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13 Sep 2010

Volume 97, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 97, 113701 (2010); http://dx.doi.org/10.1063/1.3487998 (3 pages)

Sarah E. Baker, Michael D. Pocha, Allan S. P. Chang, Donald J. Sirbuly, Stefano Cabrini, Scott D. Dhuey, Tiziana C. Bond, and Sonia E. Létant
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Strongly coupled single quantum dot in a photonic crystal waveguide cavity

F. S. F. Brossard, X. L. Xu, D. A. Williams, M. Hadjipanayi, M. Hugues, M. Hopkinson, X. Wang, and R. A. Taylor

Appl. Phys. Lett. 97, 111101 (2010); http://dx.doi.org/10.1063/1.3487937 (3 pages) | Cited 2 times

Online Publication Date: 13 September 2010

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Cavities embedded in photonic crystal waveguides offer a promising route toward large scale integration of coupled resonators for quantum electrodynamics applications. In this letter, we demonstrate a strongly coupled system formed by a single quantum dot and such a photonic crystal cavity. The resonance originating from the cavity is clearly identified from the photoluminescence mapping of the out-of-plane scattered signal along the photonic crystal waveguide. The quantum dot exciton is tuned toward the cavity mode by temperature control. A vacuum Rabi splitting of ∼ 140 μeV is observed at resonance.
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42.79.Gn Optical waveguides and couplers
42.70.Qs Photonic bandgap materials
68.65.Hb Quantum dots (patterned in quantum wells)

Many-body and nonequilibrium effects on relaxation oscillations in a quantum-dot microcavity laser

Benjamin Lingnau, Kathy Lüdge, Eckehard Schöll, and Weng W. Chow

Appl. Phys. Lett. 97, 111102 (2010); http://dx.doi.org/10.1063/1.3488004 (3 pages) | Cited 2 times

Online Publication Date: 13 September 2010

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We investigate many-body and nonequilibrium effects on the dynamical behavior of a quantum-dot laser diode. Simulations, based on the Maxwell-semiconductor-Bloch equations, show strong dependence of the turn-on delay on initial cavity detuning, because of a dynamical shift in the quantum-dot distribution caused by band gap renormalization. Gain switch behavior is found to be insensitive to inhomogeneous broadening, because the balancing between many-body and free-carrier effects inhibits a cavity resonance walk-off. Both the relaxation oscillation damping and frequency are found to increase with decreasing inhomogeneous broadening widths. However, in contrast to bulk and quantum-well lasers, oscillation damping increases less than the frequency.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Photoluminescence quenching dynamics in cadmium telluride and gallium arsenide induced by ultrashort terahertz pulse

Jingle Liu, Gurpreet Kaur, and X.-C. Zhang

Appl. Phys. Lett. 97, 111103 (2010); http://dx.doi.org/10.1063/1.3489102 (3 pages) | Cited 3 times

Online Publication Date: 13 September 2010

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The quenching dynamics of femtosecond-optical-pulse-induced photoluminescence in semiconductors under the influence of single-cycle terahertz pulses has been experimentally investigated. When electron kinetic energy gained from the terahertz field was comparable to or greater than initial excess electron energy, photoluminescence quenching was observed. Quenching in cadmium telluride (CdTe) and gallium arsenide (GaAs) is linearly proportional to the intensity of incident terahertz waves and reaches up to 17% and 4%, respectively, at a peak terahertz intensity of 13 MW/cm2. The photoluminescence measurement reveals that the ultrafast decay times of terahertz-pulse-induced quenching are 700±60 fs for CdTe and 350±30 fs for GaAs.
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78.55.Et II-VI semiconductors
78.55.Cr III-V semiconductors
78.47.jd Time resolved luminescence
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Emission characteristics of GaN-based blue lasers including a lattice matched Al0.83In0.17N optical blocking layer for improved optical beam quality

A. Castiglia, J.-F. Carlin, E. Feltin, G. Cosendey, J. Dorsaz, and N. Grandjean

Appl. Phys. Lett. 97, 111104 (2010); http://dx.doi.org/10.1063/1.3489108 (3 pages) | Cited 5 times

Online Publication Date: 13 September 2010

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We demonstrate room-temperature continuous-wave operation of 425 nm InGaN-based blue laser diodes including a thin Al0.83In0.17N optical blocking layer. Structures are grown on c-plane GaN freestanding substrates with a lattice-matched AlInN layer positioned below an Al0.07Ga0.93N bottom cladding. Such devices are compared to standard InGaN based lasers looking at threshold current density, electrical characteristics, and far-field emission. Threshold current densities of 4 kA/cm2 and slope efficiencies of ∼ 0.6 W/A (for uncoated facets) have been achieved in AlInN containing devices. Lower mode leakage in the substrate is highlighted by a better transversal far-field pattern resulting in an improved beam quality.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.81.Bm Fabrication, cladding, and splicing
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers

Jing Zhang, Hongping Zhao, and Nelson Tansu

Appl. Phys. Lett. 97, 111105 (2010); http://dx.doi.org/10.1063/1.3488825 (3 pages) | Cited 30 times

Online Publication Date: 14 September 2010

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The optical gain characteristics of high Al-content AlGaN quantum wells (QWs) are analyzed for deep UV lasers. The effect of crystal-field split-off hole (CH) and heavy-hole (HH) bands crossover on the gain characteristics of AlGaN QW with AlN barriers is analyzed. Attributing to the strong transition between conduction–CH bands, the TM spontaneous emission recombination rate is enhanced significantly for high Al-content AlGaN QWs. Large TM-polarized material gain is shown as achievable for high Al-content AlGaN QWs, which indicates the feasibility of TM lasing for lasers emitting at ∼ 220–230 nm.
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42.55.Px Semiconductor lasers; laser diodes

Superconducting plasmonics and extraordinary transmission

A. Tsiatmas, A. R. Buckingham, V. A. Fedotov, S. Wang, Y. Chen, P. A. J. de Groot, and N. I. Zheludev

Appl. Phys. Lett. 97, 111106 (2010); http://dx.doi.org/10.1063/1.3489091 (3 pages) | Cited 9 times

Online Publication Date: 14 September 2010

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Negative dielectric constant and dominant kinetic resistance make superconductors intriguing plasmonic media. Here we report on the first study of one of the most important and disputed manifestations of plasmonics, the effect of extraordinary transmission through an array of subwavelength holes, using a perforated film of high-temperature superconductor. We show that in the millimetric wave part of the spectrum exceptionally strong extraordinary transmission exists in the ideal conductor state, improves in the plasmonic regime of a superconductor, and diminishes in a highly lossy metal.
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77.22.Ch Permittivity (dielectric function)
73.22.Lp Collective excitations

Photoconductance of a submicron oxidized line in surface conductive single crystalline diamond

M. Stallhofer, M. Seifert, M. V. Hauf, G. Abstreiter, M. Stutzmann, J. A. Garrido, and A. W. Holleitner

Appl. Phys. Lett. 97, 111107 (2010); http://dx.doi.org/10.1063/1.3487785 (3 pages) | Cited 5 times

Online Publication Date: 14 September 2010

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We report on sub-bandgap optoelectronic phenomena of hydrogen-terminated diamond patterned with a submicron oxidized line. The line acts as an energy barrier for the two-dimensional hole gas located below the hydrogenated diamond surface. A photoconductive gain of the hole conductivity across the barrier is measured for sub-bandgap illumination. The findings are consistent with photogenerated electrons being trapped in defect levels within the barrier. We discuss the spatial and energetic characteristics of the optoelectronic phenomena, as well as possible photocurrent effects.
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78.56.-a Photoconduction and photovoltaic effects
71.55.Ht Other nonmetals
81.05.ug Diamond
73.25.+i Surface conductivity and carrier phenomena
72.40.+w Photoconduction and photovoltaic effects

Toward remote high energy terahertz generation

Tie-Jun Wang, Shuai Yuan, Yanping Chen, Jean-François Daigle, Claude Marceau, Francis Théberge, Marc Châteauneuf, Jacques Dubois, and See Leang Chin

Appl. Phys. Lett. 97, 111108 (2010); http://dx.doi.org/10.1063/1.3490702 (3 pages) | Cited 6 times

Online Publication Date: 15 September 2010

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Remote terahertz (THz) generation from a two-color femtosecond laser-induced filament in air was experimentally demonstrated. A record of remote THz emission at 16 m was achieved. THz pulse energy more than 250 nJ in the frequency range below 5.5 THz was recorded; this is two orders of magnitude stronger than that from single-color excitation. Back-scattered nitrogen (N2) fluorescence signal remotely measured with a lidar is linearly proportional to the THz emission, which would provide a more practical method to characterize the THz pulses.
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84.40.-x Radiowave and microwave (including millimeter wave) technology
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Effects of (NH4)2S and NH4OH surface treatments prior to SiO2 capping and thermal annealing on 1.3 μm GaInAsN/GaAs quantum well structures

V. Polojärvi, J. Salmi, A. Schramm, A. Tukiainen, M. Guina, J. Pakarinen, E. Arola, J. Lång, I. J. Väyrynen, and P. Laukkanen

Appl. Phys. Lett. 97, 111109 (2010); http://dx.doi.org/10.1063/1.3487784 (3 pages) | Cited 3 times

Online Publication Date: 15 September 2010

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We report the influence of (NH4)2S and NH4OH surface treatments prior to SiO2 capping and subsequent rapid thermal annealing, on optical properties of GaInAsN/GaAs quantum-well (QW) structures. We observed an increase in QW photoluminescence (PL) emission for the (NH4)2S treated samples as compared to the untreated sample. After annealing, also the NH4OH treated sample showed significant improvement in PL. The treatments were also found to decrease the In out-diffusion and reduce the blueshift upon annealing. The PL results are discussed with x-ray diffraction and x-ray photoemission data from SiO2/GaAs, in particular, with changes found in Ga 3d spectra.
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78.67.De Quantum wells
81.65.-b Surface treatments
61.72.Cc Kinetics of defect formation and annealing
66.30.H- Self-diffusion and ionic conduction in nonmetals
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors

Longitudinal optical phonon assisted polariton laser

M. Maragkou, A. J. D. Grundy, T. Ostatnický, and P. G. Lagoudakis

Appl. Phys. Lett. 97, 111110 (2010); http://dx.doi.org/10.1063/1.3488012 (3 pages) | Cited 5 times

Online Publication Date: 16 September 2010

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We demonstrate the role of longitudinal optical (LO)-phonon assisted polariton relaxation in reducing the stimulation threshold in strongly coupled microcavities. When the energy of the relaxation bottleneck is one LO-phonon above the ground polariton state, we observe a tenfold improvement of the polariton relaxation rate in the linear regime, and a twofold reduction in the threshold to the nonlinear polariton lasing regime.
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42.55.Sa Microcavity and microdisk lasers
42.55.Px Semiconductor lasers; laser diodes
42.65.-k Nonlinear optics

Emission mechanisms of passivated single n-ZnO:In/i-ZnO/p-GaN-heterostructured nanorod light-emitting diodes

Hsin-Ying Lee, Ching-Ting Lee, and Jheng-Tai Yan

Appl. Phys. Lett. 97, 111111 (2010); http://dx.doi.org/10.1063/1.3490652 (3 pages) | Cited 6 times

Online Publication Date: 16 September 2010

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The single n-ZnO:In/i-ZnO/p-GaN-heterostructured n-i-p nanorod was deposited using a vapor cooling condensation system. The photoelectrochemical system was used to directly passivate the nanorod sidewall surface with a Zn(OH)2 layer. The electrical performance of the passivated and unpassivated single nanorod was measured using a conductive atomic force microscopy. The resulting nanorod light-emitting diodes were investigated for understanding the relevant light emission mechanisms. Since the nonradiative recombination centers, native defects, and dangling bonds existed on the nanorod sidewall surface were effectively passivated, the resultant surface leakage current was reduced and the near-band emission intensity of the nanorod light-emitting diode was increased accordingly.
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85.60.Jb Light-emitting devices

Optical phase detection in a 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate crystal for terahertz time domain spectroscopy system at 1.55 μm wavelength

M. Martin, J. Mangeney, P. Crozat, and P. Mounaix

Appl. Phys. Lett. 97, 111112 (2010); http://dx.doi.org/10.1063/1.3490706 (3 pages) | Cited 3 times

Online Publication Date: 16 September 2010

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We report the electro-optic detection of terahertz (THz) pulses in a 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate crystal (DAST) using optical phase detection technique and femtosecond optical pulses at telecom wavelength. A THz time-domain spectroscopy system based on 1.55 μm wavelength fiber laser pulses that integrates an ion-irradiated In0.53Ga0.47As photoconductive antenna as the emitter and a DAST electro-optic crystal as the detector is shown to provide a detection bandwidth of 5 THz.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
42.79.-e Optical elements, devices, and systems
84.40.-x Radiowave and microwave (including millimeter wave) technology

λ ∼ 3.36 μm room temperature InGaAs/AlAs(Sb) quantum cascade lasers with third order distributed feedback grating

J. P. Commin, K. Kennedy, D. G. Revin, S. Y. Zhang, A. B. Krysa, and J. W. Cockburn

Appl. Phys. Lett. 97, 111113 (2010); http://dx.doi.org/10.1063/1.3487781 (3 pages) | Cited 1 time

Online Publication Date: 16 September 2010

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We report on the development of strain compensated InGaAs/AlAs(Sb) quantum cascade lasers, incorporating a buried third order distributed feedback grating. Single mode operation with a side mode suppression ratio of ∼ 30 dB has been achieved in the wavelength range of 3.358–3.380 μm for temperatures between 270 and 360 K. The threefold increase in grating pitch size, compared with a first order grating, allows conventional photolithographic techniques to be used for single mode laser fabrication.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.79.Dj Gratings
42.82.Cr Fabrication techniques; lithography, pattern transfer

320 fs pulse generation from an ultrafast laser inscribed waveguide laser mode-locked by a nanotube saturable absorber

S. J. Beecher, R. R. Thomson, N. D. Psaila, Z. Sun, T. Hasan, A. G. Rozhin, A. C. Ferrari, and A. K. Kar

Appl. Phys. Lett. 97, 111114 (2010); http://dx.doi.org/10.1063/1.3486177 (3 pages) | Cited 15 times

Online Publication Date: 17 September 2010

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Ultrafast laser inscription is used to fabricate the gain element for a mode-locked Er-doped bismuthate glass waveguide laser. Mode-locking is initiated and stabilized by the use of a single wall carbon nanotube saturable absorber. The waveguide laser produces 320 fs pulses at 1.56 μm with a pulse repetition rate of 40 MHz and average output power of 1.25 mW.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.60.Fc Modulation, tuning, and mode locking
42.82.Cr Fabrication techniques; lithography, pattern transfer

Enhanced color conversion from colloidal CdSe/CdS dot/rods by vertical microcavities

H. Pühringer, J. Roither, M. V. Kovalenko, M. Eibelhuber, T. Schwarzl, D. V. Talapin, and W. Heiss

Appl. Phys. Lett. 97, 111115 (2010); http://dx.doi.org/10.1063/1.3491065 (3 pages)

Online Publication Date: 17 September 2010

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Colloidal CdSe/CdS dot/rods exhibit efficient photoluminescence from the spherical CdSe dots at wavelengths well below the absorption edge of the rod material. This property makes dot/rods advantageous for color conversion applications, especially when they are embedded in optical microcavities to improve light extraction in forward direction. Here, surface emitting half-wavelength microcavities are demonstrated containing films of dot/rods as active material, exhibiting luminescence enhancement factors of up to 21 at the resonator wavelengths, whereas with conventional CdSe/ZnS core-shell nanocrystals only half of this value is obtained.
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78.67.Qa Nanorods
78.55.Et II-VI semiconductors
81.05.Dz II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
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Negative, positive, and infinite mass properties of a rotating electron beam

David M. French, Brad W. Hoff, Y. Y. Lau, and R. M. Gilgenbach

Appl. Phys. Lett. 97, 111501 (2010); http://dx.doi.org/10.1063/1.3488833 (3 pages) | Cited 2 times

Online Publication Date: 14 September 2010

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An electron rotating under a uniform axial magnetic field and a radial electric field exhibits an effective mass that may be negative, positive, or infinite, in response to an azimuthal electric field. This paper reports simulation results that show instability and stability when the effective mass are negative and positive, respectively, depending on the magnitude and orientation of the radial electric field. Thus, the inverted magnetron would have a much faster startup than the conventional magnetron, an important consideration for pulsed operation. When the effective mass is infinite, the electrons hardly respond to an azimuthal ac electric field.
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41.75.Fr Electron and positron beams
75.85.+t Magnetoelectric effects, multiferroics
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)

Comparative and quantitative study of neutral debris emanated from tin plasmas produced by neodymium-doped yttrium-aluminum-garnet and carbon dioxide laser pulses

Yuji Matsuoka, Yuki Nakai, Shinsuke Fujioka, Shinsuke Maeda, Masashi Shimomura, Yoshinori Shimada, Atsushi Sunahara, Hiroaki Nishimura, and Minoru Yoshida

Appl. Phys. Lett. 97, 111502 (2010); http://dx.doi.org/10.1063/1.3486170 (3 pages) | Cited 1 time

Online Publication Date: 15 September 2010

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Amount of neutral debris emanated from extreme ultraviolet light source must be minimized to maximize its lifetime. Emanation of neutral atomic debris was experimentally investigated using laser-induced-fluorescence technique for carbon dioxide (CO2, 10.6 μm in wavelength) and Nd-doped yttrium-aluminum-garnet (Nd:YAG, 1.064 μm) lasers irradiated tin foils. Total number of neutral atomic debris from CO2 laser-irradiated tin foils was 1/100 times smaller than that from Nd:YAG irradiated ones. Competitiveness of CO2 laser was revealed in terms of debris mitigation.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.50.Dg Plasma sources
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Tx Emission, absorption, and scattering of particles
42.72.Bj Visible and ultraviolet sources

Rare-earth plasma extreme ultraviolet sources at 6.5–6.7 nm

Takamitsu Otsuka, Deirdre Kilbane, John White, Takeshi Higashiguchi, Noboru Yugami, Toyohiko Yatagai, Weihua Jiang, Akira Endo, Padraig Dunne, and Gerry O’Sullivan

Appl. Phys. Lett. 97, 111503 (2010); http://dx.doi.org/10.1063/1.3490704 (3 pages) | Cited 18 times

Online Publication Date: 15 September 2010

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We have demonstrated a laser-produced plasma extreme ultraviolet source operating in the 6.5–6.7 nm region based on rare-earth targets of Gd and Tb coupled with a Mo/B4C multilayer mirror. Multiply charged ions produce strong resonance emission lines, which combine to yield an intense unresolved transition array. The spectra of these resonant lines around 6.7 nm (in-band: 6.7 nm ±1%) suggest that the in-band emission increases with increased plasma volume by suppressing the plasma hydrodynamic expansion loss at an electron temperature of about 50 eV, resulting in maximized emission.
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52.50.Dg Plasma sources
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
42.72.Bj Visible and ultraviolet sources
42.79.Bh Lenses, prisms and mirrors
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
42.79.Wc Optical coatings
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Single crystal-like selection rules for unipolar-axis oriented tetragonal Pb(Zr,Ti)O3 thick epitaxial films

Mitsumasa Nakajima, Takashi Fujisawa, Yoshitaka Ehara, Tomoaki Yamada, Hiroshi Funakubo, Hiroshi Naganuma, Soichiro Okamura, Ken Nishida, Takashi Yamamoto, and Minoru Osada

Appl. Phys. Lett. 97, 111901 (2010); http://dx.doi.org/10.1063/1.3488015 (3 pages)

Online Publication Date: 13 September 2010

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We investigated the polarized Raman spectra of a strain-free, unipolar-axis oriented tetragonal Pb(Zr,Ti)O3 thick epitaxial film. We evaluated the single crystal-like selection rules of the A1- and E-symmetry components, and found an anomalous behavior in the angular dependence of the A1(1TO)-mode intensity similar to that observed in high-Tc superconductor single crystals. Raman tensor analyses of the A1(1TO) mode revealed complex phases may exist between two independent Raman-tensor components even in the single 180° domain state.
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78.30.Hv Other nonmetallic inorganics
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
77.55.Px Epitaxial and superlattice films

Dielectric functions and interband transitions of In1−xAlxSb alloys

J. J. Yoon, T. J. Kim, Y. W. Jung, D. E. Aspnes, Y. D. Kim, H. J. Kim, Y. C. Chang, S. H. Shin, and J. D. Song

Appl. Phys. Lett. 97, 111902 (2010); http://dx.doi.org/10.1063/1.3488827 (3 pages) | Cited 2 times

Online Publication Date: 13 September 2010

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Pseudodielectric functions 〈ε〉 of In1−xAlxSb ternary alloy films were determined from 1.5 to 6.0 eV by spectroscopic ellipsometry. Overlayer effects were minimized by performing in situ chemical etching to more accurately determine intrinsic bulk dielectric responses. Critical-point (CP) energies of structures were determined from numerically calculated second energy derivatives. Where necessary, Brillouin-zone origins were identified by electronic band structure calculations done with the linear augmented Slater-type orbital method. These calculations also showed increasing separation of the E2 and E2′ CP structures with increasing Al-composition
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71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
71.20.Gj Other metals and alloys

Nanoductility induced brittle fracture in shocked high performance ceramics

Paulo S. Branicio, Rajiv K. Kalia, Aiichiro Nakano, and Priya Vashishta

Appl. Phys. Lett. 97, 111903 (2010); http://dx.doi.org/10.1063/1.3478003 (3 pages) | Cited 4 times

Online Publication Date: 13 September 2010

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Nanoductility induced crack nucleation mechanism mediated by a single dislocation core is revealed in a 300 million-atom molecular dynamics simulation of shocked silicon carbide ceramic. The atomistic damage mechanism involves dynamic transitions between clearly delineated regimes—from shock-induced structural transformation to plastic deformation to brittle fracture. Such atomistic understanding may help in the design of nanocrack suppression strategies to realize predictive modeling of complex damage processes in high-performance ceramics.
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81.40.Lm Deformation, plasticity, and creep
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.mm Fracture
62.20.mt Cracks
62.20.fk Ductility, malleability
62.50.Ef Shock wave effects in solids and liquids

Subterahertz characterization of ethanol hydration layers by microfluidic system

S. Laurette, A. Treizebre, F. Affouard, and B. Bocquet

Appl. Phys. Lett. 97, 111904 (2010); http://dx.doi.org/10.1063/1.3488832 (3 pages) | Cited 6 times

Online Publication Date: 13 September 2010

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Characterizations of ethanol hydration layers are examined through subterahertz spectroscopy of water/ethanol mixtures by using a microfluidic system. A three-component model is used to explain measurements discrepancies with the Lambert–Beer law and to determine ethanol hydration shell absorption. Moreover, the hydration shell distribution is compared with molecular dynamics simulations with a good agreement. Ethanol hydration number is then computed and it can quickly characterize only the first water hydration layer or the whole hydration shell, depending on the chosen extraction model.
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47.85.Np Fluidics
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
71.15.Pd Molecular dynamics calculations (Car-Parrinello) and other numerical simulations

The TiAl channel mechanism for enhanced (de)hydrogenation kinetics in Mg-based films

Shiqiang Hao

Appl. Phys. Lett. 97, 111905 (2010); http://dx.doi.org/10.1063/1.3489672 (3 pages) | Cited 4 times

Online Publication Date: 13 September 2010

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The transport properties of hydrogen in metal additives are very important for understanding the enhanced kinetic processes of (de)hydrogenation in metal hydrides. Based on the first-principles calculations, we found that the H2 dissociation rates on TiAl surfaces are very facile and the dissociated H diffusion in TiAl lattice is much faster than that in host material MgH2. We propose that the “catalytic” effect of additives Ti and Al is the H transport channel within the Mg and MgH2 host materials for the enhanced reaction kinetics.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
68.43.Mn Adsorption kinetics
68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation
68.43.Bc Ab initio calculations of adsorbate structure and reactions
82.20.-w Chemical kinetics and dynamics

Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

I. Sarkar, M. Laux, J. Demokritova, A. Ruffing, S. Mathias, J. Wei, V. Solovyeva, M. Rudloff, S. S. Naghavi, C. Felser, M. Huth, and M. Aeschlimann

Appl. Phys. Lett. 97, 111906 (2010); http://dx.doi.org/10.1063/1.3489098 (3 pages) | Cited 3 times

Online Publication Date: 14 September 2010

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We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.A- Nucleation and growth
64.70.fm Thermodynamics studies of evaporation and condensation

Spectral analysis of resonance ultrasonic spectroscopy: Kramers–Kronig analysis, Fano profiles, and the case of precursor softening in SnTe:Cr

D. J. Safarik, E. K. H. Salje, and J. C. Lashley

Appl. Phys. Lett. 97, 111907 (2010); http://dx.doi.org/10.1063/1.3489376 (3 pages) | Cited 4 times

Online Publication Date: 14 September 2010

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The analysis of resonant ultrasound spectroscopy (RUS) spectra is exemplified by the study of elastic softening in single-crystal Sn0.995Cr0.005Te near the ferroelastic phase transition at T ≃ 100 K. Kramers–Kronig analysis of the resonance peaks shows that the elastic response is linear over the entire temperature range. In the paraelastic phase the Cole–Cole plots of the RUS spectra are circles with small gaps that are related to linear damping. In the ferroelastic phase strong coupling with domain boundary movement occurs, and results in distortion of the Cole–Cole circles. The RUS line profiles in the ferroelastic phase are well-described by the sum of a resonance term and a Fano spectrum with a Fano parameter of q = 0.46. The general equations and some simple approximations, which can conveniently be used to analyze RUS spectra, are summarized. We expect that this analysis is transportable to a large parameter space and can be applied to most RUS spectra for both ferroic and nonferroic materials.
Show PACS
78.20.-e Optical properties of bulk materials and thin films
72.25.-b Spin polarized transport
79.60.-i Photoemission and photoelectron spectra
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