averaged sheath thickness was measured optically and compared with the results using the equivalent circuit. The sheath thickness, decreasing on addition of the attaching gases CF4 and SF6, is quite different for these two added gases, which have about the same ionization, but very different attachment cross sections. In contrast, the impedance with added CF4 is only slightly less than with SF6, indicating an average electron energy of at least 5 eV where the attachment rates of the two gases become similar. Using variable electrode spacing, the peak electric field was measured both in the electrode sheaths and in the discharge volume. For argon with 23% added SF6, at 1 Torr pressure, the field in the sheath reached 569 and 27 V/cm in the volume; at 0.15 Torr the fields were 300 V/cm in the sheath and below the measurement accuracy in the volume.
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51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)
52.80.Pi High-frequency and RF discharges

Spatial distribution of a‐Si:H film‐producing radicals in silane rf glow discharges

D. A. Doughty and A. Gallagher

J. Appl. Phys. 67, 139 (1990); http://dx.doi.org/10.1063/1.345292 (7 pages) | Cited 30 times

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Film growth on glass fibers (40 μm diameter) is used to probe the distribution of SiH4 decomposition products that produce a‐Si:H films in silane rf glow discharges. The film thickness on fibers spanning the electrodes is measured versus position to map the spatial variation of the film‐precursor (radical) density. The optical emission from the discharge, which is shown to be essentially equivalent to the distributed source of SiH4 decomposition products, is compared to the density maps. This comparison shows that the SiH3 radical dominates deposition, that this SiH3 is produced in the optically bright regions of the discharge, and that H atoms react rapidly with SiH4 before diffusing significant distances in the discharge. The perturbative nature of the probes on the discharge environment is also addressed.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Nitrogen ion dynamics in low‐pressure nitrogen plasma and plasma sheath

D. E. Gerassimou, S. Cavadias, D. Mataras, and D. E. Rapakoulias

J. Appl. Phys. 67, 146 (1990); http://dx.doi.org/10.1063/1.345293 (8 pages) | Cited 6 times

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Laser‐induced fluorescence (LIF) excitation and time‐resolved LIF spectroscopy have been used to explore the interaction of a nitrogen plasma with a metal surface. The rotational temperature, the concentration of N+2, and the lifetime of N+2(B2Σ+u)υ=0 were measured as a function of distance from the metal surface. It was observed that the lifetime of the excited ion decreases sharply in the plasma sheath which is created in front of the metal surface. The concentration of N+2(X 2Σ+g), which was measured simultaneously with the lifetime of excited N+2, indicates a quasilinear decrease from the cathode to the grounded surface. Trot undergoes a gradual reduction from the bulk plasma up to the surface where its value is a good approximation of the surface temperature. An interpretation of these phenomena including a numerical simulation of the lifetime decrease is proposed here. The calculated values are in good agreement with experimental results. The dependence of lifetime decrease on the sheath potential as well as on other important parameters (cross section, profile of the electric field) is further discussed.
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52.80.Hc Glow; corona
52.40.Hf Plasma-material interactions; boundary layer effects
32.50.+d Fluorescence, phosphorescence (including quenching)

A model of dc glow discharges with abnormal cathode fall

Karl H. Schoenbach, Hao Chen, and G. Schaefer

J. Appl. Phys. 67, 154 (1990); http://dx.doi.org/10.1063/1.345294 (9 pages) | Cited 21 times

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A model for an abnormal glow discharge, including a self‐consistent analysis of the cathode fall, was developed. It combines microscopic particle simulation by means of Monte Carlo methods with a fluid model of the gas discharge. The model allows calculations of the steady‐state electrical field distribution, the charged‐particle densities, and the current densities along the axis of the discharge. The model was used to simulate a glow discharge in 80% He and 20% SF6 at a pressure of 8 Torr with a current density of 1 A/cm2. The computed discharge voltage agrees well with measured values. The computer code can easily be modified to describe the charged‐particle densities and energies not only in the cathode fall region, but in any plasma boundary layer.
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52.80.Hc Glow; corona
52.65.-y Plasma simulation
52.40.Hf Plasma-material interactions; boundary layer effects

Isotopic exchange in hard amorphous carbonized layers

D. Boutard, W. Möller, and B. M. U. Scherzer

J. Appl. Phys. 67, 163 (1990); http://dx.doi.org/10.1063/1.345296 (6 pages) | Cited 8 times

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Hard amorphous films of a‐C:H and a‐C:D were deposited by a rf glow discharge in either CH4 or CD4 . By ion bombardment with protons and deuterons, the H/D exchange process was studied as function of the bombardment fluence by means of depth profile measurements. The local hydrogen and deuterium contents are not adding up to a constant ‘‘saturation’’ value: the local mixing model is not valid. Instead of that an initial depletion appears, which depends on the incident energy of the ions. At higher fluences, the total (H+D):C ratio tends to increase again, due to an increasing influence of the deposition process. This demonstrates a structural difference between a‐C:H films and hydrogen‐saturated layers of implanted carbon.
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61.80.Jh Ion radiation effects
66.30.J- Diffusion of impurities
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Dynamical response of cholesteric liquid crystals under dilative stresses

N. Scaramuzza, V. Carbone, J. P. Marcerou, and R. Bartolino

J. Appl. Phys. 67, 169 (1990); http://dx.doi.org/10.1063/1.345276 (4 pages) | Cited 3 times

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We present a theoretical treatment and experimental data for the dynamical behavior of a cholesteric liquid crystal submitted to uniaxial dilative strains applied along the helical axis. The results show the importance of the permeative contribution in the transient regime before a new equilibrium state is found where the apparent pitch is varied.
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64.70.M- Transitions in liquid crystals
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